Battery Handbook

Rathbone's Use & Care Of Batteries & Chargers: A very valuable guide for the buyer or user of rechargeable and primary battery packs in your organization. Also the later part is a detailed collection of discussions from true experts in the battery cell field regarding "Memory Effect".

This handbook is supported by manufacturers battery cell specification sheets. Reference information pulled from Anton Bauer, Cadex, Christie, Gates, GE, Saft, Sanyo, PAG, and Panasonic manuals or specification sheets, as well as our own in-depth knowledge and experience in the battery and analyzer industry.

The following information is applicable in any market that requires primary or rechargeable battery packs and chargers. We will use the main battery packs of one particular market for the illustration.

Battery Packs and Cells.
The use and care of these battery packs is also the same for rechargeable battery packs in any other market. In this market there are approximately five standard types of battery packs to choose from:
1. NP1 Series
2. BP-90 Series
3. Brick Series, ( Unsealed screw together & Sealed)

4. Battery Belts
5. Film Lunch Box Battery Packs

There are approximately four companies building good chargers. One is considered a high end “smart” charger and three manufacture Battery Management Analyzer Systems? All four of these systems are better and best type chargers.

There are approximately three companies that provide complete battery and charger systems manufactured by themselves.

There are dozens of street vendor battery assemblers manufacturing battery packs with varying if any quality.

Beware, some of these street vendors are very good providing quality at a profit but some are marketers providing product at a profit.

The buyer for your product will do better to go to a quality aftermarket company who supports their product with black and white manufacturers battery cell specification sheets and listed prices of the batteries and chargers for your system. You will receive better product and better price from a black and white vendor hard copy. Stay away from vendors with vague or generalized product descriptions and who do not list their prices for all to see. Always ask for specification sheets on the product you are considering. The exact specifications should also be on the purchase order, packing slip and invoice. If the vendor has specification sheets, you are on the correct road! If the vendor supplies you the sales pitch in writing you may still be on an acceptable road. Look closely at the written sales pitch and verify the authority of the writing person then pay attention to the purchase order, packing slip and invoice.

If the vendor does not understand why you need specification sheets in writing before giving them your purchase order or money, you have a company selling product for profit. There are a few of these street vendors that have been around a long time and some of those close, open, and close again under the same or a different name.

BEWARE..., customer education of the product is NOT in that vendors best interest.

Another consideration in your choice of battery cells is this:
Negative Delta V Charge:
( “Sales Pitch”)...., If you are using a Smart charger or a Battery Management System, you can use a press negative or brand name but low end "economical" cell or a high end sinter cell technology. Using a smart charger or Analyzer charger will allow you to use the less expensive cell with no harm to that cell pack from the more sophisticated charger.

This is true..., But, the charge rate can damage a battery cell if the battery cell is not designed to accept the heat generated by faster rate of charge or from a trickle (overnight) charger. The smart chargers and our Analyzer charger units use a negative delta V charging technique and cut off the fast charge at the voltage peak so the press negative cell is not damaged.

Trickle (Overnight) Charge:
Some manufacturers’ chargers go to, or use, a “trickle” charge technique giving a constant very low charge and teach this as “not harmful” to your battery pack.

THIS IS NOT TRUE!!! Continually heating the insulator between the positive and negative plates of any battery cell will cook the insulator. The insulator becomes brittle, breaks apart and allows the negative and positive plates to touch, allowing the battery cell to short.

Consider:
A crock pot placed on its lowest setting. You place a fresh roast in the crock pot and leave it there all day. You can go by the pot and touch the pot anytime through the day. It will be warm but will not burn you.

Yet that evening the fresh juicy red roast is no longer red but dark and a finished cooked product. That is what a trickle charge does to the insulator between the negative and positive plates of the high quality or low quality battery cell in your battery pack.

Heat Damage:
Also, most people we are exposed to as a user or dealer focus on the charge system used on the battery pack and make allowance for lower end cells (with a sophisticated charging system), but forget to consider the DISCHARGE rate of the battery pack. The number one enemy of your battery cell is heat! A heavy or long term discharge

rate on a battery pack is much more destructive to the cells than an unsophisticated charger and certainly a sophisticated charger. Cell quality is important! “You do get what you pay for.” The press negative cell has more internal resistance than the sinter cell technology.

Patching...,Fixing.... A NO, NO, NO!
Another trick we see is “patching” or "Fixing" battery packs. When a battery pack is somewhat new and still under warranty, it is acceptable to change a cell in an assembly environment using a welder, not a solder gun. A welder does not harm the cell but a solder gun placed to the cell will burn the insulator between the two plates. A welder will not cause a voltage drop but a solder joint will always cause a voltage drop. Several voltage drops will damage the performance of the battery pack and create problems for a sophisticated charger system. The charger system cannot get an accurate reading of the battery pack due to false readings because of the voltage drops.

Over time, another problem with patching is that you have several different cells in series or parallel as the case may be, each with a different capacity reading and strength. The newest cell placed in the pack becomes the lead and attempts to do the work of every cell that is not up to the same standards. This will cause the new cell to wear down rapidly to the performance levels of the other cells in that pack. It is like placing a new dog at the front of a team of dogs who have been run all day and telling that new dog to take that old team and run all night. The new dog wears himself out trying to pull the tired dogs along with him. Your battery pack is only as strong as the weakest cell!

