Nickel-based Batteries

The following section describes nickel-based batteries, and we begin with nickel-cadmium (NiCd), an older chemistry for which extensive data is available. Much of these characteristics also apply to nickel-metal-hydride (NiMH), as these two systems are close cousins. The toxicity of NiCd is limiting this solid and robust battery to specialty applications.

Nickel-cadmium (NiCd)

The nickel-cadmium battery, invented by Waldmar Jungner in 1899, offered several advantages over lead acid, but the materials were expensive and the early use was restricted. Developments lagged until 1932 when attempts were made to deposit the active materials inside a porous nickel-plated electrode. Further improvements occurred in 1947 by trying to absorb the gases generated during charge. This led to the modern sealed NiCd battery in use today.

For many years, NiCd was the preferred battery choice for two-way radios, emergency medical equipment, professional video cameras and power tools. In the late 1980s, the ultra-high-capacity NiCd rocked the world with capacities that were up to 60 percent higher than the standard NiCd. This was done by packing more active material into the cell, but the gain was met with the side effects of higher internal resistance and shorter cycle.

The standard NiCd remains one of the most rugged and forgiving batteries but needs proper care to attain longevity. It is perhaps for this reason that NiCd is the favorite battery of many engineers. Table 1 lists the advantages and limitations of the standard NiCd.


Fast and simple charging even after prolonged storage

High number of charge/discharge cycles; provides over 1,000 charge/discharge cycles with proper maintenance

Good load performance; rugged and forgiving if abused

Long shelf life; can be stored in a discharged state

Simple storage and transportation; not subject to regulatory control

Good low-temperature performance

Economically priced; NiCd is the lowest in terms of cost per cycle

Available in a wide range of sizes and performance options


Relatively low specific energy compared with newer systems

Memory effect; needs periodic full discharges

Environmentally unfriendly; cadmium is a toxic metal and cannot be disposed of in landfills

High self-discharge; needs recharging after storage

Table 1: Advantages and limitations of NiCd batteries

Nickel-metal-hydride (NiMH)

Research of nickel-metal-hydride started in 1967; however, instabilities with the metal-hydride led scientists to develop the nickel-hydrogen battery (NiH) instead. Today, NiH is mainly used in satellites.        

New hydride alloys discovered in the 1980s offered better stability and the development of NiMH advanced in earnest. Today, NiMH provides 40 percent higher specific energy than a standard NiCd, but the decisive advantage is the absence of toxic metals.

The advancements of NiMH are impressive. Since 1991, the specific energy has doubled and the life span extended. The hype of lithium-ion may have dampened the enthusiasm for NiMH a bit but not to the point to turn HEV makers away from this proven technology. Batteries for the electric powertrain in vehicles must meet some of the most demanding challenges, and NiMH has two major advantages over Li-ion here. These are price and safety. Makers of hybrid vehicles claim that NiMH costs one-third of an equivalent Li-ion system, and the relaxation on safety provisions contribute in part to this price reduction.

Nickel-metal-hydride is not without drawbacks. For one, it has a lower specific energy than Li-ion, and this is especially true with NiMH for the electric powertrain. The reader should be reminded that NiMH and Li-ion with high energy densities are reserved for consumer products; they would not be robust enough for the hybrid and electric vehicles. NiMH and Li-ion for the electric powertrain have roughly one-third less capacity than consumer batteries.

NiMH also has high self-discharge and loses about 20 percent of its capacity within the first 24 hours, and 10 percent per month thereafter. Modifying the hydride materials lowers the self-discharge and reduces corrosion of the alloy, but this decreases the specific energy. Batteries for the electric powertrain make use of this modification to achieve the needed robustness and life span.

There are strong opinions and preferences between battery chemistries, and some experts say that NiMH will serve as an interim solution to the more promising lithium systems. There are many hurdles surrounding Li-ion also and these are cost and safety. Li-ion cells are not offered to the public in AA, AAA and other popular sizes in part because of safety. Even if they were made available, Li-ion has a higher voltage compared to nickel-based batteries.

Consumer Application

NiMH has become one of the most readily available and low-cost rechargeable batteries for portable devices. NiMH is non-toxic and offers a higher specific energy than NiCd. Battery manufacturers, such as Sanyo, Energizer, Duracell and GP, have recognized the need for a durable and low-cost rechargeable battery for consumers and offer NiMH in AA and AAA sizes. The battery manufacturers hope to persuade buyers to switch to rechargeable batteries and reduce the environmental impact of throwaway primary cells.

The NiMH battery for the consumer market can be viewed as an alternative to the failed reusable alkaline that appeared in the 1990s. Limited cycle life and poor loading characteristics hindered its success.

What is of ongoing concern to the consumer using rechargeable batteries is the high self-discharge, and NiMH behaves like a leaky basketball or bicycle tire. A flashlight or portable entertainment device with a NiMH battery gets “flat” when put away for only a few weeks. Having to recharge the device before each use does not sit well. The Eneloop NiMH by Sanyo has reduced the self-discharge by a factor of six. This means that you can store the charged battery six times longer than a regular NiMH before a recharge becomes necessary. The drawback is a slightly lower specific energy compared to a regular NiMH. Other NiMH manufacturers such as ReCyko by GP claim similar results.

