FAQ

What is the shelf life of a NiMH battery?

You probably mean to ask: What is the self discharge rate of a NiMH battery?  The rate of self discharge for any battery depends on the temperature at which it's stored.  Stored at 70 degrees F (20 C) NiMH batteries will lose up to 40% of their charge within a month.  If they are stored at a higher temperature, they will self discharge at an even higher rate.  NiMH batteries stored at a lower temperature self discharge at a [...]

What does mAh stand for?

mAh stands for milli Ampere hour or milli Amp hour.  It is a measure of a battery's energy storage capacity.  If you think of a battery as a small fuel storage tank, which in a sense it is, mAh a measure of how much "fuel" the battery holds.  (This is roughly comparable to using gallons to measure how much fuel a gas tank can hold.  The more gallons of capacity,  the more fuel the tank can hold.) With a [...]

Do NiMH batteries have memory effect?

Technically, NiMH batteries do not have a "memory effect", but strictly speaking neither do NiCds.  However NiMH batteries can experience voltage depletion, also called voltage depression, similar to that of NiCd batteries, but the effect is normally  less noticeable.  To completely eliminate the possibility of NiMH batteries suffering any voltage depletion effect  manufacturers recommend an occasional, complete discharge of NiMH batteries followed by a full recharge. NiMH batteries can also be damaged by overcharge and improper storage (see the [...]

Which are better, NiCd batteries or NiMH batteries?

For most electronic devices it is better to use NiMH batteries than NiCd batteries.  NiCd batteries use Cadmium, a highly toxic heavy metal, that can damage the environment if not disposed of properly. (They should be recycled not discarded).  NiMH batteries usually have a higher capacity than NiCd batteries of the same size.  Some people argue that NiCd batteries deliver faster discharge rates than NiMH batteries.  While this may be true under certain circumstances, the difference is not relevant [...]

Are batteries dangerous, how should I handle them correctly?

Batteries are only dangerous if handled incorrectly and proper maintenance is not followed. The hydrogen gas that batteries make when charging is very explosive. We have seen instances of batteries blowing up and drenching everything in sulphuric acid and sending jagged pieces of the poly propylene case up to 20 metres away. It only takes a small spark, flame or burning cigarette to set off a dangerous explosion. Therefore ignition sources must be kept well away at all times. [...]

What is the difference between Lithium batteries and Lithium Ion batteries?

There are several important differences. The practical difference between Lithium batteries and Lithium-ion (Li-ion) batteries is that most Lithium batteries are not rechargeable but Li-ion batteries are rechargeable.  From a chemical standpoint Lithium batteries use lithium in its pure metallic form.  Li-ion batteries use lithium compounds which are much more stable than the elemental lithium used in lithium batteries. A lithium battery should never be recharged while lithium-ion batteries are designed to be recharged hundreds of times.

Does overcharging cause damage?

Overcharging occurs when the total capacity removed has been replaced by recharging and the battery remains on charge. This overcharging creates excessive heat that can cause the battery plates within the cells to buckle and shed their active material. The battery will react to the overcharge by producing an excessive amount of hydrogen and oxygen. These gases are the result of the breakdown of the water molecules within the electrolyte. The water that has been displaced by overcharging can [...]

How are battery ratings used?

  How are battery ratings used? 1.  Amp-Hour battery rating: This is the common rating of a battery. Amp-hour rating of battery capacity is calculated by multiplying the current (in amperes) by discharge time (in hours). Amp-hour battery rating is commonly when describing sealed lead acid batteries used in UPS systems, emergency lights and wheelchairs. For example: a battery which delivers 2 amperes for 20 hours would have a 40 amp-hour battery rating (2 * 20= 40). 2.  Cold Cranking Amperage battery rating: [...]

What is the difference between Nickel Cadmium (NiCad) and Nickel Metal Hydride (NIMH) batteries? What is “Memory Effect?”

Both NiCad and NiMH batteries are rechargeable. The main difference between the two is the fact that NIMH batteries offer higher energy densities than NiCads. In other words, pound for pound, NIMH delivers approximately 30% more capacity than its NiCad counterpart. What this translates into is increased runtime from the battery with no additional bulk. NIMH also offers another major advantage: NiCad batteries tend to suffer from what is called a "memory effect". What this means is that when [...]

What are the advantages of Lithium Ion batteries compared to other rechargeable batteries?

Lithium-ion batteries have several advantages: They have a higher energy density than most other types of rechargeables. This means that for their size or weight they can store more energy than other rechargeable batteries. They also operate at higher voltages than other rechargeables, typically about 3.7 volts for lithium-ion vs. 1.2 volts for NiMH or NiCd. This means a single cell can often be used rather than multiple NiMH or NiCd cells. Lithium-ion batteries also have a lower self [...]