LFP battery discharging with converter on

[chriscowles]

First time out with new LFP batteries. To recap the system, in addition to switching to LFP, I added a 4 AWG welding cable parallel to the OEM 8 AWG wire between the battery and the converter. I did not upgrade the OEM WF-8955 power center because I have a solar system to top off the batteries.

I have a QWork shunt battery monitor. It seems to work, measuring SOC accurately. Having tested by adding small loads and cycling the SCC on and off, it also appears to show charge direction and quantity directly. I compared SCC output to the battery monitor and it was close.

My problem is that it shows a small discharge under normal operating conditions when the converter is on and the battery is connected. The only thing running is a few lights, the refrigerator on gas, and the Fantastic fan on medium.

If I disconnect the battery, everything works normally, so the converter supplies the trailer as it should. Also, the battery monitor reverses to positive flow from the SCC.

Yes, it's a WFCO, but why does the converter not supply the battery with a positive charge when connected, even if small? Is the LFP battery voltage (100% full) too high for the converter to supply power?

[CivEngPE]

The problem, I believe, is that the LiFePO4 battery is a higher voltage than the converter. After a few hours, the WFCO converter drops down the voltage. The float voltage on the WFCO is just 13.2V while the resting voltage of the battery is 13.6V.

[CHICKDOE]

As stated above and/or the solar is providing a higher voltage than the converter is providing. Power is flowing from these higher voltage devices.

[chriscowles]

Originally Posted by CivEngPE

The problem, I believe, is that the LiFePO4 battery is a higher voltage than the converter. ...

Originally Posted by CHICKDOE

As stated above and/or the solar is providing a higher voltage than the converter is providing. ...

Thank you for your insights. I interpret that as being harmless and I can ignore it. If I'm wrong, let me know.

If I'm ever boondocking in bad weather I'll run the generator to recharge the batteries. The voltage will be low enough to allow the converter to go into bulk charge as expected.

[CHICKDOE]

It will recharge the batteries to some level but won’t fully charge them as you are relying on the solar to do that. But it will get you by until the sun comes out.

[chriscowles]

That's what I'm planning on. I have enough Ah (200 usable) that 80% is plenty. As LFP is not damaged by undercharging, as FLA is, I'm not worried about it. I was just kinda baffled by the batteries discharging with the converter on.

Thanks