Is NOCO Tech support completely wrong? Charging batteries in parallel with solar.

[Jdy328]

I just completed my first overland cargo trailer conversion build with a full 12v system and I think I was given incorrect advice from NOCO tech support.

I have (2) 100ah LifePO4 ran in parallel, connected to a distribution bar and out to a main fuse block. I contacted NOCO before the purchase and asked if I could connect the charger that the distribution bar (connected to two batteries) permanently and charge both without disconnecting anything at the same time... I was told it was not a problem. But it appears to be a problem...

So, I also have my 300 watt solar attached to that same distribution block (and an MPPT 110/30 charge controller). On my shake down trip this weekend I watched my Victron Charge monitor when I started and when I dropped to about 89% charge I turned on the solar (I have a breaker) and it had data on it but showed "0" watts on it and said it was shut off??? but within a few minutes (maybe 2) it showed 100% charge on the batteries and I know it didn't charge that fast. So I plugged in the NOCO charger and it blew a positive fuse (7.5) in line fuse. I shut off the solar and the NOCO and headed back after the trip was done.

I get home and I removed the batteries and replaced the fuse and it appears to work fine on a single battery.

I can not figure out if the NOCO will actually do what they said and I have no idea why my solar is off... I would love some advice.

 

[jonyjoe101]

The fuse would only blow if something was shorted, I would check to see if there is a wiring problem. Any DC charger / charge controller will have no problem charging 2 batteries in parallel. Once both 100ah 13 volt batteries are connected in parallel, they behave as one giant 200ah 13 volt battery. They will charge up and discharge with no problem.

Just make sure both batteries are the same voltage when connected together and also verified that the BMS hasn't activated in either battery. If the BMS is activated in one or both batteries that might give problems especially with solar, mostly voltage surges that might blow fuses.

As an example my 220ah lifepo4 battery is 2x110ah batteries connected together in parallel and been charging that way for the past 3 years, my 312ah li-ion batterybank is 12x 26ah batteries connected in parallel. I charge both with solar and they perform excellent connected in parallel.

As long as you don't have a wiring problem everything should work, the NOCO should be able to charge the batteries as long as it see's the batteries are at the proper voltage. It would be good idea to check each battery with a multimeter and see what they put out seperately, and also what the voltage is when connected together.

 

[NatersXJ6]

Do the batteries have individual onboard battery management systems? Do you have a diagram with wire sizes?