It due to tech how those are charged. Charging is stopped when amperage is near zero. That's what charger detects. When removed, voltage in battery will drop slightly, something like 0.1 volt or similar. When put back, charger will detect difference in voltage and there will be enough current to start charging again. I dont recommend this since it will probably decrease battery life somewhat.
Ahh, interesting thanks. I thought they worked on a Delta V system.
I believe that method is for those smaller batteries like AA and AAA with NiCD i NiMh chemistry.
Having trawled Google Scholar, because it’s years since I learnt Li tech. On a bog standard li charger. When the battery reaches a certain voltage level the ingoing current drops, this is used to indicate the battery is charged. That sounds awfully like Delta V. So maybe it’s just the term that’s fallen out of use.
Im not an expert by any means, just like to be informed, particularly regarding the safety. What i do recommend on general battery info to check: https://batteryuniversity.com/
In short, if you charge battery to 4.1 instead of 4.2 volts it should almost double it life. The more you gravitate around 3.7v the less battery will be stressed and live longer. Of course that way you get less battery capacity per cycle. Personally, i charge batteries up to declared 4.2v and dont think about it too much.
