My Screwy 31

landyacht318 wrote:
I wound up taking ~60 A/H from the 31 last night, and the lowest voltage recorded by sunrise was 12.0x when the compressor fridge cycles on with the fan load about 3.5 amps total.

The night before, it was hitting 11.8x under the same general depletion and max loads. Even the incomplete eq cycle restored voltage to younger battery expectations.

Just before noon today, and 32A/h from full, taking 9.2 amps at 13.7v, I allowed it to see alternator current. Took 37 amps + 9.5 solar amps to bring voltage upto 14.9, and tapered to 22amps by the time I parked in front of ocean 5 minutes later, where I separated the AGm and 31 after I shut down engine. 9.5 solar amps had 31 at 14.1v.
Alternator not able to hold 31 at 14.9v at idle speed en route. Dang traffic lights.

No alternator current on return trip as it was already in ABSV mode when I rinsed off the salt water at 2pm. Starting engine during ABSV mode triggered 15.3v float mode, even though 31 was not hooked to alternator, drops back to 14.9ABSV with engine off.

After a few errands, and back home, I Released the solar 15v max hold I had on the 31 switched loads to AGM27, and 6.2 amps were required to raise 31 to 16v.

1.270, 1.275, 1.280

30 minutes later, 4.1 amps

1.285, 1.285 , 1.290
End EQ.

So nice having flooded battery at easy eye level. Pop hood, pop cap, dip hydrometer, turn manual switch, change solar voltages......
wait a minute, thats a lot of steps!

Cycling AGM tonight, as it was already 12ah in the hole come sundown.

I'd say perhaps a few minutes more at 16.0V, with this being summer, will it bring all the cells up to 1.290? Your battery is being worked hard, cycled deep, and being treated well on the recharge cycles.

Almost kind of wonder what difference would be if you went to 15.0 instead of 14.9 on solar in bulk mode, daily? Would it keep the SG up a little longer and require less EQ charging once every 2 weeks or so?

While I don't use my T-1275 at the level that you use your 31... for me, daily bulk at 15.0V is what she sees, but I am charging at only 6. 5A from a portable 120w solar panel, not as many beans as your outfit, so perhaps the slight voltage increase at lesser amps is what makes it work for me. The function of really getting a top charge, daily, to me, seems to be what is healthiest for the battery.

I also believe in summer heat to keep the water topped off in the cells to lower the SG and acidity a bit due to the heat, and let it drop a bit come fall into winter, to raise the SG and the chemical reactivity differential in cooler weather, between plates and battery acid.