BMS shutoff

[T2shay]

Good morning,

This off grid thing can be a challenge sometimes. One of my 48v ruixu 100ah batteries BMS apparently got over charged when I hooked up my generator to charge all 4 batteries. The battery on the bottom shut down completely.

The batteries state that they can charge at 50amps or less. I have the inverter (renogy 48v AIO 3500W) set to charging at 40amps. So I'm not sure why it tripped my bottom battery?

I have reset the BMS on that specific battery, however any charge period trips it again.the battery actually powers and works with the house if it's not being charged with anything. However as soon as even 100w of charge hits it, then it trips again and shuts down. I have literally 300watts coming in from the solar panels because it's extremely cloudy and it is showing a blinking red alarm light for over charging on one of my other batteries now. I have no idea if my bottom battery is shot or not.

Any help is greatly appreciated

 

[Hardergamer1]

What SOC is the battery at, is one or more cells at max cell cut-off voltage? but I keep seeing people having problems with Renogy BMS lately.

I missed it's not a Renogy battery.

 

[T2shay]

What SOC is the battery at, is one or more cells at max cell cut-off voltage? but I keep seeing people having problems with Renogy BMS lately.

I missed it's not a Renogy battery.

All 4 batteries are at 51.9v ask for the individual cells I have no idea as I don't have a cable yet to inform me of each cell or program.

As soon as I hooked up the generator to charge batteries it tripped all 4 at least the warning light started blinking, except the bottom one actually shut down. I just read something in regards to charge protection mode?

As of right now I disconnected the solar panels and all 4 batteries are running the house fine. But as soon as I turn the solar panels back on it trips the bottom one again and turns it off.

 

[T2shay]

Finally got all the batteries BMS to reset. However my 2000w Honda generator continues to trip my batteries BMS for some reason. Any ideas?

 

[Hardergamer1]

You said bottom battery, so are they rack batteries? if so can you take the top off and test each cell with a multimeter? As it does sound like an out-of-balance battery to me, one way of tasting for an out-of-balance battery without the data lead, is to run it down a little, say 2-5% and then put a light charge back into it, if it then accepts some charge that then points to cells hitting max cutoff voltage.

I just add, what is the charge voltage set at? and I take it the batteries aren't close to freezing.

 

[chrisski]

In other posts, people have fixed generator problems by starting at a low amperage and working their way up. Maybe 5 amps.

 

[Hardergamer1]

In other posts, people have fixed generator problems by starting at a low amperage and working their way up. Maybe 5 amps.

Both his generator or 300w from solar are tripping the 4 batteries, this could be in how the AIO is set up, if the batteries are ok.

 

[chrisski]

Both his generator or 300w from solar are tripping the 4 batteries, this could be in how the AIO is set up, if the batteries are ok.

I missed that half of the post. Without individual cell voltage, I have nothing.

 

[T2shay]

You said bottom battery, so are they rack batteries? if so can you take the top off and test each cell with a multimeter? As it does sound like an out-of-balance battery to me, one way of tasting for an out-of-balance battery without the data lead, is to run it down a little, say 2-5% and then put a light charge back into it, if it then accepts some charge that then points to cells hitting max cutoff voltage.

I just add, what is the charge voltage set at? and I take it the batteries aren't close to freezing.

My charge voltage is set at 56v and charging is set at just 40amps. I went to mess with the settings and lowered the inverter/charger charging amps. Yet it ended up tripping the bottom 3 batteries. It is about 35°f. In the room and batteries seem fine.

They are 48v 100ah server rack batteries. I keep reading things about a resister or something. I was contemplating on discharging them to 40v and then recharging them

 

[T2shay]

I have a cable on the way to hopefully read the batteries. I literally got them 2 weeks ago roughly and did a full charge on each battery

 

[Hardergamer1]

35f, which is just above freezing, then this is likely your problem, and as you said the bottom one had the problem first which will be the coldest one too, I have had LFP BMS shut down at 4c 39f before.

Just so you know, low temp cut-off will normally still let you take power out, but stop you putting any in.

 

[T2shay]

35f, which is just above freezing, then this is likely your problem, and as you said the bottom one had the problem first which will be the coldest one too, I have had LFP BMS shut down at 4c 39f before.

Just so you know, low temp cut-off will normally still let you take power out, but stop you putting any in.

That is quite frustrating as I thought it would be good. I will heat the room up and see what happens. Cause if that's the only issue I'll be good with that.

 

[WrenchLight]

The battery on the bottom shut down completely.

