Maximizing battery life

This is an astounding graph for those who haven't seen it. Lithium Ion batteries were over $1,100 / kWH storage in 2010, just 9 years ago. They are now down to $156 / kWH storage, a massive drop. This is why the Prius was appropriate tech for 2010, and we have EV's like the Niro now...

 

I also have all electric lawn tools. Have had then since 2017. almost 3 years. These are the Kobalt series lawn mower and weed trimmer.

They are powered by 80 amp 3 ah lithium batteries,they came with batteries as a promotion.I actually have 5 of these lithium batteries. I numbered them so I can keep track of them. These batteries are without exception run until they are completely exhausted. Then put on a charger until the are 100% charged and left on the chargers until needed again.

Unfortunately last November I left two of these batteries on their chargers plugged in until April when I again need them. The effect on these two batteries was-- none. Both batteries performed and charged up just as well as the other 3. In the almost 3 years we have owned them after countless discharge cycles to 0 power and recharge cycles to 100% the net effect on their performance and life is --none. I should add the batteries and chargers are housed in an attached garage where temperatures reach in excess of 100 degrees in the summer and down to 0 degrees in the winter.

My experience with this technology both in cars and in lawn tools is positive. Perhaps the most positive is the lack of attention and care these products take. It makes them much more convenient to the consumer than gas appliances and cars. If it was inconvenient or required more attention then it is a step backwards not forwards!

 

Older Priuses made use of the NiMH batteries by cycling between 40 and 60% according to one of those links I posted earlier, leaving extra capacity for "overcharging" on downhills and probably vastly increasing cycle life by not deep cycling. I do not know what their LiION battery management is.

Note that the 100k guarantee is likely written to be bullet proof with someone who fast charges continuously to reach 100k miles before seeing degradation to 70%. I trust with some care on cycling the pack will last MUCH longer before degrading that far. THAT is my goal. It is not resale value that concerns me as much as getting the most out of the carbon investment that went into producing the battery pack. I am hoping the car is falling apart before the battery pack becomes unusable.

It is fortunate you have not seen the lawn tool batteries die, however, invisible to you is any built in battery management. Even something as simple as the charger shutting off charging once current drops below a certain level and not turning it back on until the battery has been removed and a new one inserted turns the accidental experiment into storing it at 100% charge for several months. Not a great idea, but not all that damaging either.

Until you cycle the each battery at least 500 times, and more like 1000, you will not see noticeable degradation from a "how long can I use my hedge clippers" perspective. I have a rechargeable screen shaver. I have had the former for probably at least 7-8 years...but I only need to charge it once every couple of months so I suspect the shaver has only cycled ~50 times. Their batteries seem fine, too, but that does not mean much.

 

I think you are exactly right -"It is fortunate you have not seen the lawn tool batteries die, however, invisible to you is any built in battery management. Even something as simple as the charger shutting off charging once current drops below a certain level and not turning it back on until the battery has been removed and a new one inserted turns the accidental experiment into storing it at 100% charge for several months. Not a great idea, but not all that damaging either." Battery management and engineering is a wonderful thing. It helps take the human element out of the equation when you forget to unplug the chargers for the winter ( I remembered this year to unplug the chargers) or charge under less than ideal conditions.