During our recent webinar titled "How Many Cycles Can I Expect from My Battery?" we were unable to answer all of the questions that came in during the Q&A section within the given time. One of the questions stood out from the rest so we wanted to share the question and answer on our blog.
Question - Is battery charging/discharging at a given current more or less life-limiting at different temperatures? Example: Charging at higher current when the battery is cool vs when it is warm.
There are two answers depending on the charge rate:
If you are charging or discharging a battery at a low rate, <0.5°C, then charging or discharging at higher temperatures will age the battery faster due to the exponential aging effects of elevated temperatures. The converse is true down to 0°C. Below 0°C lithium plating occurs, which causes permanent capacity loss.
If you are charging near 1°C or greater rates, a number of factors come into play. Charging or discharging at a high rate and a high temperature the battery's cycle life is adversely affected. Because the battery only remains at the elevated temperature for a short duration of time, the effect on it is miniscule. This is due to a fast charge time and a minimal amount of accelerated aging if the battery spends most of its' life at lower temperatures.
At low temperature high discharge rate is limited to the high internal impedance of the cell and is not an issue on cycle life.
However, at low temperature, caution MUST be used if using a high charge rate. This is where big problems can happen because Lithium plating can happen above 0°C when subjecting the cell to a high charge current. The high charge current causes an IR drop in the cell due to the cells high internal impedance. The higher the charge current, the higher the internal voltage drops. The problem occurs when the IR drop exceeds the zero-anode potential current. This becomes much worse as the cell ages. At low temperatures be sure to reduce charge current.
If you would like to view the "How Many Cycles Can I Expect from My Battery?" webinar in its entirety, click the link.
* Image Source: www.TI.com/battery