question

asrick avatar image
asrick asked

MPPT 100/20 not fully charging batteries

I have 200watts of solar. On the sunniest day in Tucson it stays in bulk mode all day, only a few times has it ever floated. My batteries voltage is slowly falling. I am in an RV and on the road. I have been running the generator to get the voltage to 13.6. I have two new AGM group 31 batteries. My system is wired differently. I have no loads connected to the charge controller. I believe the loads are directly wired to batteries. I did not wire the system it was done by a previous owner. I have older Trace 2000 watt inverter. Everything works great other than the charge controller. It barely allows 1 amp to pass trough the charger and seldom uses 20 watts of solar, the norm is single digits. I am using the battery life algorithm. If I try to manually start an equalization it doesn't complete itself.

battery charging
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4 Answers
ben avatar image
ben answered ·

There are a lot of possibilities. Your panels could be an issue. You could have a wiring issue between them and your MPPT or between your MPPT and your battery. You might have a configuration issue in the MPPT.

It’s going to be hard to debug a whole setup over this Q&A forum, but you can start by getting your multimeter and measuring some DC voltages. Measure the voltage at the MPPT solar input when the battery is not full (should be charging) and the sun is out. Measure the output terminals of the MPPT. Measure the voltage at the battery. Turn on Victron Connect and see what voltage it thinks it is seeing.

Try to get all of those simultaneously or at least in stable weather so there is no fluctuation due to clouds.

Let us know what you find.

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Martijn Coster (Victron Energy Staff) avatar image
Martijn Coster (Victron Energy Staff) answered ·

Hi @ASRick

I think you should start by looking at your system in detail yourself.
How is the MPPT wired to the PV and to the battery. Check for any broken fuses.
How is the MPPT configured? Is it set to the correct battery voltage.

When not sure about the operation of the MPPT.
I would advise you to contact a Victron dealer to help you with this.
if you do not know who your dealer is, please visit: https://professional.victronenergy.com/support/

best regards
Martijn Coster - Victron Energy

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asrick avatar image
asrick answered ·

Thanks for the replies. I took some numbers.

Batts at mppt. 12.2v and charging

Solar input 13.3 to 13.6 fluctuating. Because of the mppt?

Load terminals at mppt 12.2v

Victron connect says 16 watts

PV is 13.16v. 1.2amps

Batts are 12.11v 1.3amps

Full sun but panels do not all get full sun at the same time because they are on a RV that has a rounded profile. 100watts each side. The panel voltage is over 19watts. I have 2 Duracell 105AH agm Batts, 2 months old now. I have to use the Gen to top them off with the RV charger everyday. I'm on the road with bad cell service most of the time. I should have service for several days now.


Thanks,. Rick

.

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asrick avatar image
asrick answered ·

Whoops, the solar panels produce 19 volts or better. The battery leads are connected to+ and - as are the pv. It's got me puzzeled. Perhaps my controller is defective? I've had some poor solar days, but I've also had some very good days. Charging results are not good on the good days. My Gen is running as I type ,today was not a good solar day here. It clouded up by 12:30. I have sun now but know from experience not enough to get me charged. Any suggestions are welcome. Thanks

Rick

1 comment
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What brand/model of panel?

Are they 32 cell panels?

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