question

peterpan1 avatar image
peterpan1 asked

Can I charge a battery with a Victron MPPT 75|15 by simply supplying it 17 V DC from a bench power supply instead of connecting it to solar panels?

I only use my solar system during summer and I'd like to top my batteries off-season with a cheap method. I do not want to invest into another battery charger, so I figured maybe I could simply use the MPPT for this purpose.

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2 Answers
Justin Cook - Bay Marine Supply USA avatar image
Justin Cook - Bay Marine Supply USA answered ·

@peterpan1, it's worth noting that since the MPPT needs battery voltage +5v to initialize, you'll probably want to run your power supply at a minimum of 18v to make sure the MPPT turns on... 17v will only turn it on if your batteries are at <12v, which obviously is well below where they'll likely be sitting.

Otherwise, yes, this definitely works... I use a variable power supply on my test bench to test MPPTs, though I'm usually running at around 22-24v just for the sake of ease. For a 75/15, your only critical consideration is making sure you don't exceed 75vDC in, which shouldn't be a problem.

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Paul B avatar image
Paul B answered ·

Yes you can do this,

make sure that the charger can supply a continuous rated 15 amps or you may damage the charger if the batteries are flat etc.

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sean avatar image sean commented ·

The bench power supply doesnt need to be capable of continuous operation at 15A.

It simply needs to be capable of continious operation at its maximum rating, whatever that is - likely less than 15A.

The MPPT will simply maximise the amount of current available from the source.

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