Battery Charging Efficiency Change With Age?

[geoheath]

We all know that as the lithium ion battery ages and accumulates charge cycles its capacity to store electricity is reduced. My question is, does the charging efficiency also decline? That is, does the ratio of energy in vs energy out also take a hit? Can someone direct me to a technical source that answers that question?

 

[michaelbmw]

Yes, but it is a minor effect. The effective series resistance of the battery increases with age, so the amount of charging energy that goes to heat increases.

As a battery ages, not only does it energy capacity decrease, but also its ability to delivery power decreases. The latter is due to increase in ESR which affects charging as well as discharge.