Inverter

[mranderson19]

I discharged my 48volt batteries to 26 volts and inverter won’t charge them. Will I have to by a lithium battery charger to charge them up enough for the inverter to do it? That would be a shame because I have a Growatt 12kw inverter.

 

[DThames]

You said "batteries". Do you have 4, 12v batteries in series, or what exactly is your setup?

 

[mranderson19]

I have (4) 48volt 5kwh batteries. After doing some troubleshooting, I believe he problem is the BMS on each of the 24volt batteries that make up the 48volt. I have tried for two days to contact Big Battery who sold them to me but have not been able to get a response.

 

[Steve_S]

I suspect the BMS went into FailSafe mode. They need to be triggered to reset.
Will has mentioned that in his Video Reviews of these. I suggest you search Will's Videos to find out what needs to be done to reset the BMS.

 

[mranderson19]

Okay, I will do that. Thank you.

 

[mranderson19]

I’m a little confused on settings for the Growatt inverter. Where exactly do I put the max charge and discharge of batteries and does that also tell the inverter when to switch to solar or utility supply. I have it set at SbU.

 

[DThames]

Did you ever get your batteries to wake up? If you disconnect the batteries from each other, are some of them showing zero volts? You might try getting a dumb charger or series up some 18650 cells to have 25v or so, something above your single battery, and connect it for a second to make the BMS think it is taking a charge. Or you might have to keep some charge on there until the voltage is up above some cutoff minimum.

 

[Dzl]

I discharged my 48volt batteries to 26 volts

26V, wow! ?

I have (4) 48volt 5kwh batteries. After doing some troubleshooting, I believe he problem is the BMS on each of the 24volt batteries that make up the 48volt.

If your 48V batteries are sitting at 26V it sounds like multiple layers of protection failed.

 

[Hedges]

26V sounds like a decent voltage for a 24V pack.
If 48V is two, 24V in series and one has switched to zero output (hit low voltage disconnect, that could explain it.
Probably doesn't have anything like bypass diodes, so can't pull current from it. It would have to present some non-infinite impedance for voltage of the other to be measurable externally.
Can you access the individual 24V packs you think make up the 48V?
Have to see if there is a way to reset the 24V pack that shut off.

 

[mranderson19]

I went into the cabinet and partially opened up the 24 volt batteries that were inside. I checked the voltage before it entered the BMS and it was good (about 27volts) that tells me it is a BMS problem. Another cabinet shows good voltage going out of the BMS which tells my limited knowledge it must be the breaker that is built into the cabinet. I contacted Big Battery (the only way was through texting) and they are sending me parts that I hope will fix them.