In today’s economy television stations, professional film and video companies, freelance people and anyone else in the industry responsible to maintain and replace the rapidly changing technology have many things they must consider. Many of these are of no importance to the salesperson trying to supply the package they represent. In the tough competitive market today, many salespeople look for areas to remove cost and become the favored low bid with all the bells and whistles. (Of course, that salesperson is not concerned with your long range forecast except to offer a replacement somewhere in the future and only then to supply you with a specific battery for that new system.)

However, the more appropriate choice for you would be to select a battery system that can be rebuilt and continue to grow with your change in equipment technology. This will greatly reduce your accessory purchases and expense budget. Smart buying in a long range plan involves:

Purchasing a flexible battery pack that will work with your existing system and future system needs.
Purchasing a charger system that will work for multiple battery packs, and,
Beware of cheap, “Analyizer \ Conditioners”, that
Burn your battery pack and Waste your Charge Discharge Cycles. Many times the salesperson may suggest that you reduce your expense so they can be the low bid and this will most likely be in the battery and charger package.

A smart buyer (and a smart, well intended, salesperson) should ask the following questions:

Will you ever change systems again and can you use this same battery and charger system on more than one style of camera?
Will you be suing more than one manufacturers battery packs or chargers?
Will you ever change the way you run the business again, i.e., more news, or more outside production etc? This could mean more or different camera systems. You want to keep your expense at a minimum with a consistent and flexible battery and charger system that will work on current systems as well as any other systems you purchase in the future. Your decision regarding battery packs and chargers is important!

Different battery packs require different styles of chargers. Universal style battery packs can utilize the same charger system. A system like the, CADEX 7000, Christie CASP 2500, or PAG ACS. Saving you $$$ that can be invested elsewhere, like more battery packs from Rathbone Energy , Inc.

As an example, the BP- 90 is a better alternative than the NP1 Series for versatility of Sony Product.

In a large environment you may need the versatility of all five of the major battery types. Because of this, chargers used in-house, Like the CADEX 7000, Christie CASP, or PAG ACS can be purchased with the versatility of managing all the different types of battery packs while the user in the field will have a less expensive but versatile unit for their battery. However, the potential for completely changing systems or adding an additional system down the road suggest reason for more flexible choices or smart purchasing.

A good example of adding flexibility to your TV news needs with minimal expense:

Use an Anton Bauer or PAG manufactured adapter plate and have your choice of vendor provide bricks for these systems. Then, no matter what you do, all you need for versatility is a new adapter plate for an additional system and you continue to use your existing brick style battery.

Whether it is a screw together battery unit or a sealed battery unit you may significantly reduce your future replacement expenses by purchasing inserts from Rathbone Energy , Inc. and rebuilding the units in-house or by allowing Rathbone Energy , Inc. to rebuild the unsealed or sealed battery pack for you. We can also assist your technician by telephone in the opening of a sealed unit as we supply you the inserts for those sealed units. Other points of interest:

You also reduce the need for different types of chargers unless you are adding equipment for a new crew.
Consider if the battery does or does not have temperature protection and or voltage/current protection fuses internally (depending on the battery).
Some NP1 Series batteries have no thermal protection exposing your systems to potential damage.
BP-90 and Brick Style Batteries can come in several qualities.
Brand Name is not all to consider as every brand name has high end cells and low end cells.
- Besides the choices of high end and low end series models you have the “Gray” area.
  - When a cell manufacturer runs a cell line in the factory, only a small percentage of those cells come out meeting ALL of the specification sheet requirements. They are the most expensive of that lot. The rest are graded on their percentage of capacity and sold accordingly. This is why the manufacturers have additional codes along with a date code and line manufacturing code. They also have the capacity code. Thus, you may have three vendors offering the same brand, model, size, and amperage cell but with dramatically different price structures.
  - You also have the very important choice of the lower end cell commonly referred to as press negative cells and the high end best quality cell. The press negative or sintered on sinter reference is the type of manufacturing process used to produce the particular cell.
  - Other considerations include Volts, Amperage, Wattage, Cycles, and Warranty. The “C” Rate on their label presents or qualifies the amperage claimed.

Chargers:
We sell all high end Battery Management Analyzer Chargers: CADEX, PAG ACS and Rathbone Energy.

We still design and can manufacture chargers similar to our retired Analyzer+300 & Analyzer+500 Systems.

Analyzer:
After charger is plugged in, turned on and system has run diagnostic codes and all lights are off, then place

NP1 Batteries on the unit.

Chargers:
We can custom design, sell boards, and sell a license on our products and software as well as private label.

Christie, CADEX, PAG, Rathbone Energy are the only sophisticated charging systems that qualify as a battery management analyzer charging system.

Several companies do produce “smart chargers” for particular markets in mass volume, like for cellular phones or communications radios. These are individual units, again produced in Very Mass Volume for that particular market.

The others we know off develop similar multi-port systems for One Specific Market, TV News.

“Smart Chargers” can be simple software to semi complex software. Almost all are simple smart software.

There are three basic types of charging systems for Ni-CD cells or battery packs.

1. Time charge method
2. Temperature charge method
3. Negative delta V cut off methods.

4. Add dT/dT for Nickel Metal Hydride

5. Add Constant Current / Constant Voltage for Lithium Ion

Time is strictly a timing mechanism that is set to charge at a particular rate for a set time and then either turn completely off or reduce the charge rate to a lower charge rate for a set or indefinite time.

