Effects of C Rating on Battery Life

batteriescurrentdischargelifetimelithium ion

A polymer lithium ion battery is rated at 3.7v, 6600mAh and a maximum discharge current is specified at 3.3A. I take it this means the battery can be discharged at 3.3A and last for two hours since 6.6Ah/3.3A = 2 hours.

However, in addition to the above specifications, the battery has a nominal capacity of 6600mAh at 0.2C discharge. How does this extra bit of information affect my above calculation? I.e. How will it affect the battery life for a given current draw?

Best Answer

What the extra bit of information means is that to realize the full 6600mAh capacity of the battery you would have to limit the discharge rate to 1320mA. That gives a typical usage time of 5 hours at that load.

When you increase the discharge rate you will change several things.

  • Battery cell temperature
  • Total realized capacity
  • Overall lifetime of the battery