BFL13 wrote:
noteven wrote:
... how long will the standard 7 way pin system take to recharge Li batteries?
Same time as "ordinary" batteries. ...
FLA batteries start to accept a charge and pull amps at 12.6V, but LFP batteries start that process at 13.6V, a whole volt higher. Depending on your alternator's voltage output and the voltage drop in your wiring, LFP could charge SLOWER than FLA, and FLP charging could fail to reach 100% SOC where-as FLA could.
With my 45A Progressive Dynamics Inc charger running in FLA mode, my old ~200Ah of FLA would pull 18A over 10ga wiring. Still running in FLA mode, my 200Ah of BB LFP at 30% SOC only pulls 4A over shorter and bigger 8ga wiring. Putting the charger into boost/LFP mode (boost the voltage) increases the pull to 39A. Point being, same charger, the LiFePO4 charge rate is 1/4th the flooded-acid rate.
Sterling (make of DC-to-DC alternator chargers) has some nice videos on YouTube where they wire LFP direct to an alternator with ~4ga wire, and the charging rate is pathetic. Then they insert a DC-to-DC charger in the line and the charge rate jumps substantially, because the charger can re-boost the voltage.
All in all, current is pulled based on volts being delivered. For 7-pin systems, the Achilles heel is voltage. Solve the voltage problem, and then you can start to worry about current problems.
--tg
