About Lithium-Ion (Li-ion) Battery
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.
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 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.
Protected vs. Unprotected Li-ion batteries
The primary difference between the Protected and Unprotected batteries is that the protected batteries have a
small circuit board, typically on the bottom of the battery, that stops the charging or discharge of the battery in
certain circumstances. Some of the circumstances in which the circuit include: Over-Charge, Over-Discharge,
Short-Circuit, and in some cases, overheating. Over-charge protection cuts off the charging process at 4.2V,
while over-discharge protection cuts off the battery at 2.8V. Protected Li-ion batteries usually are about 1.5~2 mm
longer than their equivalent unprotected Li-ion cells, due to the circuit board inside.
What is the best way to store Lithium Ion batteries?
Lithium-ion batteries can hold a charge for many months. It is best to store a lithium-ion battery with a partial or full
charge. Occasionally, a lithium-ion battery with a very low charge is stored for a long period of time (many months)
and its voltage slowly drops to below the level at which its built in safety mechanism allows it to be charged again.
If the battery is going to be stored for several months it's a good idea to take it out and recharge it after a few
months. Better yet would be to actually use the battery every few months and then leave it partially or fully
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