I have a Victron charge controller 75 15 and two Battleborn lithium 100 amp hr batteries. Two days ago I was able to get the batteries to a full charge of 14.2 both readings by smart shunt 500a and meter to the batteries. Life was good. Now as of this morning the batteries are reading 12.70 both by smart shunt 500a and meter to the batteries. The smart shunt 500a is still showing the batteries are at 100%. Only item pulling power on the batteries is the smart shunt. Please advise if you can. Also per the Victron board I did make some minor adjustments to the smart shunt and the controller
You most likely have a drain that’s bypassing the shunt, usually a chassis ground cable or other negative that’s connected straight to the battery, or to the wrong side of the shunt, rather than to the Loads side of the shunt. Post some photos or a diagram of the setup and we can most likely help from there.
Also note that 14.2 isn’t fully charged on Battle Borns, you’ll need to be charging to 14.4 so that their internal cell balancing circuit can activate. 14.2v is the correct setting for Victron LFP baatteries, but Battle Borns need 14.4
As Justin said, having an unmeasured draw is one possibility. The other is early synchronisation to 100%. See the FAQ page, topics 2 and 3 cover these if you have not seen them, you say you have already taken some advice.
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Thank you for the information. At times I think I’m in over my head with all this. Learning. Taking all the advice I can get.