AGM vs Flooded Bulk Times

BFL13 wrote:

I am wondering if the batts were really at 49% at the start, where that would be 49% of 220AH at the 20 hr rate, or well below 49% at the 20 hr rate. The initial draw down was at high amps so to know what the actual starting SOC was then, at the 20 hr rate, you would need the resting voltage to be that 12.2ish (no SG measurement with AGMs)

The clue might be the voltages reported once charging began at the 125 amps level. If you hit 220AH Wets at 49% SOC with 125 amps, the battery voltage will "spike" very high so that it will be close to Vabs 14.6 very quickly and amps will then taper right away. You are into absorption already.

I should have been more specific but the 12.25v was it resting voltage right before I hit the charger button. 12.25v is right in line with 50% SOC for Lifeline, but I definitely didn't do a 20hour rate. I took about two hours pulling them down to 108ah and letting them cool off and rest. They hit 105F on discharge and I started charging them at 86F.

BFL13 wrote:


Then 25 minutes of 125 amps to be 52AH so that would bring the batts to 108 + 52 = 160/220 = 73% SOC and not the 68% indicated.

(Unless the percentage accounts for heat loss????--which would make that : 68% = 149.6 - 108 = 41.6/52= 80 which would make heat loss 20% which is too high, but at 10% for heat that would be 46.8 + 108 = 154.8/220 = 70% getting closer! )

Or was the time at "125" partly less at first during the "ramp up?"

This is where I made a mistake I recorded amps from the charger rather than my shunt, I believe the shunt reading when at 125 amps was about 110 amps, the other 15 amps was 12v loads and losses.

The AGM1 setting on the Magnum is specifically for Lifelines with their recommended absorbs of 14.3 and float 13.3 at 77F.

I would like to try and to a 20 hour discharge test and be more specific on the voltages and amp readings.

Still not bad I put back 112ah in just over 2 hours, only a little longer than it took to get out.