This weird belief by everyone, including manufacturers, that a battery shouldnt be charged to 100% is surely a strange one. we’ve all been driving cars with 12v batteries for quite a long time, but we’ve never been told to keep it at 9.6v for battery health, and they regularly charge at an estimated 14.4v. Have a read of this article, they do some good research into EV cultures, myths and facts
I question much of the logic in the link provided.
Each cell in a 12v lead acid battery should be 2.2V nominal and have no less than 12,6V when the enhine is not running. Withe the engine running, the alternators voltage regulator will keep the output between 13.5-14V with an optimal output of 13.8V, a float charge of 2.25 to 2.27/8 (can’t remener per cell. Any higher than that, the battery could be fried. A battery at 9.4V has 2 dead cells, even at 9.6V it wont hold its charge.
Charging lithium batteries like NMC and NCA to 100% continually will have a negative affect over time. The difference between the total capacity of the battery and the useable amount that can be drawn upon, is there so you don’t fully deplete every last bit of energy in the battery when driving, thereby damaging or shortening the life of the battery. The vehicle will come to a halt or go into limp mode long before this point is reached, this point is often below the guage showing 0%, hence the vehicle will travell a little further before it actually hits the buffer.
Letting the battery drop below 20% or even below 10% is rarely cause for concern. Permanently low states of charge below 20% for long periods of time, such as leaving the vehicle standing for weeks on end carries the risk of total discharge, Its easier for manufacturers state 20%, than waffle on in the small print nobdy reads,
Batteries like NMC NCA charged to 100% is actually 100%, frequently charging to 100% will negatively affect the battery longterm. Whils’t charging the useable battery capacity 20-80% or 0-80% you will only get 60 or 80% per charge cycle. Even charging 0-80% charge cycle will degrade the battery 5x less than charging to 100% – 5×80% – 400% compared to 1×100% =100%, if charging to 100% all the time. In laymans terms the battery will beable to be charged many more times and will last longer. Lithium batteries don’t degrade linear. The BMS slows the rate of charge at after 80% to prevent heat damaging the battery.
The i-miev had a range of 50 miles 80km’s, so getting 110km’s plus and 70km’s after 13yrs I personally find odd. Unless of course he isn’t telling us he had what was at the teme a common battery upgrade on his i-miev!!