75/10 Bluetooth MPPT showing voltages but not charging

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manjusri52 asked May 13, '20

75/10 Bluetooth MPPT showing voltages but not charging

I have the 75/10 MPPT hooked up to a 12V VRLA gel battery and a Renogy 100W PV panel. Basically the same setup as I have in my van, which works great.

For some reason, this setup doesn't want to charge the battery. It's showing what looks like correct PV and battery voltage, but no current or PV production.

Occasionally, the LED on the charge controller will show a solid blue light and the PV voltage will fluctuate, but there is still no current. The battery status will show "bulk" on the app. I confirmed there no current with a multimeter. See below:

But most often, the battery says "off" on the app, and the PV voltage matches the battery voltage. I've tried disconnecting and reconnecting, disconnecting and leaving off for hours before reconnecting, and nothing seems to make it want to charge... see below:

Any advice?

MPPT Controllers battery charging mppt charging

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Answer 1 · 2020-05-13T06:37:01Z

ejrossouw answered · May 13, 2020 at 06:37 AM

Hi @manjusri52 The charge controller will only get going at bat V +5 and you are at least 3V short of it. What is the setup in the VAN? PWM maybe or more panels?

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Answer 2 · 2020-05-13T06:53:24Z

manjusri52 answered · May 13, 2020 at 06:53 AM

Hmmm that would make a lot of sense. I have a large panel on the van. It’s an REC-285. VoC is like 45V. So it seems my panel is too low-voltage. Is there any Victron controller that will work with this PV panel? There must be a way to charge a 12V battery with it?

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ejrossouw commented · May 13, 2020 at 03:57 PM

Typically a PWM charger should get over this limitation. You will find some options here.

https://www.victronenergy.com/solar-charge-controllers/bluesolar-pwm

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