Temperature Method is a design that requires a temperature sensor in series built into the battery pack itself. The temperature charger method looks for this temperature sensor to open.

This “open” in the current path tells the temperature charger to either reduce or turn off the charge current to the battery pack. These can be very simple to more complex designs with detail for levels of reduction in current path by placing several temperature sensors in the pack with different calibrations producing different results in the current flow.

If the battery is below a certain temperature do not charge. If the battery is between A & E charge at this rate, if another sensor tells you the battery is between D+ & J charge at this rate and so on.
Negative Delta V is the beginning of a simple smart

system. Negative Delta V is programmed to look for a particular voltage peak in the battery cell or battery pack. It is much more accurate than the other two methods.

Most Negative Delta V systems look for a voltage peak at approximately .2V to .3 V above the voltage peak and tell the charger the next instructions. For example, to turn off or to go to a reduced charge current or something of that nature.

A sophisticated charger system will incorporate all of these three methods in their charger routine as safety backup to the first charge routine.

This would be to use the negative delta V charge method for initial charge routine and for a safety on the battery and charger to protect the battery, the charger and the product you would back up the negative delta V charge routine with the temperature sensor to detect too much dissipating heat or to detect a battery that is too cold and prevent the charge routine until the battery has reached a safe temperature environment.

Third would be the back up of the timing routine at one and one half times the needed charge time for the said battery pack. Thus if the negative delta V fails and the temperature sensor fails the system will still turn off when the battery as charged for one and one half the time

charge routine.

With a combination of these routines you develop a simple to semi-complex charger routine.

The more complex methods use the above mentioned routines in combination with algorithms and other criteria to develop a battery management system. We will not go into any heavier detail at this point as not to expose our patients or trade secrets.

These type systems require very sophisticated chips and a strong EE with a strong software background, strong background and understanding of the battery chemical and battery cell itself.

“Analyzer \ Conditioner”

This term usually goes with a simple charger system that has some type of fuel gauge to analyze an approximate capacity of the cell or battery pack. The condition routine is a very simple routine to “deep” discharge the battery pack to 1.0V per cell one or more times to reduce what was once called the “memory effect”. They are very simple and almost always a waste of money. Beware of any system that will discharge a cell below .7 volts (per engineering specs. you can damage the cell).

Battery Memory (Discussions by experts are in the last 20% of this article)

Memory is only approximately 10% of the demon it was 10 years ago.

The definition of memory is simple. The battery cell has an electrolyte chemical between the positive and negative cells placed on a gauge or insulator.

The moving of this electrolyte from one side to the other is the chemical reaction that generates the energy or current from the battery cell or battery pack.

When a battery pack is not thoroughly used in the field every time it will, over time, develop a chemical change called a crystallization build up on the insulator.

When the electrolyte changes in chemical form to this crystallization, it will not

move through the insulator gauge and will not create the desired chemical reaction. Thus, you will not have the same intensity of energy generation.

This problem developed several “witch” remedies such as to deep discharge the battery with a lamp or allow the system to run until the product will not operate anymore, not even to power any LED. These remedies create several damaging effects to the battery cell or pack and “memory” would always be blamed for these problems. As the smoke screen of memory is removed we find that these techniques to remove “memory” were actually doing more damage to the cells and battery packs than anything else including analyzer conditioners. Trickle (overnight) chargers increase this problem.

Anyone, one person or company telling you that there is such a thing as memory is simply promoting low end cells or does not know batteries. Either way, they should not be in the battery business.

When the battery pack or cell is discharged below 1.0V per cell ( per engineering specification manuals) you create the opportunity for reverse discharge cells and or extremely unbalanced cells.
We discussed these effects and the correct procedures previously using the analogy of the team of dogs.

A new battery may be safely used with no unwarranted abuse or misuse of the battery pack if the following options are used.

1. The product manufacturer should have a voltage cutoff method at 1.0V per cell designed into there product, and the product should shut completely down at this point. Meaning, when the battery reaches 1.0V per cell the system shuts completely down. The unit should also have a “approaching” voltage shut down warning at about 2 to 3 minute before actual shut down. Or say, an (audible and or visual) voltage cut off warning at 1.02 V per cell and a voltage shut down at 1.0 or .9 V per cell.
Some companies design product with a voltage shut down system, but the product itself will continue to draw power from the battery pack. If the user does not “turn off” the unit or “pull” the battery pack, the unit will continue to draw power from the battery even down to 0.0V per cell. This is the greatest cause of reversed discharge or extremely unbalanced battery cells or battery packs. If this is done on a regular basis the user will definitely damage the battery cell or pack very early in the battery charge discharge cycle life.

2. If the manufacture has not added these design features to save the consumer frustration and money:
Use the battery pack until the system does not operate properly and then place the back up battery in the unit, and recharge the first unit creating a battery rotation.

The charge time of the charging battery depends on what type of charger is used and the discharged level of the battery pack. If the charger has a cut off at full charge then you have no immediate worry. If the charger just continually charges with no cut of point you need to check the manual and see how long it takes to fully charge a discharged battery.

Purchase an electronic electrical wall timer and set that timer for 2 hours more than the manual specifications ( rule of thumb). This connects with the other sections that reference the analogy of the crock pot.

