I buy Milwaukee and Ryobi power tools because they have Samsung Li batteries inside their battery packs.
If I am actively using them I will charge them up to 100% but I always run them down below the 75% level when I know the battery is going to sit overnight or longer.
I would like to apply your idea.
I only have 1 Milwaukee tool (I have yet to use) and no Ryobi's.
How do you know that it is at 75%?
Is there a monitor on the charger or do you know from experience on how to judge it?
In my humble opinion every lithium battery charger should have a switch on it to set 70% or 100% charge level.
On the Milwaukee M12 tool there are 4 LED for 100%, 75%, 50% and 25% on the tool itself, so you have to slide a battery in a tool to check it.
On the Ryobi tools the 4 LEDs are on the battery itself.
To make it easier for me I use a Kill-A-Watt meter on the charger and watch how many watt-hours goes in.
https://www.harborfreight.com/kill-a-watt-electric-monitor-93519.htmlThe Kill-A-Watt meter only reads down to 0.01 of a kilowatt-hour, or 10 watt-hours.
If I was to buy another I would get a competing meter that reads to 0.001 kilowatt -hours.
https://www.amazon.com/Suraielec-Ca...aWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVlHaving a timer to turn the charger off after so many minutes is a good idea - and could prevent a fire.
It was not too many years ago that one of Samsung’s cell phone lithium batteries was causing fires on airplanes.
