Battery FAQS

1、What is the difference between Lithium batteries and Lithium Ion batteries?
2、What are the advantages of Lithium Ion batteries?
3、Are Lithium Ion batteries available in standard sizes like AA , C or D cell size?

1、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.

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2、What are the advantages of Lithium Ion 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 discharge rate than other types of rechargeable batteries.  This means that once they are charged they will retain their charge for a longer time than other types of rechargeable batteries.  NiMH and NiCd batteries can lose anywhere from 1-5% of their charge per day, (depending on the storage temperature) even if they are not installed in a device. Lithium-ion batteries will retain most of their charge even after months of storage.

So in summary; lithium-ion batteries can be smaller or lighter, have a higher voltage and hold a charge much longer than other types of batteries.

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3、Are Lithium Ion batteries available in standard sizes like AA , C or D cell size?

No, Lithium-ion batteries are not available in standard sizes. We believe this is because it would be too easy for users to inadvertently put them in a charger not designed for Lithium-ion batteries creating a potentially dangerous situation. (If an alkaline battery is put into the wrong charger it might leak or even burst, but a lithium-ion battery put into a NiCd or NiMH charger not designed for lithium-ion, might ignite. Also, because Li-ion batteries operate at much higher voltage (typically 3.7V per cell)  than the 1.2 to 1.5V of most cell batteries, designing a 1.5V lithium-ion cell would be expensive.

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1、Which are better, NiCd batteries or NiMH batteries?
2、Do NiMH batteries have memory effect?
3、What is the shelf life of a NiMH battery? 

1、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 when considering power sources for electronic devices like digital cameras or portable music players. (If you are choosing a battery to drive a high torque power screwdriver, then NiCds can outperform NiMH).  NiMH batteries require more sophisticated chargers than those typically used for NiCd batteries.  But smart chargers designed especially for NiMH batteries are now readily available.

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2、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 NiCd section immediately above this one). Most users of NiMH batteries don't have to be concerned with this voltage depletion effect.  But if you use a device say a flashlight, radio, or digital camera for only a short time every day and then charge the batteries every night, you will need to let the NiMH (or NiCd) batteries run down occasionally.

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3、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.  Stored at a lower temperature they self discharge at a lower rate (Self discharge chart available soon).

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