Please help, battery voltage reading

[jtjager]

Very confused why my battery shows a low voltage but soc shows 100% until a load is put on then jumps to 13.6 and about 10 min later drops back down to 13.1, and will jump back up when I turn on the fan in my camper which is 30 watts. I checked the battery terminals with a multimeter and reads the same. Epever 4125, lion energy battery. This all started happening after I disconnected the battery to change a USB port in the camper. Any help would be greatly appreciated

 

[sunshine_eggo]

Assuming BMV-7X2 or smartshunt.

Voltage and SoC for LFP have only a weak relationship.

The battery monitor works by counting amps in and out as well as considering temperature and load vs. rating to compute SoC.

If this occurs when solar is available, you likely need to look at your EPEVER settings. This sounds like a float voltage issue where the charger is allowing the battery to drift to a lower voltage, but when you apply a load, the voltage briefly drops to below some threshold, then the charger takes over providing the loads and raising the battery voltage.

Boost/bulk/absorption set to 13.8-14.4 depending on your preferences.
Float set to 13.6V
Re-boost or whatever EPEVER calls it, 13.2V

 

[MisterSandals]

Epever 4125, lion energy battery.

Is your Victron unit set to the correct battery type?

Has the battery (and shunt) been thru a complete charge/discharge/charge so that it learns your battery capacity?

Can you post a pic of your Victron settings?

 

[jtjager]

Changed the controller settings to the above suggestions, now the voltage is bouncing between 13.2 -14.6. Battery has been charged, should I disconnect the solar and drain the battery down then recharge ?.
Thank you so much for the advice

 

[sunshine_eggo]

Solar charging requires different settings for the battery monitior.

What are the EPEVER settings?

 

[jtjager]

Charge controller settings

 

[jtjager]

Now the panels display disconnected and the voltage is back at 13.1. Thanks for the advice, I am pulling my hair out

 

[sunshine_eggo]

Setup for sync on Victron BMV/Smartshunt:

This will only improve the accuracy of the battery monitor, not the voltage behavior.

If my theory is correct, it appears your SCC is not behaving consistently with its settings.

Using a voltmeter, I would check that all voltages are in agreement at rest, under load and during charge at:

1) Battery terminals
2) SCC output terminals

When you disconnected the battery, did you properly torque the connections when you resumed use?

 

[jtjager]

Thank you, I'll go over everything. Just can't see anything different than before I disconnected the battery.

 

[Bob B]

My first line of troubleshooting is to examine VERY closely what has changed. Was a poor connection or other problem somehow introduced when you did the USB port wiring?

 

[jtjager]

I've checked over everything, I just swapped out the USB port and didn't change anything else. I disconnected the panel and battery. Will hook everything back up tomorrow and see what happens.