3. If the manufactured product comes with a sophisticated charger system such a one from Rathbone Energy, that we design, develop and can produce, the customer only uses his battery and places it on our system. We usually develop systems with a standard charge routing and a battery management system routine. The customer places his or her battery pack on a six week maintenance schedule. With a proper system such as what we design and develop, the customer only needs to run the Analyzer routine every 6th week.

We feel that they will keep their battery as clean as is possible with the least amount of maintenance using our battery management chargers and this procedure.

If you use a system that fully discharges the battery cell or pack to 1.0V per cell every single time you use the product you still greatly reduce the battery life expectancy by abusing the charge discharge cycle life of the battery pack.

Suppose you use the unit and only use 10% of the run time capacity and then discharge the battery pack. You wasted 90% of that one cycle. Most battery packs used in the medical industry are designed for 500 to 700 charge discharge cycles. It will not take a long time to process that battery pack through its anticipated charge discharge cycle life if this type processing

is done. Also, to keep the battery pack on a continual charge charger will cook the insulator, make the insulator brittle, breaking up and allowing the positive and negative plates to touch creating a shorted cell and battery pack.

It is our opinion that Ni-CD batteries can be safely stored for “up to” 2 years in a cool environment in a discharged state. We do not use battery cells on our shelves more than a few months old for our own manufacturing purposes. After that you can begin to see reductions in actual performance verses specification sheet performance.

Wet / Gel cell or dry cell lead acid cells can safely be stored off of the floor in a cool ,environment. These cells must be stored fully charged and they must be checked and recharged between every 30 to 60 day period.

Several companies manufacture battery assemblies, a few companies manufacture simple battery charger units and 3 (I can think of) manufacture a system they refer to as an analyzer \ conditioner. Two of those companies were in a long term legal battle over the charger system and it is not an accurate system even for an analyzer conditioner. It appears to work fine in the fast food industry, if you consider burning up the insulator fine.

Besides ourselves, we are aware of three companies that develop battery and battery charger systems for one particular market ( video) and that is their only market. Their systems are sophisticated smart chargers and battery packs for that particular industry.

Ourselves, Cadex, Christie and PAG are the only companies we are aware of that develop battery management analyzer systems and we sell all these chargers.

Engineering specification sheets call for a battery cell not to be discharged below 1.0 Volts per cell, otherwise they could damage the cell as discussed above. When we design a system charger we add another safety feature to warn the person responsible for battery packs of a video shooter, or person in their service discharging their packs below a particular voltage. This safety is incorporated in the following manner.

Engineering specification sheets list a fully charged battery pack at 1.25V per cell. In general purpose layman’s terms we reference as 1.2V per cell and yes, all Ni-CD battery cells are at 1.2V per cell fully charged.

All “ smart” systems have some type of chip inside the unit. Some use a very simple and basic chip, some use very sophisticated chips. Cadex, Christie, PAG and ourselves use a co-processor along with a very extensive line of highly sophisticated chips. These chips can be programmed with very simple routines to very complex routines. The cost of the chip is the same in a “non-expensive” and an “ expensive unit. The expense is in writing the detailed software routines so the company or user has all or non of the available “ bells and whistles”.

High End refers to a high quality battery cell . Also press negative cells have more internal resistance than sintered on sinter or pasted.

Any battery cell manufacture would be glad to mail you a product manual, but these do not tell you what I just have and they will not take the time to do this for individuals.

As for cell assembler’s, most do not intend to educate the user, or the customer in any way. The job is to sell what they have and education could cost them a sale.

Remember: (Short recap then on to the rest of the article)
Point of information:
All rechargeable battery packs have an “internal resistance”. This causes the battery pack or cell to discharge while on the shelf. A nickel cadmium battery cell or pack will loose 3% of its total charged capacity per day while sitting on the shelf.

“As a Rule of Thumb” A Alkaline battery cell can re-energize, but is not rechargeable.

If a rechargeable battery pack is continually discharged to zero it will be ruined and even if occasionally discharged to zero will stand a high probability of un-repairable damage.

If a Ni-CD battery is consistently discharged to a rate less than 1.0V per cell you can create unbalanced cells in the battery pack or if discharged very low, reverse discharge situation. With unbalanced cells, the battery pack will only charge to the weaker of all the cells in that pack. Our Battery Management Analyzer Chargers are designed to correct this problem if it is not too severe.

From our point of view, the length of time between use and discharge of a Ni-CD and recharge is not relevant. The Ni-CD pack can be stored for up to 2 years in a discharged state. If a Ni-CD is stored for a long period of time it will build back a percentage of its “ stamina” with proper charge, use, and discharge.

Reverse discharge means that the cells current is attempting to move in the correct negative to positive polarity and a number of the cells are attempting to move in the incorrect positive to negative polarity.

Memory effect is only 10% of the problem it was 10 years ago and can be kept at a minimum with proper maintenance of the battery pack as listed if articles already faxed or e-mailed to you.

Memory effect is the chemical reaction of the insulator between the negative and positive plates changing from a liquid or gel consistency to a crystallization build up thus not allowing the chemical reaction between the plates that will generate energy. The more crystal build up the less chemical reaction and the less the energy output. This would be accurate and not allow for misleading thoughts or understanding. Some assemblers and manufacturers would have a field day on my company with our shared customer market if I were quoted that way on “ Memory Effect”.

