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Al avatar image
Al asked

Solar Panel Dead - Can I use an AC/DC adapter to pretend to be a solar panel?

I have a Victron Energy Smart Solar charge unit configured to charge a LiFePO4 battery. I don't have a lithium battery charger!

My solar panel is dead. :(

Can I connect in a AC/DC adapter with an output of 12V / 5A into the PV input of my charge controller as power to charge the battery or is that a ridiculous idea? From my terrible physics makes me think that would equate to 60 watts which is enough to slowly charge a 100Ah battery.

I need to charge the battery before I can get a new panel as I need to spend a night off gird on my van this weekend. Lights would be nice... :)

pxl-20230927-185025659.jpg


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3 Answers
Kevin Windrem avatar image
Kevin Windrem answered ·

Maybe but you need a voltage that is 5 volts above your battery voltage.

The MPPT may also overload the AC/DC adapter. That might be OK of the adapter current limits but if it shuts down on overload then it would not work at all.

An inexpensive battery charger is a better approach. Just make sure it can be set for your battery type — LFP in the case.

If you still have the converter in your power panel connected, then turning it back on will also work to charge your battery to a usable state and power your lights. The battery may not reach 100% SOC however If it can’t be set to LFP.

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Al avatar image
Al answered ·

I used a 20v 4.5A AC/DC adapter. It didn't work.. the power went up and charged for a second, then down again then up then down repeatedly. Oh well.

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Rusty's Gaming avatar image
Rusty's Gaming answered ·

I have done this before it works, Yes the ac/dc adapter will work. You need to lower the solar chargers output to lower amps.

example a 75/15 controller outputs 15 amps, lower this to 6 amps and it will work.

adapter, 20v x 4.5a = 90 watts

battery, 90 watts / 14v = 6.4amps

I would lower output to 5 amps to keep the adapter from getting to hot.

It will take along time charge but it will charge.


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