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miltonreg avatar image
miltonreg asked

Connect a DC Battery Charger in Parallel with a PV on a SmartSolar MPPT 100/20 Charge Controller

Hi,

I have a configuration of a SmartSolar MPPT 100/20 with a 120W PV and a 100Ah battery (all 12V). It works nicely, however, I would like to know if it's possible to connect a DC Battery charger in parallel to the PV so it can charge the battery when there's no sunshine, like on cloudy/rainy days.


I've done this before with some PMV controllers, using a 12V 8.3A 120W DC charger, a but I'm not sure if it works with MPPT controllers.


This configuration would be used to power-up some communication devices installed on a pole, which even though it has one day of backup power, sometimes it's not enough during prolonged cloudy periods.

Thanks in advance for your help.

MPPT Controllers
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2 Answers
Rob Fijn avatar image
Rob Fijn answered ·

Hello @miltonreg, Yes this will work. But you need to tweak the charge voltage a bit. Otherwise the MPPT will not charge as it believes the battery is full because the DC charger is keeping up the voltage. I have been playing with it too. But did not come to the point to change the voltages, as I just switch the DC charges ON when needed in the night.

Regards, Rob

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miltonreg avatar image miltonreg commented ·

Great!

I made a mistake posting my question. The DC charger's output is 14.4v @8.3 Amp. so I think it will work.

Thanks.

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launacorp avatar image
launacorp answered ·

I had a similar setup from the theory. I had a Power Adapter which has a self made relais box on the mains voltage side. If the Vbatt is okay, the load output of the MPPT powers the Relais and cuts the mains voltage from the Power adapter. If the Vbatt is low, the load output profile of the mppt disables the load output, then the Relais fall off and the power adapter turns on, so all is running on mains power and the PV can charge the battery.


Just some idea what you can do...

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