Trickle (overnight) chargers increase this problem.

Anyone one person or company telling you that there is such a thing as memory is simply promoting low end cells or does not know batteries. Either way, they should not be in the battery business.

Nickel Metal Hydride:

Nickel Metal Hydride cells are Great for cordless and cellular telephones as well as very small portable devices. They have made there way into the broadcast market and we will sell them.

It is my opinion, generally speaking, that nickel metal hydride cells will give you

50% more run time per density
50% less charge discharge cycles for the amperage cell
Cost 50% more per density
Cost 50% more for the charge discharge cycles given and cell amp hours
Do not hold up well under constant high current demand situations or heavy use.
For Broadcast: Also have less weight and do not assist in the balance of your camera lens / battery to your shoulder.

As for broadcast or heavy use devices you should simply compare the comparable manufacturers nickel metal hydride and nickel cadmium cell specifications sheets as well as your cost.

Conversion to Nickel Metal Hydride from Nickel Cadmium:

Some companies encourage you to convert your nickel cadmium battery pack to nickel metal hydride. We will do this conversion IF you are using a Cadex, PAG, or Rathbone Energy analyzer:

Nickel cadmium: To get the best performance from your nickel cadmium cells they should be charged with a primary charge routine of Negative Delta V backed up by voltage and then time cut-offs.
Nickel Metal Hydride: To get the best performance from your nickel metal hydride cells they should be charged using charge technique of DT/dt.
It is possible to charge a nickel metal hydride cell on a nickel cadmium charger that is designed to use a negative delta V charge circuit. BUT, you will NOT get the proper performance from your nickel metal hydride cells.
The consideration for the different circuitry in the battery packs themselves.

The Negatives of Lithium Ion Batteries

Great contacts for information on Lead Acid:
Dennis Sharpe of MK Battery is a very good authority on wheel chair batteries and they are a very good company.

Jack Verdin of Schauer Electronics is also a very good authority on wheelchair batteries and chargers. He is a remarkably bright person and always ready to share his knowledge.

I will note that wet cell and dry cell lead acid is different from Ni-CD in that when a product is being driven by a Ni-CD or Ni-MH product that the discharge rate is consistent from a fully charged to almost discharged state. Lead acid characteristics are different on this point as the discharge current of lead acid is more heavily produced from full charge and the discharge current reduces as the lead acid battery becomes more discharged. That is why it is very important to have a voltage regulation system on a product driven by a lead acid type battery.

Always discharge batteries to a voltage cut off between .8V & 1.0V per cell.

High discharge rates create more heat than a bad charger. Once we get past the old problem of MEMORY, we find that today’s battery problems are not memory so much as they are unbalanced cells, reverse discharge cells within the battery pack, and the use of trickle (overnight) chargers.

Heat deteriorates the insulator between the plates of metal inside the cell, thus creating the shorted cell.

This is why press negative cells,( 500 - 700 charge - discharge cycles ) do not hold up as well as sinter on sinter cells / paste cell ( 900 - 1200 charge - discharge cycles ) do in heavy or long duration discharge situations.

Never mix different capacity cells. It is better on your battery NOT to mix new and older cells because you will develop an Unbalanced Package.

Battery Management Analyzer Systems are so much more efficient than the so called “ smart chargers “. A smart charger can tell you that a battery is ready when it reaches its full voltage and still possibly be below the correct capacity level. A Battery Management Analyzer System will not tell you that a battery is ready until it is at 100 % of it’s full capacity level!

Recycle facilities for any chemical type of battery cells and packs. We are aware of 2 battery recycle companies in the USA that meet every requirement if the EPA.

We work with:
Inmetco
John A. Patterson or
John Liotta
P. O. Box 720
Ellwood City, PA 16117
412-758-2801

John did an article with a production company (we supply battery packs and chargers for) on recycling batteries and the environment and it was aired on the Discovery Channel. He may not remember me, but We were the battery assembler that Discovery had contacted for another article on recycling.

Alkaline Cells: Lithium Primary Cells:

Alkaline battery cells are a very good choice for many products except that they are a throw away type cell which is not environmentally conscious. The user can help by searching out a battery recycle facility.

The alkaline chemistry is designed for use with low or medium current drain applications. This chemistry is designed to “re-energize” itself over a short period of time. A fully charged alkaline cell would give off 100% of its capacity on the first use. When the power drain is disengaged the alkaline cell will begin to re-energize up to a % of the original charge capacity.

This cell is designed this way by the use of particular chemical makeup’s that interact between themselves with no outside assistance.

They are not a rechargeable battery cell, but do energize themselves each time they are used.

Of course, the re-energize process and end result are directly related to the amount of available capacity per each use. This is why an alkaline battery will last so long, as re-energize is relevant to available chemical action.

The Carbon Zinc models come in standard to heavy duty and are not designed to re-energize themselves at all. The heavy duty carbon zinc batteries are designed for high discharge applications like toy products and halogen flashlights or flashlights that are kept on for extremely long duration’s with no turn off points.

An alkaline battery cell would have no opportunity to re-energize and thus the heavy duty carbon zinc models are more cost effective in high drain applications, but still should be recycled for their material content and preserve nature for our future Family's.

Lithium, Primary:
Lithium cells for 9V applications can come in two forms, coin cell and cylindrical.