When you say shut down completely, does that mean discharging is also disabled?
When the battery gets fully charged, disabling charging is normal to prevent overcharge, but it sounds like more than that is going on. Usually the alarm light for overcharge means one cell went over the maximum limit and the BMS set the alarm and communicated that to the inverter. But at 51.9V, that's not fully charged for LiFePo4.
When charging gets disabled due to overvoltage, say one cell goes over 3800 mV, it needs to go below say 3600 mV before charging gets re-enabled. Of course, this all depends on the BMS settings.
Some things to check: what max and min cell voltage allowed in the inverter settings, read or measure cell voltages in the batteries to see if they're unbalanced.
If it's unbalanced, and won't charge due to overvoltage, then you may need to individually charge each cell with a single cell charger to top-balance the battery pack.
There's one more thing that can be happening. One of the voltage monitor wires to a cell may have a bad connection. If the BMS reports two adjacent cells with one going high and the other low at the same time when it's trying to balance the cells, check that connection.
Edit: I missed the posts about the temperature while I was typing. Yeah, that totally makes sense. See if the inverter has settings that will ramp down charge rate when it's below around 8C and taper to zero charge at 0C.

 

[T2shay]

When you say shut down completely, does that mean discharging is also disabled?
When the battery gets fully charged, disabling charging is normal to prevent overcharge, but it sounds like more than that is going on. Usually the alarm light for overcharge means one cell went over the maximum limit and the BMS set the alarm and communicated that to the inverter. But at 51.9V, that's not fully charged for LiFePo4.
When charging gets disabled due to overvoltage, say one cell goes over 3800 mV, it needs to go below say 3600 mV before charging gets re-enabled. Of course, this all depends on the BMS settings.
Some things to check: what max and min cell voltage allowed in the inverter settings, read or measure cell voltages in the batteries to see if they're unbalanced.
If it's unbalanced, and won't charge due to overvoltage, then you may need to individually charge each cell with a single cell charger to top-balance the battery pack.
There's one more thing that can be happening. One of the voltage monitor wires to a cell may have a bad connection. If the BMS reports two adjacent cells with one going high and the other low at the same time when it's trying to balance the cells, check that connection.

The a red led light turns on and all the green lights shut off. So I unhooked the battery from everything turned it back on and reset the BMS by a switch on the battery. At that point the battery can discharge but if I attempted to charge it what so ever it would immediately trip the BMS again.

So I reset the battery again. This time unhooked up the generator and it ended up tripping the bottom 3 batteries. Where I had to restart them once again. It's like I can't get them to charge. I first noticed an issue when we had sun the other day it was doing around 1800watts and started setting off the alarms on the batteries.

The batteries are brand new so I'll check and make sure I don't void a warranty cause that would be shitty for sure. If this is something I have to do regardless of being new or not then absolutely I'll tear them apart.

I've been slowly discharging them all day now. Hoping the get that cord so I can individually check the cells.

Inverter doesn't allow anything in that regard that I'm noticing at all when it comes to temperature.

 

[T2shay]

Ok, had the room at 75°f. Turned the solar panels back on bringing in about 1000watts. Bottom 3 batteries started flashing red. Couple questions.

The wire from the solar panels right before they go into the inverter show about 122v coming in. Once I hooked them up to the inverter and it starts to recover power. Those same wires read about 160v, any reason why? As the inverter is only rated for 145v open circuit.

Also being server batteries in a case with a long bus bar. Do the wires coming from the inverter to the batteries have to be on opposing ends of the bus bar for equal charging? Or can they be both on the top of the bus bar?

 

[740GLE]

Id reverify each battery/charger connection and dip switches.

Almost seems like the charging current is entering the bottom batteries and minimal is reaching the top.

 

[T2shay]

Id reverify each battery/charger connection and dip switches.

Almost seems like the charging current is entering the bottom batteries and minimal is reaching the top.

Do i need to mess with the dip switches if I'm not currently connected to a computer to monitor them?

 

[T2shay]

Ok so still having this issue. I was using a multimeter to see what voltage is going to the bus bar for all 4 batteries. 117volts is entering the busbar. Is that normal? Does it disperse that evenly or is that possibly hitting one battery?

Thanks again for all the help

 

[740GLE]

what’s being used to charge the battery that could provide that high a voltage?

Are you measuring ac or dc?

 

[T2shay]

what’s being used to charge the battery that could provide that high a voltage?

Are you measuring ac or dc?

It was the solar panels 6 450w panels. It was pushing about 1600watts. I took the multimeter to the cables going from the inverter/charger to the bus bar. I tested where the cables touched the bus bar.