Table 2 summarizes the advantages and limitations of industrial-grade NiMH. The table does not include the Eneloop and equivalent consumer brands.


30–40 percent higher capacity than a standard NiCd

Less prone to memory than NiCd

Simple storage and transportation; not subject to regulatory control

Environmentally friendly; contains only mild toxins

Nickel content makes recycling profitable


Limited service life; deep discharge reduces service life

Requires complex charge algorithm

Does not absorb overcharge well; trickle charge must be kept low

Generates heat during fast-charge and high-load discharge

High self-discharge; chemical additives reduce self-discharge at the expense of capacity

Performance degrades if stored at elevated temperatures; should be stored in a cool place at about 40 percent state-of-charge

Table 2: Advantages and limitations of NiMH batteries


On February 15, 2011 at 10:02am
Muhammad hanif wrote:

our client have old Nickle Cadium battery and have obtained nicke cadium plate and after obtained nicke cadium plate melt in furnace and made ingot both items.
we we are interested seprate nicke and seprate cadium in chemical process or magnet sepraction or other process.pls advise us

On January 10, 2012 at 5:22pm
Bill Heintz wrote:

Can you add something on this page about Nickel-Iron (NiFe) alkaline batteries (Edison batteries).

I have an 3rd edition copy of Electric Circuits and Machines by Eugene C. Lister that only devotes a page or so of details.  There and there are a few companies that still sell them;  perhaps they are still a viable option for certain applications.

On January 21, 2012 at 2:45pm
Arild Jensen wrote:

NiFe batteries are experiencing a resurgence of interest because of their ability to store large amounts of energy for off-grid installations and the relatively benign environmental impact compared tp lead plated sulphuric acid electrolyte batteries. Indications are these batteries can remain in use for decades thus also reducing sending them to a land fill site or requiring expensive recycling facilities.

On January 26, 2012 at 9:53am
Bill Heintz wrote:

The NiFe battery is already covered in the “Battery Types / Alternate Battery Systems” Section.

On March 10, 2012 at 10:49pm
Herald wrote:

I am looking for data on industrial nickle cadmium battery heat emission during charging and discharging

On March 11, 2012 at 1:13pm
Raydel Crego wrote:

I was going to buy your book because of all the expert information it contains,but was really hopping it would include the new generation NiMH low self discharge batteries and learn all the detais about them,it seems great not having to trough the endless total discharge/charge cicles to condition the regular batteries,plus the long shelf life they seem like the cutting edge in technology.Will you be publishing information on these newer NiMH batteries soon

On March 13, 2012 at 12:17pm
Dobra Georgian wrote:

NiMH batteries are new for me and I want to find some tips for charging and preserving them,I announce you that I have 4 AA batteries Energizer of 2500 mAh and 4 Sanyo 2700 mAh normal (not LSD) and 4-channel smart charger that charge all batteries fully discharged in 3 hours:
1. keeping the battery empty for a week or longer is damaging it ?
2. if the battery is at 70% of capacity and I begin charging , is this damaging it ?
3. how to prevent self discharge as much as possible
4. what is the best use on low temperatures (sometimes if I am outside and is cold my camera wont want even to start and if I come inside the batteries restores and the camera is working ; is there a way to make the camera work at that low temperatures (0 C) not fully charged ? )
5. the charge cycle of NiMh is the same as charge cycle of Li-Ion (0% to 100% or 2 times 50% to 100% etc .)?

thank you !

On March 22, 2012 at 8:58pm
Glen Nelson wrote:

Battery operated power tools.

I have been using battery operated power tools for a long time. Why is it that the lithium powered tools require new batteries more often? They are also more expensive. I like the older NiCad technology for tools. I have NiCad batteries purchased in 2004 that are still performing close to new. The trick w/NiCad is to use it, then cool it, then charge it. I don’t overheat them. My first lithium tool kit was purchased in 2008 and NONE of of the batteries from that era work anymore. The lithium tools have grunt and long run time between charges but they die out of the blue and only last a couple of years.

Should I take a chance and buy a new set of Lithium? have they improved the shortcomings on the batteries listed above?

On June 15, 2012 at 2:29pm
John wrote:

Can somebody tell me the advantages and disadvantages of higher and lower MAH ratings? I read somewhere that higher MAH is not always better. Thanks.

On October 21, 2012 at 10:41am
Peter Valúch wrote:

Hello, I am doing a research about batteries used in hybrid cars. And I need to put the references on my reference list. I would like to know who is the author of this article.
Thank you very much.

On October 21, 2012 at 5:06pm
photon wrote:

Hello, Do NiMH need calibration ?Thank you!

On January 15, 2013 at 6:51am
BOB MEUSE wrote:

I have a recording machine with a built-in charger for a sealed NiCad battery pack.
The battery pack has just been rebuilt with Ni MH cells.
Will the charger or the battery be damaged now that the battery is Ni MH?

