Re: Always check your contractors' work

Scott SV Tengah

I learned this through monitoring my batteries. 

The electrician connected the positive lead from the MPPT to the positive post of ONE of the batteries. His thought was that it would be like a bunch of interconnected cups. Once this first battery one got some charge, it would overflow the current into the next battery and so forth. I am no electrician so it sort of made sense at the time.

Well, monitoring showed me that this does not actually occur. The Battery1 that was directly connected to the MPPT was always higher voltage than the rest. The further away from the MPPT-Battery1 connection, the lower the voltage. The entire bank was being actively imbalanced!

Now I have the positive attached to the post where all the battery positives join. The batteries have remained balanced over the past year.

I can't remember where I read it, but a marine electrician stated that "in case it wasn't obvious, you connect the MPPT output to the load." I don't quite have it perfect as it's where all the batteries join, but I'm going to relocate the MPPT anyways, so I'll connect it to the load then.

Sorry, if my explanation isn't precise enough as I never studied engineering. Just lots of reading, lots of testing and lots of monitoring.

2007 A54 #69
SV Tengah

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