I have been trying different charge profiles with the modified pm4b; one of which was an attempt to equalize a pair of 6v batteries. Both batteries have one bad cell with an sg reading of .010 below the others; and one of the batteries generally reads about .005 throughout, below the other. So, for example, while one might read 1.295, 1.295, 1.285, the other will read 1.290, 1.290, 1.280.
While attempting to equalize the 215Ah bank, I wanted to hold amperage at 11.5a, by adjusting the voltage up as necessary. And knowing my pm4b only goes into boost on near full batteries, I preset the voltage low to induce a soft start. Once it was up and running I adjusted the voltage to where it held at 11.5a. (I don't have my notes with me, but I think it was in the 16v range?).
EDIT: 11.5a were at 15.73v.
Once the pm did its 15 minute boost thing, voltage dropped, so I dialed it back up in an attempt to restore amperage to 11.5. This is when I discovered the pm4b's max setting is 15.42 Vabs. There has been a difference of 1.03v to 1.05v between boost voltage and abs voltage while charging, so I simply added 1.05v to that for its max boost voltage of 16.47.
EDIT: I have since seen it top out at 16.52v.
With the voltage now lower than it was, the amps naturally dropped to about 8 amps. But then I noticed the amps began to rise about an hour in to the charge. The last reading, after 5 hours of charge was 9.9 amps.
??? Is it normal for amps to rise during a 15.42v charge, with voltage being held steady???
The next morning I took some readings and saw little to no difference, so I did another similar charge for 3 hours.
??? The day after, sg readings were up slightly, the two bad cells were closer to their counterparts in sg readings, i.e; only .005 lower instead of .010, BUT the resting voltage of the bank had dropped from 12.81v to 12.72v??? Could this be a result of increased capacity after the high voltage charge?
I then charged the bank with my nautilus 15 amper, at 14.95 volts for a few hours, and the following morning, resting voltage was back up.
Any thoughts? thanks.
