Battery low voltage after sitting unused in cold?

[whomba]

Got the LiFePo4 300ah Wattcycle battery all hooked up in my off grid cabin back in late January. I then didn't return to my cabin till this weekend and I noticed my mppt controller was off.

I ended up unhooking the battery then reconnecting and that turned the controller on. Then, I noted the voltage was around 10.6v!(Verified with multimeter)

My best bet is that it was in a cabin with out heat and ambient temperature around low to mid 40s with minimal draw(whatever the inverter passively pulls) for a month and it just killed the voltage...? Is this normal or a signal of bad battery?

I've literally charged the battery once to top balance, and it is by itself, not joined with other batteries, installed it, and charged a chainsaw battery off it, then let it sit for 5 weeks in cold. Though it has been hooked up to the solar panels the entire time too...

Thoughts? An I doing something dumb here?

 

[fatjay]

I'm sorry to say, but 10.6v is considered dead.

I would verify what the inverter is pulling passively, if it's not being charged, over the course of a month it could drain the system.

If it dropped below zero while hte inverter is pulling power, that can be bad news as well.

 

[sunshine_eggo]

Got the LiFePo4 300ah Wattcycle battery all hooked up in my off grid cabin back in late January. I then didn't return to my cabin till this weekend and I noticed my mppt controller was off.

I ended up unhooking the battery then reconnecting and that turned the controller on. Then, I noted the voltage was around 10.6v!(Verified with multimeter)

My best bet is that it was in a cabin with out heat and ambient temperature around low to mid 40s with minimal draw(whatever the inverter passively pulls) for a month and it just killed the voltage...? Is this normal or a signal of bad battery?

I've literally charged the battery once to top balance, and it is by itself, not joined with other batteries, installed it, and charged a chainsaw battery off it, then let it sit for 5 weeks in cold. Though it has been hooked up to the solar panels the entire time too...

Thoughts? An I doing something dumb here?

If it got below freezing, your scenario sounds pretty likely.

LFP can discharge down to -20°C.
LFP can typically charge down to 0°C

If you were in between them, you could discharge but not charge.

Not sure what kind of inverter, but they burn juice even when loads aren't being powered.

Let's say your Inverter sips power at 10W. Your battery would be depleted in 16 days.

What controller?

 

[whomba]

Ya looking at historical data there was some below freezing days likely, maybe 3-4, then a bunch between 0c and 4.4c

I'm wondering if it dipped below, auto shut off went off then the battery "never turned back on"?

I did have to disconnect the battery and reconnect in order for it to even try to to power up my display which then pointed me to a low voltage warning ..

Rover 40a mppt
Renology 12v 3000w inverter

 

[seneysolar]

Ya looking at historical data there was some below freezing days likely, maybe 3-4, then a bunch between 0c and 4.4c

I'm wondering if it dipped below, auto shut off went off then the battery "never turned back on"?

I did have to disconnect the battery and reconnect in order for it to even try to to power up my display which then pointed me to a low voltage warning ..

Rover 40a mppt
Renology 12v 3000w inverter

Did you leave the inverter "ON"? If you did, that'll do it. Gotta shut it off when you leave.

I am all to familiar with the Renogy Rover mppt, they will not restart charging when the battery is drained. No matter how much sun you get. If batteries drain to the low voltage disconnect of the mppt, they will not reconnect without an external charger getting the battery side above 12.6 i believe is the magic number.

My advice is to shut inverter down when you leave and dump that Rover for a Victron.

 

[sunshine_eggo]

Did you leave the inverter "ON"? If you did, that'll do it. Gotta shut it off when you leave.

I am all to familiar with the Renogy Rover mppt, they will not restart charging when the battery is drained. No matter how much sun you get. If batteries drain to the low voltage disconnect of the mppt, they will not reconnect without an external charger getting the battery side above 12.6 i believe is the magic number.

My advice is to shut inverter down when you leave and dump that Rover for a Victron.

Victron will output absorption or float voltage to its terminals even if no battery is present. They're great for waking up LFP batteries in discharge protection mode.