MPPT controller and a AC 12V battery charger at the same time?

[glenkleidon]

I saw a youtube video where Will Prowse said it was ok to run multiple charge controllers on the same battery bank. I wonder if it is true that you could run a mppt controller AND a 12V Auto battery charger on the same battery at the same time? My main concern is to avoid damaging either charger controller or the charger (or the battery for that matter). I have it wired up now, but too scared to turn it on....

 

[Rednecktek]

I do it every time I head to my camp. Since I disconnect my entire system from the batteries when I leave they tend to have dropped a bit by the time I turn the MPPT back on, so I've got a "Smart" charger capable of doing 25a charging and I just kick it on once the generator is fired up to top up the batteries.

Yes, my current solar (200w) is very undersized for my battery bank (4p FLA 120Ah) so I'd need the charger anyways just due to not having enough panel...

Yet... Muwahahaha!!

 

[glenkleidon]

OK, worked up the courage. Turned on the auto charger and its charging ok. It is a micro-controller driven one though - so I expect it is sampling the voltage thousands of times per second - so all should be good. Mppt controller does not seem to care. There is no wind blowing either so the (hybrid) wind/solar charger isnt doing anything anyway. Interestingly they don't agree about what the batter voltage is though!

 

[Rednecktek]

Interestingly they don't agree about what the batter voltage is though!

Not surprising at all, but they should be close. You can always poke it with a meter and figure out which one is lying more, but they say if you put 4 meters on a battery you'll get 6 voltages.