Lifepo4 battery goes from Float to zero volts overnight.

[mr.palmer]

I have 4 pv panels in series connected to victron 150 | 85 mppt smartsolar controller. And charging a 12.8v voltx 200Ah lifepo4 battery. My problem is that even after the victron connect app shows the battery has gone through bulk, absorption and float stages it goes flat overnight with minimal output. This has happened multiple times. I'm using the victron lifepo4 settings on the controller. Now this morning, same issue again but once the sun hits panels and charge flows I also get an error code for over heating. The battery neg cable on the controller got really hot. I have turned off the whole system. Any thoughts.

 

[sunshine_eggo]

Please post VC home screen and include "last 30 days" and "Detailed" views.





Triple check that all connections are properly torqued and are of high quality with good crimps and no shrink pinched or washers in the current path.

You must you fine strand wire at the MPPT terminals.

 

[chrisski]

Can you send a picture of the battery negative cable?

 

[mr.palmer]

Yep, wrong cables from solar controller to battery. But would that result in these voltage drop outs? What cables do you recommend between victron 150|85 and battery? Is 2awg excessive?

 

[pollenface]

Perhaps there is an imbalance that is causing bms disconnect.

 

[Hedges]

Yep, wrong cables from solar controller to battery. But would that result in these voltage drop outs? What cables do you recommend between victron 150|85 and battery? Is 2awg excessive?

Only at high current. Although the heating might have affected some reading.

I also get an error code for over heating. The battery neg cable on the controller got really hot.

So the heat reached something that measured it.

The fatter the better. 2 awg is good for about 130A. Maybe more than is actually required.

My problem is that even after the victron connect app shows the battery has gone through bulk, absorption and float stages it goes flat overnight with minimal output.

"Flat" meaning BMS disconnects for low voltage? Something else?

My first thought was your charge voltage wasn't high enough to actually fully charge that battery, but you did say LiFePO4 settings.

The particular high and low voltage limits will matter - the other guys here have experience with such batteries and SCC. I don't, can only look at tables and curves.

 

[Q-Dog]

I have 4 pv panels in series connected to victron 150 | 85 mppt smartsolar controller. And charging a 12.8v voltx 200Ah lifepo4 battery. My problem is that even after the victron connect app shows the battery has gone through bulk, absorption and float stages it goes flat overnight with minimal output. This has happened multiple times. I'm using the victron lifepo4 settings on the controller. Now this morning, same issue again but once the sun hits panels and charge flows I also get an error code for over heating. The battery neg cable on the controller got really hot. I have turned off the whole system. Any thoughts.

What do you consider "minimum output?" How much power are you using? I see 8 or 9 times the battery has gone below 10 volts ... so either run empty or the BMS disconnected.

 

[AntronX]

The battery neg cable on the controller got really hot. I have turned off the whole system. Any thoughts.

Use fine strand welding cable. Those battery terminal blocks Victron uses require fine strand cable or it will overheat and melt. Set your absorption and float voltage to 13.6V to make sure unbalanced cells don't trip the BMS prematurely.

 

[mr.palmer]

What do you consider "minimum output?" How much power are you using? I see 8 or 9 times the battery has gone below 10 volts ... so either run empty or the BMS disconnected.

A 12v bushman fridge averages 1 amp per hour. A couple of led lights for a few hours . Minimal load.

 

[mr.palmer]

What do you consider "minimum output?" How much power are you using? I see 8 or 9 times the battery has gone below 10 volts ... so either run empty or the BMS disconnected.

A small bushman 12v fridge, average 1 amp per hour. A couple of led lights for a few hours.