A lithium coin cell is designed for very long term low drain rate.
A lithium cylindrical cell is designed for a very heavy high discharge rate. Each has an application and this is directly related to which of the two cells is used for the 9.0V batter pack.

A 9.0V lithium battery pack built with a coin cell would be appropriate for monitors where a 9.0V lithium batter pack built with cylindrical cells would be more appropriate for a high discharge alarm.

There is also a difference in the cost of the manufactured product. Ultralife manufacturers a very good product and of course we sell Ultralife Brand Cells.

Nickel Cadmium 9 Volt Battery:
There is also a third alternative 9.0V batter pack and it two needs some clarification. The third is a nickel cadmium battery pack. Remember, 9.0V battery pack is really a style of battery. Depending on the chemical make up and the manufacturing technique, they will range from 7.2V to 8.4V and the capacity will range from 80 to 120 mAH.
Nickel cadmium 9.0V battery packs will actually be either (7.2V 84mAH or 100mAH) or (8.4V 100mAH or 120mAH).

Like all other chemical type 9.0V battery packs, these to are assembled using either coin cells or cylindrical cells.

In the Medical Field:
The preferred choice nickel cadmium battery pack for TENS unit will be a unit that is 8.4V110mAH. You do not usually find the 8.4V110mAH 9.0V battery pack on the retail consumer shelf. What you do find on the consumer shelf will show you the voltage of that cell, but, will NOT usually show you the milliamp Per Hour Readings which are almost always 7.2V84mAH. A significant difference in performance with a very insignificant difference in cost.

That is because in retail the nickel cadmium rechargeable battery cells and packs the consumer is supplied with are almost always the least expensive battery cell possible allowing for the highest possible amount of margin for the reseller. The reseller usually supplies the smallest capacity possible of each particular cell. Most retailers are not aware of any difference and Consumer USA is certainly not aware of any options. Battery cell manufacturers have enjoyed this situation for as long as the technology has been exposed to the consumer. Consumers and most resellers have not been educated on what they should expect from their battery cell or pack product.

Rathbone Energy Systems, Inc.,is capable to manufacture very good quality wall “smart” chargers for rechargeable 9V battery packs and we can also manufacture multi-port 9.0V battery management chargers for medical service centers or TENS rental facilities and manufacturers.

The only real draw back to rechargeable battery packs is that neither the medical manufacturer, reseller or consumer has ever been educated on or had access to information on the use and care of rechargeable battery packs. They are the most cost effective if the proper unit is purchased and used properly as suggested in our information on the proper use and care of rechargeable battery packs.

Additional Technical Information Quoted from other authorities in the field of battery cells, analyzers, and Chargrs: (Including Memory, Heat, Trickle Chargers, Alternate Charging Methods)
The below paragraphs were pulled or borrowed from various technical manuals or magazine articles to enhance what we have to say or reference on rechargeable battery cells and packs.

Actually, the “memory effect” myth about Ni-CD batteries has been pretty well debunked. Turns out that a memory effect can only be demonstrated under very carefully controlled lab conditions, where the cell is slightly discharged hundreds of times to exactly the same discharge point. Otherwise it does not exist.

The most damage done to Ni-CD cells by the memory effect is when users attempt to fully discharge the cells to avoid the mythical effect, and then drive it into reverse polarity, damaging the cells. Sorry we don’t have references with us on this. There was an article in the past years in QST (a ham radio magazine, published by the (American Radio Relay League) about this, and a few years back there was an item in QST Technical Correspondence from a battery engineer at Goul explaining that memory effect in Ni-CD's does not exist.

The myth is quite popular though. We have seen ads for fancy microprocessor controlled Ni-CD charges that carefully do a deep discharge before each charge.

Every so often, The Subject that Won’t Die returns to life. One of these is the “memory” effect that Ni-CD cells are supposed to be subject to. It turns out that there isn’t such a thing except in very rare cases.

From Nickel-Cadmium Battery Application Handbook, Second Edition 1975...
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7.1.3.1 Memory effects

Temporary effects on discharge voltage levels at any point during the discharge period, or an apparent reduction in capacity to a predetermined discharge voltage cutoff point, are developed in the battery system from repetitive use patterns. If the battery is discharged to random depths of discharge, and overcharged for random amounts of overcharge time, and subjected to various duty cycles, these temporary effects will not manifest themselves. The following paragraphs will discuss the factors and causes of these temporary memory effects.

Sealed cells subjected to a repetitive depth of discharge under certain cycling conditions may exhibit an apparent temporary loss of capacity. This phenomenon, sometimes referred to as “memory”, was first noticed in a satellite where the cell received a very precise charge/discharge regime using only a small portion of the available capacity over and over again. If the cell experiences such a series of repeated partial charge and discharge cycles of exact magnitudes, the cell may become so conditioned that it will deliver to the normal end-of-discharge voltage only slightly more capacity than has been required of it during these preceding repetitive cycles. Thus, if the discharge cycles are short, the cell capacity may be temporarily shortened to coincide with the discharge capacity previously experienced during the repetitive discharge cycle. The complete discharge voltage profile of a “Memorized” cell may appear as portrayed in Figure 7-3. This is more likely to occur when the overcharge coefficient is small, the rate of discharge is high, and/or the temperature is elevated. This effect is also more significant when the cutoff voltage is above 1.0 volt at the C rate.

If the cell is subjected to a deep discharge and then recharged, this “memory” is erased and nearly all of the original cell discharge energy is regained.

