We had a freeze recently. This is our first freeze with our setups.
We use SOK lifepo4 batteries.
We had one setup go to 0% SOC and the batteries turned themselves OFF
They will “wake” back up if 24V is applied to them…
I was under the impression that the Victron MPPT controller can wake up a sleeping BMS, but they didn’t.
This was once the freeze was done and we had blaring sunny days.
When I put a voltmeter to the “battery” terminal of the MPPT, with full sun, it was only like 2V… (it should be 24+ volt).
I had to apply 24V using a makeshift portable charger to wake them back up and have the MPPT start charging them again at the correct 24+v
Is there some setting I have wrong? I could have sworn that the MPPT wil push out 24+v even with the battery unhooked with full sun.
I read somewhere also in literature that victron mppt can wake up a depleted BMS…
You aren’t making that up. I have heard similar things but also have never had that experience or had any of my clients have that experience with my installations. I have LOTS of Victron MPPTs installed out there in RVs with LFP batteries. Every year a couple people forget their fridge is on in storage or something and put their LFP to sleep. It always requires a forced charge to wake them up. I have never had the MPPT do it on its own.
They can wake up a depleted battery. We use the for black starting offgrid sites.
That being said, not all BMS will allow it. At 0% the manufacturer may prefer a person actually attend in case there is a problem.
The second issue is the temperature you are referring to. That could also possibly be why the batteries (and mppts) did not wake up to charge.
What is possible is prevention of the battery being drained to 0%. So stop the system at 5 oar 10%. And then you would not have to worry about the locked situation. And then making sure nothing is at the low temp cut off for charge.
The temps were fine. It was days later when it was 80 degrees and full Sun.
It was odd, the voltage across battery terminals was like 2-3 volts. They were OFF. When I turned them back on they showed 24+v like they should.
Where was this odd 2-3V coming from.
Had to manually turn them back on, which is annoying trip out there.
Also im not sure if it’s a battery issue with SOK firmware but when the “charge” got turned off due to temp, the SOK would show 0% to the Cerbo GX. (we are using the batteries for the SOK). They have comm ports on the batteries.
It was still allowing discharge, but not keeping track of the SOK right once the “charge” was turned off.
This is information the BMS sends and does not require the GX to think about itor interpret. If it is not correct its most likely battery issue.
At 24v they probably had hit a low cut off. Either on a cell or that may be their actual total voltage cut off. I haven’t used them personally but have had battery bms from other brands switch off there (even though the data sticker days different)