200 amp/h LiTime 100 amp BMS shutting down

[ff6849]

Used my 2-200-amp Li-Time batteries (100-amp BMS) wired in parallel for the first time this weekend camping in a RV and the BMS would randomly shut the batteries every morning (3 times). I was able to re-start them from my friend’s generator by plugging into the shore line. I had 13.2 volts when the BMS did the shutdown, and 13.2 volts after. I have 2000 XC Xanthrex Inverter, with 5500 Onan, and 200 watts of solar (upgrading to 960 watts soon). The mornings were chilly but never below 40 degrees. The system worked fine during the trip and was running my generator during the day to keep the batteries charged. I was running my propane RV heater during the night but that was the only real draw on the system. What my concern is why is the BMS shutting the batteries. One time the shut-down occurred when starting the generator, the other times it just shut down, again at 13.2 volts. I have email LiTime and their response is that I shouldn’t use their batteries to start the generator. Any suggestions as to what is going on.

 

[sunshine_eggo]

Used my 2-200-amp Li-Time batteries (100-amp BMS) wired in parallel for the first time this weekend camping in a RV and the BMS would randomly shut the batteries every morning (3 times). I was able to re-start them from my friend’s generator by plugging into the shore line. I had 13.2 volts when the BMS did the shutdown, and 13.2 volts after. I have 2000 XC Xanthrex Inverter, with 5500 Onan, and 200 watts of solar (upgrading to 960 watts soon). The mornings were chilly but never below 40 degrees. The system worked fine during the trip and was running my generator during the day to keep the batteries charged. I was running my propane RV heater during the night but that was the only real draw on the system. What my concern is why is the BMS shutting the batteries. One time the shut-down occurred when starting the generator, the other times it just shut down, again at 13.2 volts.

200W PV is nothing vs. 5.12kWh of battery. You would need 8+ days of full sun exposure to panels flat on the roof to fully charge your batteries from empty.

Did you take the measurement at the battery terminals?

I have email LiTime and their response is that I shouldn’t use their batteries to start the generator. Any suggestions as to what is going on.

Have to concur with this. The surge from starting current likely well exceeds 100A. LFP batteries are terrible starter batteries unless specifically designed for it.

 

[Partimewages]

I believe the start current for your generator is around 300+

 

[ff6849]

I understand that the generator may have caused the BMS to shut down, but the generator only tripped the bms once

 

[Q-Dog]

Were these batteries fully charged before putting them in parallel? Fully charge each one independently, then parallel them for 12 - 24 hours, then connect them to your system?

 

[ff6849]

Were these batteries fully charged before putting them in parallel? Fully charge each one independently, then parallel them for 12 - 24 hours, then connect them to your system?

yes

 

[Q-Dog]

I assume both batteries shut down?

 

[sunshine_eggo]

What is the inverter cut off?

Are all battery connections, interconnects, etc., properly torqued?
Is voltage drop consistent with calculations?
Are any components like switches, breakers or fuse holders exhibiting excessive voltage drop?
Any connections producing heat?
Any washers in the current path?
Any shrink pinched in any connections?
All crimps high quality?

 

[ff6849]

I assume both batteries shut down?

Yes

 

[ff6849]

I just got back last night so I haven't had a chance to really exam the system, but I am going to pull the batteries and check them individually for voltage and and try to duplicate the fault with them separately, not sure how I am going to that yet but I am researching that now. I know just enough to be dangerous.....

 

[ff6849]

What is the inverter cut off?

Are all battery connections, interconnects, etc., properly torqued?
Is voltage drop consistent with calculations?
Are any components like switches, breakers or fuse holders exhibiting excessive voltage drop?
Any connections producing heat?
Any washers in the current path?
Any shrink pinched in any connections?
All crimps high quality?

What is the inverter cut off?
I think its 10.2 volts or 11.2 volts

Are all battery connections, interconnects, etc., properly torqued?
They were, but I am going double check

Is voltage drop consistent with calculations?
Not sure how to answer this

Are any components like switches, breakers or fuse holders exhibiting excessive voltage drop?
Not that I am aware of, but I did use all high quality components

Any connections producing heat?
I didn't notice

Any washers in the current path?
No

Any shrink pinched in any connections?
No

All crimps high quality?
Yes, and high quality wire

 

[Tomthumb62]

I understand that the generator may have caused the BMS to shut down, but the generator only tripped the bms once

Perhaps the BMS has been more or less permanently damaged from the 300+ attempted amps draw to start the generator. Use a lead acid battery to start the generator, not a lifepo4.

The LiTime is popular because it's cheap. I can't imagine the BMS in there is the most robust out there. If that 300A+ draw from the generator was faster than the BMS could have fully protected against it, it might have fried the BMS just enough that it is now wonky and trip-happy with any kind of draw but only randomly. Just a guess though.