It must be emphasized that the “memory” effect does not manifest itself when the battery is discharged to random depths of discharge or overcharged for random amounts of overcharge time as is typically the case in most applications...
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Compare this explanation with their third edition (1986):
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4.5.3 Voltage Depression (This would apply to trickle (overnight) chargers)

The effects of elevated charge temperature on the immediate cycle capacity of the cell have been discussed in Section 3.2.1 and 4.3.3.1. Cells exposed to overcharge for very extended periods of time, particularly at elevated cell temperatures, may develop an additional shortcoming called VOLTAGE DEPRESSION. This phenomenon is one in which the cell voltage is depressed approximately 150 mV below the normally expected values which were calculated on Figure 4.19. This depression affects Eo and is independent of discharge rate. This depression effect initially appears on the discharge voltage curve near the end of discharge. With extension of the overcharge time (non-discharge) of the cell, this depression progresses slowly toward the mid-point and beyond. Accompanying this effect of depression in the voltage dimension of the curve is an actual slight increase in the capacity dimension as illustrated in Figure 4.21. This depressed voltage effect is an electrically reversible condition and disappears when the cell is completely discharged and charged (sometimes called conditioning). It thus appears only on the discharge following a very extended overcharge. It will reappear if the extended overcharge is repeated.

The phenomenon which causes this depressed voltage is continuous overcharging of the active material of the electrode. The effect is erased by discharging and recharging that portion of the active material which has experienced the extensive overcharge. For this reason the depressed voltage effect in the discharged portion of the curve is erased by the very act of observing it, when the discharge is carried beyond the first knee of the depressed curve. Complete discharge, and subsequent full charge, essentially restores the curve to its normal form.

The reversibility of this effect is probably the very characteristic that gives rise to the misnomer MEMORY. When cells are subjected to continuous charge/overcharge, with only modest discharges (repetitive or otherwise), the reversibility of the effect actually prevents the voltage depression from occurring in that portion of the electrode active material which is cycled. The voltage depression phenomenon is, however, not erased from that portion of the electrode material which has been subjected to continuous overcharge but NOT discharged. In this situation, whenever the cell is discharged deeper than recent previous discharges and reaches the beginning of the previously uncycled material, the voltage may decrease 150 mV per cell. This misleads the observer into believing that the discharge is at the knee of the normal discharge curve and erroneously concluding that the cell remembers and, thus, delivers only the amount of capacity previously repetitively used. Instead, the phenomenon is actually related only to extended overcharging and incomplete discharging, not repetitive shallow cycling. This is because that portion of the

electrode material which has experienced overcharge and not been discharged for an extended period of time slowly shifts to a more inaccessible form.

The depressed voltage effect can of course cause loss of useful capacity in those application cases where a high cutoff voltage prevents complete discharge of the minimum capacity cell in the battery. If voltage depression has occurred, complete discharge requires continuation down through the depressed knee to that voltage level which keeps all the electrode material active...

By the way, when these guys talk about overcharge, they talk about charging at C/10 for weeks or months.

Using a standard 16 hour charger for a day or two do not excite them. In this case, the only problem they see would be the elevated temperature that the cells would be subjected to.

Now, temperature... that’s another problem. I talked to four applications engineers at Gates and each one stressed that temperature is the killer. They say that each 10 degree C over the life of the cell reduces cell life by one half.

TEMPERATURE THAT’S THE BIG THING.
GE found that while there may be some very infrequent cases of a true “memory”, the vast majority of problems seen with this type of cell were due to improper selection of the cell for a given application (improper choice of cell for expected discharge characteristics), and, more importantly, improper charging of the cells. Ni-CD cells, in contrast to lead-acid types, are *not* suitable for constant “trickle charging” (unless some provision is made for sensing cell voltage/temp, or *very* low current is used), which is a mode seen very often in consumer applications. Improper charging characteristics will do more than anything else to degrade overall cell performance.

To quote from one technical reference which discusses the subject (Varta “Sealed Ni-CD-Batteries Product Range and Technical Handbook”, 1987, section 2,

“Characteristics of Sealed Ni-CD Batteries”) :“...Electrical stress and charging methods have a vital impact on service life...The best way to ensure long service life and trouble-free operation is to follow the charging instructions carefully. Sealed Ni-CD batteries may be stored for years regardless of the charge state they are in.”

Rathbone Energy , Inc., states an opinion that when Ni-CD cells are stored for long periods of time they must then go through an exercise routine in order to tone or build the cell strength just as a person would do to build or tone their body muscle.

And, from the aforementioned GE note (General Electric Technical Marketing
Flash TMF 8517):
“To the well-informed, however, `memory’ is a term applied to a specific phenomenon encountered very infrequently in field applications...GE has not verified true memory in any field applications, with the single exception of the satellite application noted above. Lack of empirical evidence notwithstanding, memory is still blamed regularly for poor battery performance that is caused by a number of simple, correctible application problems.”

Gould Inc., Portable Battery Division, had this to say:
“A nickel-cadmium cell which has been charged for an extended period of time exhibits a reduced operating voltage on subsequent discharge. The characteristic [has been referred to as] `voltage depression’, `memory’, or `stepped discharge voltage.’”

