There are many types of lithium batteries. The 3 most common types of commercially available ones will be briefly discussed. They are;
Lithium ion (Li-ion)
Lithium Polymer (RC Lipo)
Lithium Iron Phosphate (Life PO4)
Lithium ion (Li-ion) batteries
These are the most common types used in consumer electronics like laptops, cell phones, power tools etc. They have the highest energy to weight ratios. These batteries are relatively safe, they won’t just burst into fire. They have long cycle lives. The shortest is about 300 discharge circles, and can reach as high as 1000 discharge circles. The most common workable form is the 18650 cylindrical cell ( 18mm dia. & 65mm height). They have nominal voltage of around 3.7V and a discharge-charge voltage range of 2.5V- 4.2V.
Lithium Polymer (RC Lipo) Batteries
These batteries can provide high discharge rates for long periods of time. They are used for equipment that require high discharge rates such as Remote control led drones, helicopters, cars, planes etc. These batteries are very cheap, cheaper than a typical lithium ion and life PO4 battery. They have very short cycle lives, about 200 recharge discharge cycles. They have a lower discharge – charge range of about 3V – 3.7V. They are very volatile and can easily burst into flames if not carefully handled.
Lithium Iron Phosphate (LifePO4)
LifePO4 battery cells are heavier and less energy dense than most lithium ion cells.
These batteries have the longest cycle life of all the common lithium battery cell types.
They have a nominal voltage of about 3.2 V per cell and discharge- charge voltage of 2.5V- 3.65V. The Best applications for LifePO4 cells are projects that require long cycle lives and high safety.
General information in Lithium batteries
Lithium battery cells when fully charged can read up to 4.2V and at its discharged state reads 2.5V. Lithium battery cells discharged below 2.5 V will cause irreparable damage to the cell. This is why Lithium batteries are fitted with a battery management system, BMS. The main function of BMS is to ensure that the battery is properly charged as well as to prevent overcharging and over discharging.