diy solar

diy solar

I have to set controller to 18V to get full charging current to 12V BB batts. Why?

cottersay

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Joined
Aug 11, 2021
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When using my 60A PWM solar charge controller (model BSC6048) on the “LiFePO4: 3.2V-4S” setting versus the controller’s other LiFePO4 setting of “3.2V-5S”, I only get half the charging current (10A) to my two parallel BB 12V batteries with my 4 x 100W parallel connected solar panels. In other words, only when I increase the Constant Charge Voltage setting of the controller from 14.4V (default for the 3.2V-4S setting) to 18V (default for the 3.2V-5S setting) does the controller/panels output their full and expected 20A charging current to the BB batteries.

So, my concern is this: is 18V CCV safe for the two BB batteries? Is this "normal"? Why not full charging current when CCV set to 14.4V?

Thank you!

-Cotter W. Sayre
 
What voltage are your panels and how are they wired?
 
BB has more than one meaning on this forum .... are these Battleborn batteries?

The most likely problem is voltage drop between your charge controller and the batteries. You would need to check the actual voltage with a DVM at the charge controller terminals and compare that to the actual voltage reading where they connect to the batteries. ..... when you have it set for 14.4 V
 
Thanks Bob, you hit the nail on the head: I had a Chinese SAE sex changer in the 10 AWG line, and it had so much resistance that it was melting. (I had touched it and it actually burnt my hand.) So, I thought I might as well go whole hog and I took the solar controller from its waterproof RV pass-through and placed it a foot away from the Battle Born batteries. So now instead of using 30 feet of 10 AWG cable, I now have 2 feet. I'm good to go!
 
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