amberwolf wrote:BTW, to be more specific, to get the rough charger end voltage for 80% of the voltage of the battery, it's 80% of the difference in voltage between empty and full, added to the empty voltage.
However--if you want actual 80% of charge state, you have to know which cells are in the pack, then look at the actual cell specification sheet, which has a voltage-vs-state-of-charge chart. Then find 80% on that particular chart, and multiply by the number of series cells. Then use that for the charger's final voltage.
Just keep in mind that if you don't at least periodically charge to the full voltage, the BMS probably won't balance the cells. It won't matter if they're really good cells that are well-matched and used well within their specifications and not run down too far; if they stay balanced there's no worries. (but it would require manual checks to find that out).