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Dosheimer avatar image
Dosheimer asked

MPPT 100/50 over voltage 15V?

Hi!
I have a MPPT 50/100 in my 12V system (4x100AH AGM batteries parallel and 4x100WP solar panels parallel) and I did the setting at the MPPT 50/100 to AGM spiral cells at 14.7max. charge voltage. The correct setting is shown in the bluetooth app also. Nevertheless the charge current goes up to 15V for a few seconds and then back to 14.7 and 14.8V when the batteries are nearly full. The 15V are shown in the Victron app and this is also what I see on my multimeter measuring directly at the battery.
My concern is that this is destroying my new AGM batteries? What could be wrong?
Hope you can help me!

MPPT Controllers
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Alexandra avatar image Alexandra ♦ commented ·

If it is not sustaining the higher voltage then no damage should happen. Is there any gas venting from the batteries?

It is possible the higher voltage for thise seconds is an interaction between the mppt and the way the battery is responding to the charge being received near full charge. But if the mppt is not keeping it there and the batteries are not heating up or venting gas then there should not be a problem.

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Stefanie (Victron Energy Staff) avatar image
Stefanie (Victron Energy Staff) answered ·

Hi @Dosheimer,

maybe temperature compensation?
You may check what temperature compensation is set to in the VC app and compare to ambient temperature.

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Dosheimer avatar image
Dosheimer answered ·

Hi Stefanie,

Thanks for your info, but I disabled the temperature compensation before.
Even if enabled: As far as I know the temperature compensation is 16.2 mV/°C counted from 25°C.
I have had an ambient temperature of around 14°C. Tis would mean: 11 x 0,016V = 0,0176V compensation (please correct me if I am wrong).

My difference between 15V and 14.7V is 0,3V

Therefore this might not be a valid reason for the overvoltage. Hope someone can help me.

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Stefanie (Victron Energy Staff) avatar image Stefanie (Victron Energy Staff) ♦♦ commented ·

11 x 0,0162 = 0,1782V - that's roughly 0.2V

Anyway, since you had compensation disabled, that should not be the cause. Hope someone else can help further.

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Elimac avatar image
Elimac answered ·

What about the loads? Are you switching off any important loads at same time you observe the voltage rise? If so, it will be normal.

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njms17000 avatar image
njms17000 answered ·

Hello , i have same problem , but in my case , solar controllers showing alarm 38 and some times 40, my battery system is 6 x 400ah 12v.

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Nick avatar image
Nick answered ·

I'm no expert here, BUT you have a bank of 4, are you sure one of them doesn't have a faulty cell or need an equalization charge/ have sulfation? I would be looking to test each battery individually and see how it responds to a dedicated charge.

What brand of batteries and did you follow the manufacturer spec for Absorption and Float? Remember you can select the AGM Spiral preset as a profile and then adjust the Abs/Float voltages to your specific battery requirements. Is equilization set to Manual?

Also how did you wire these when you put them in parallel, Page 18/19 of Victron Wiring Unlimited just to double check.

parallel.png


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