On January 25, 2013 at 10:32am
Mike Streeter wrote:

I performed a test discharge of a battery pack consistng of 7 Sanyo HR-3U (NiMH 2700 mAh) batteries in series.  The discharge was at a rate of roughly 0.3 C.  Initial voltage/current was 8.5 volts and 0.75 Amps.  Test circuit consisted of the battery pack in series with a 12 ohm resistor and an Ammeter.  The battery pack discharged in a linear fashion for an hour and then the voltage across the battery pack ramped up rapidly to 13 volts.  I discontinued the discharge for an hour and then reconnected the circuit.  Battery voltage was 8.0 volts.  Any ideas what could cause the Battery voltage to ramp up to 13 volts?  I have reviewed technical info on these Batteries and have not found any thing that describes this kind of effect on a discharge cycle.

On March 6, 2013 at 1:13pm
Slocket wrote:

BOB MEUSE wrote:

I have a recording machine with a built-in charger for a sealed NiCad battery pack.
The battery pack has just been rebuilt with Ni MH cells.
Will the charger or the battery be damaged now that the battery is Ni MH?
Most smart chargers look for the -Delta V drop of NiCd when they are close to 100% full charge. NiMH does not have that drop (much) you could overcharge them. Make sure your charger is smart enough to stop charging anyway - it could have different mechanism and thermal shut off etc to prevent over charging. Give it a charge cycle and see how hot they get, hot battery is sure indication of overcharging which tends to absolutely ruin Lithium battery but NiMH are tougher but do not let them overcharge to get hot. Get an real NiMH charger if in doubt or hot battery after a charge session.

On May 10, 2013 at 7:04am
Achim wrote:

I have an electric tooth brush with a NiCd battery inside and use it now for about nine yeras with estimated 500-800 full charge discharge cycles - still working fine with only a moderate capacity loss. The newer model of my wife has a NiMH battery which cannot be exchanged - I expect a much shorter life and doubt that throwing the whole tooth brush after few years of use is more envrontally friendly. Why then do manufacturers withdraw the NiCd variants ?

On May 14, 2013 at 6:32am
Rob Davidowitz wrote:

This may be a silly question so please forgive my battery ignorance.

Is there a way of measuring the remaining capacity in MaH by using a multimeter?

Eg: To measure voltage, I attach the positive lead to positive pole and same for negative and read Voltage - No problem

How do I measure the X of 2100Mah left in the battery?


On June 7, 2013 at 7:34am
thumar rushik wrote:

please give me information about Charging voltage and current for nickel based battery, because over voltage charging battery ay be explode the battery .

On August 11, 2013 at 1:45pm
TravisE wrote:

The article is either wrong or not telling the true story on the so-called memory effect and/or needs some citations. Most sources I’ve read say that this ONLY applies to sintered plate NiCd cells that are repeatedly discharged to PRECISELY the same SoC (which in itself is difficult enough to achieve in practice) and charged WITHOUT any overcharge. This is exceedingly unlikely to happen in any consumer cells even if they were of the sintered plate type. The only effect I have personally ever seen with nickel-based batteries that involve reduced capacity has been permanent degradation due to defective or worn out cells. This is NOT a memory effect.

On September 18, 2013 at 9:22am
Crimson Halo wrote:

Please update this page! Low self-discharge NiMHs have evolved and have really come into their own ... they’re better than yesteryear;s NiMHs and give at least the same performance if not more, the discharge curve is relatively flat, and in my own experience I know they can take hundreds if not thousands of cycles.

On September 20, 2013 at 11:12am
PFWAG wrote:

The newer NiMh batteries, like Sanyo/Panasonic’s Eneloop brand, have VERY LOW self discharge rates with only a small hit on capacity..If I remember correctly, they retain about 70% of power after 3 years.  Great in your flashlights and cameras that might sit for a long time without the batteries being re-charged..

On November 16, 2013 at 8:25am
Forncett wrote:

Nickel isn’t toxic? Are you kidding me?? Take a look at the video in Great Railway Journeys of the World where the travelers go deep into a remote part of Russia and encounter mile upon mile of devastation caused by nickel mining that’s poisoned everything within its reach, and permanently so far as the lifespan of the human race is concerned. Or if that’s too hard, Google “is nickel toxic?”...

You’ve got a great website that my power design-engineer and technical editor roles fully appreciate - please don’t pollute it with misinformation!

On December 27, 2013 at 8:17pm
Ludwig Merk wrote:

There is a lot of writing about capacity, current, nominal voltage, recharging current/amps - but whats about recgarging voltage?
I measured chargers for single cell and power tool packs, both are recharging with 5.0 volts regardles if its for 1 cell or a pack of 10 cells (=12V pack) in a row.
It it always 5.0 volts?

On January 19, 2014 at 8:20am
senthil wrote:

how many nickel% is in nickel cadium batteries. please tell the detail.