Whew! Man, I have BAD GAS!

drew4justice

Just curious if anyone can answer a question about the absorpbtion stage on my Tristar MPPT45.

I'm currently in absorption as I type this and my batteries are bubbling like an aquarium! We've had a streak of an hour's worth of sun, but I'm trying to bring a new bank of Trojan T105RE's up to proper specific gravity but we've have lots of clouds/rain around here. I don't expect the sun to last much longer.

MY question: If get 100 minutes of sun then the sky clouds over for 2 hours (so I never hit float) and then another 80 minutes of sun, would that cumulate and complete the absoption stage, or will it start over again expecting a full, non-stop charge of 180 minutes?

Assumptions:
--The absorption time configured on my MPPT is 180 minutes.
--I have my inverter off, therefore no load connected.


I guess I could wait and find out myself but it's interesting and educational getting everyone's feedback.

Drew

BB.

Re: Whew! Man, I have BAD GAS!

What is the charging voltage and what is the battery temperature (and do you have a remote battery temperature sensor for the controller).

You do not want to charge too high of voltage for too long... "Equalizing" a battery (charging ~15 volts) for long periods of time (over 30-60 minutes) is hard on a battery. Usually, you "Equalize" until all of the cells stop increasing specific gravity (back to back measurements every 30-60 minutes). And the usual plan is to equalize every 1-3 months--not every week or every day.

-Bill

drew4justice

Re: Whew! Man, I have BAD GAS!

Thank you for your input.

The temp outside is 73F. I don't think it's much warmer where the batteries are located since they're in the shed. I do however have a remote sensor installed on one of the (-) terminals in the middle of the bank. At any rate, the battery bank is about 4-5 feet below the mppt controller so the temp difference shouldn't be huge unless the batteries warm internally. They also feel fine to the touch.

I have 4 batts in series for a 24v bank. The charging (absorption) voltage is 29.4v. I'm not in EQ mode, just absorption. I'm a little concerned. Should they not gas in absorption? EQ for the T105RE's is 30.96 and my Trimetric as well as my Fluke meter show me at 29.4v. (Actually I made it sucessfully through the absorbtion and now I'm currenty in float at 26.4v with no more bubbling.)

EDIT: The S.G. is coming around just under the desired mark of 1.260. I have a cheap (read non-precise) hydrometer from Amazon, but I'm pleased to see the system bringing the S.G. up from around the 1.220 it was.

Drew

BB.

Re: Whew! Man, I have BAD GAS!

Sounds like everything is working well... You can adjust the voltages and timers to meet your needs.

I believe some folks here will set shorter absorb times in summer (lots of power) and longer times in winter (sun sets before charge controller times out).

-Bill