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cody-shreve avatar image
cody-shreve asked

Victron mppt 75/10 on rv

Hello, I have the MPPT 75/10 Victron solar charger. When I shoot voltage straight from my 100wpanel I am getting 20volts. When those wires are connected to controller it drops and caps at 12volts according to the app and multimeter. It never goes above 12volts. How can I fix this so the solar controller will charge my 12v battery

MPPT Controllers
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simon-ytterbom avatar image
simon-ytterbom answered ·

@Cody Shreve

When you put a load on your solar panel, the voltage will drop (this is normal). For it to go from 20V to 12V sounds like a lot. I would check the wiring as well to make sure you do not have a loose connection at the MPPT terminal that is causing the voltage to drop. If you connect the Panel to the MPPT, you can check in the Victron Connect App (if the MPPT is smart) and see what the voltage is at the MPPT. If it is 12V at the MPPT, you may have a voltage drop in-between the Panel and the MPPT causing this. Best option is to use a voltmeter at each connection point to see where you lose the voltage.

You can also disable the MPPT charger in settings. This way, the MPPT should be reading close to OCV (and therefore close to the 20V you read directly at the panel).

Below is a link to a nice video about this that can be helpful.

One solution would be to add a second panel in series to increase voltage.
https://www.youtube.com/watch?v=uTMVmW7GTus

Thanks


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cody-shreve avatar image cody-shreve commented ·
When shooting voltage from panel I am shooting it from the end of wiring that connects to MPPT. So not directly from panel. 20volts when disconnected and then I shoot at MPPT terminals and get 12Volts when connected again.


To me it may be my settings could be messed up but not sure. Wiring seems ok leading up to solar panel as I am getting 20 volts however connecting those wires I shot 12 volts and it never goes above that in full sunlight

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nickdb avatar image nickdb ♦♦ cody-shreve commented ·
There is no load, any issues (loss) would become apparent with load.

Either wiring is off or your panel is insufficient.

Are your battery settings right? You can share a screenshot.

More often than not this tends to be wiring.

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cody-shreve avatar image cody-shreve nickdb ♦♦ commented ·

Battery is a 12v agm

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082229ba-4c6b-4d85-b9e0-3367f7930edc.png (376.8 KiB)
cody-shreve avatar image cody-shreve nickdb ♦♦ commented ·
What would I need to do to make sure my wiring is ok or not? Should I replace all the wire with bigger wire?
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nickdb avatar image nickdb ♦♦ cody-shreve commented ·
What gauge and type are you using? How long is the run?

Check any connectors and lugs/crimps.

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cody-shreve avatar image cody-shreve nickdb ♦♦ commented ·
Not sure on gauge. Run is probably around 10-15 feet I would guess
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cody-shreve avatar image cody-shreve nickdb ♦♦ commented ·
Top/front of camper to storage area on left side of camper
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cody-shreve avatar image cody-shreve nickdb ♦♦ commented ·
10 gauge wiring. It does say low voltage but that should be fine?
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cody-shreve avatar image cody-shreve nickdb ♦♦ commented ·

Here is my history since installing yesterday. I guess it produced power yesterday. 45Watts and 20volts

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cody-shreve avatar image cody-shreve commented ·
Also if I disable charging, the MPPT won’t charge my battery. If it jumps up to 20volts when off, is that a flag that my MPPT is bad?
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simon-ytterbom avatar image simon-ytterbom cody-shreve commented ·
Most likley not a bad MPPT but something with the wiring or a bad panel.

Difficult to say. I would contact your distributor to get someone on the phone to chat about it.
Turning the MPPT off was to ensure that you see the same voltage on the panel as the MPPT sees. But for it to drop that much, a bad connection or panel issue is most likley the case.

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