Thus, while there is a possibility of a true “memory” in Ni-CD's, it is *extremely* rare, as it manifests itself only under some very specific and unlikely conditions, one being that the cell is repeatedly discharged to the same level, *within no more than 2-3%* (which is what happened in GE’s one example - the cells in the satellite assembly were being discharged under very precise computer control).

It may have been overstating the case slightly to say that there is “no” memory effect possible, but done so in the interests of simplicity. It is also far, far closer to the truth than the current level of understanding, which has people actually wasting discharge cycles for no good reason.

The operating characteristics of a Ni-CD cell are very basic in nature. During charge, only current and cell temperature are critical. Discharge may occur at any current rate until the cell terminal voltage falls below 1.1 volts, but the cell temperature rise must not cause the cell electrolyte to boil (gas). When connected in a pack, the pack must be unloaded when the individual cell voltage falls to 1.1 volts to prevent reverse charging of the lowest voltage cell in the pack.

Few applications discharge cells at an excessive high rate where gassing becomes a problem, with the exception of toy electric cars (these are “toys” for men). Cells designed for this application
usually have larger than average plate area and large connecting tabs to support the higher peak current. Cell temperature is kept below the critical value by selecting the cell capacity such that the cell will dissipate its charge before gassing occurs.

In essence, the toy car runs continuously with a nearly zero series load resistance allowing the cell temperature to rise near critical just as cell discharge is reached.

The following brief notes will further amplify an understanding of Ni-CD cell characteristics.

1. Ni-CD's are very easily damaged due to gas pressure caused by over-charging at high charge rates. Unfortunately, Ni-CD's do not have a positive indicator for indicating the state of charge.

It is up to the user to estimate the relative charge state. Typically, the charge rate is calculated at C/10 where C equals cell capacity and the 10 represents hours for charging. At C/10, a nominal or normal charge would occur. A fast charge can be accomplished, cell design permitting, by changing the ratio, i.e., 5C/2.

2. Cell temperature does rise at the completion of the charge cycle, particularly at high charge current values, and can be used as a charge completion indicator. At the moment of temperature rise, the charge current must be reduced immediately to prevent excessive gas pressure build-up. Some chargers monitor the cell temperature and reduce the charge current to a small sustaining value. For 500mAHcells, the sustaining value is typically between 10-25mAH, or just enough current to compensate for the chemical change ( internal current leakage).

3. Pulse charging of Ni-CD's, Ni-MH, Li-ON is most preferred as it is more efficient than a steady-state current value. Steady state current creates gas bubble formation on the plates of the cell, while pulse current tends to create fewer gas bubbles allowing the charge to be more uniform across the plate area. The charge uniformity is enabled by gas bubbles being moved around due to current pulsation’s. Bubble movement allows more plate area to be exposed during charge. Pulse charging also creates less of a temperature rise. The charge rate still has to be calculated as a function of C/10 during each charge pulse to determine total charge time (The accumulated charge is equal to the sum of the charge area under the pulse curve).

4. Older Ni-CD cells would not accept high charge rates above C/10 an would develop electrolyte seal leakage at attempted higher charge rates. A leaky seal, in any case, means the eventual loss of the cell. Newer cells, as used in most handheld radio applications seem to tolerate high charge rates without developing cell leakage as long as the temperature is controlled (kept low).

5. In the event corrosion around the seal of a cell develops, the corrosion can be removed. Wipe the corroded area with a vinegar soaked cotton swab. Use an ample amount of liquid and dry the cell with a tissue. Keeping the cell clean allows it to be used until it fails completely. Take note that weeping cells can cause corrosion problems if they are not inspected and cleaned regularly.

6. Discharge of a Ni-CD is critical only if the cell is under a load. When loaded, the cell voltage should not be allowed to drop below 1.1 volts which is just over the edge of the discharge end of the curve. Allowing the cell to drop to 1.0 volt or less while under load may cause permanent plate/electrolyte damage.

The result would be a loss of cell capacity. Of course, a loss also takes place naturally with age which limits the number of charge-discharge cycles the cell is capable of supporting before it is exhausted.

7. Unloaded cells may be stored almost indefinitely and allowed to discharge to whatever cell terminal voltage the cell can maintain on its own.

When putting a previously stored cell into use, charge the cell, at least the first cycle, at C/10 for 12-14 hours. Shelf life of a cell is usually a function of how fast nickel whiskers (crystallization) develop internally that can short the cell. Two methods have been proposed as a way of extending cell life when whisker formation is of concern.

a) Cycle the use of the cell/pack periodically. It is believed that the rate of

whisker formation is reduced when cells are charged and discharged periodically.

b) Allow the cell to sit on the shelf as long as needed and if a whisker short should occur, blast it away with a high current pulse from a capacitor or other source. It has been observed that once whisker growth/shorting begins, it can not be permanently stopped. It is like a mold or fungus.

8. It has been observed that the terminal voltage across a charged Ni-CD cell will increase as the cell ages. Using this observation, the life expectancy of a cell can be evaluated and monitored. As an example, a new/fresh cell will exhibit a terminal voltage of 1.25 volts while an old cell will exhibit, say, 1.5 volts. It is believed that the cell dehydrates with age and the rising voltage is a function of the increase in cell impedance.

Many hints and kinks have been published regarding the nature and care of Ni-CD's and all point to the fact that Ni-CD's require user TLC to obtain long cell life. The bottom line is that the user must pay attention to how the cell is being treated.