Peter Tourin
2020 Unity RL, ex 2012 Unity MB
I got some info from Progresive Dynamics today. Their lith chargers charge at their rated current until the battery is nearly fully charged, then they hold 14.6 volts and the supplied current drops as the battery voltage climbs, until the charger is basically delivering no current. The charger does NOT switch off when the current drops below a preset point. I'm trying to figure out what this implies - it seems that once the battery is charged, the charger acts sort of like a float charger - as the battery goes down a bit, the charger starts supplying current (but always at 14.6v).
I'm no engineer, and I'm not sure whether the batteries mind being treated this way. I don't think the charger can overcharge the batteries - if there's no voltage differential I don't think the charger will supply any current. But I have a memory of reading a white paper indicating that it might not be good to keep pushing li-po batteries right up to full charge. Once I have the new charger in place and watch it for awhile, I could handle that - the Victron monitor has a set of relay contacts that can be made to close at a preset high voltage and open at a lower voltage - I could use that relay to feed a 2nd relay that opens the 120vac to the charger. More complexity and current drain of course. But not hard to do.
I'm no engineer, and I'm not sure whether the batteries mind being treated this way. I don't think the charger can overcharge the batteries - if there's no voltage differential I don't think the charger will supply any current. But I have a memory of reading a white paper indicating that it might not be good to keep pushing li-po batteries right up to full charge. Once I have the new charger in place and watch it for awhile, I could handle that - the Victron monitor has a set of relay contacts that can be made to close at a preset high voltage and open at a lower voltage - I could use that relay to feed a 2nd relay that opens the 120vac to the charger. More complexity and current drain of course. But not hard to do.