Did I kill my BMS …..twice!

[Bushbeast]

Hello all,

I have a Luxpower 12k US that I tried to hook up with 2 10kw 16s lithium batteries (I have learnt they have the Pace 100a BMS in them). With the battery breaker off I connected the CAN cable of the first battery to the inverter and the communication cables betweeen the 2 batteries. The onboard battery screen reported primary batter had 85% charge and the secondary battery screen read 20% state of charge. With the battery breaker at the inverter still off I could see the higher battery was discharging at @9A into the lower battery. Both battery screen reported the same current rate battery 1 -9a battery 2 +9a. At this point l checked the inverter and it was showing a green battery symbol and 85% SOC…. So with that I assumed all coms were good. I therefore switched the battery breakers on and immediately battery 2 switched of. No screen no green lights etc. Battery1 continued happily and the inverter started charging it further.

I therefore disconnected battery 2 but cannot get it to switch on at all. I tried the jumper from b- to p- thing but still it seems dead. Multimeter reads 52.5v all cells and individual cells all read 3.296. I therefore thought this was a duff battery BMS. I have a third battery that I hadn’t wired into the system as yet so I swopped it into position 2. Went through the same setup procedure as above. Again once I switched the inverter battery breaker on battery 2 died (instantly)…..frig! Same thing can’t get it to come back on.

Battery 1 is still happily chatting and charging with the inverter. I wired the + from both batteries through a 150a dc breaker to a bus bar. Both - to a bus bar then took one + lead and one - lead from those bus bars to the inverter where I put them into their corresponding + and - ports in the inverter. (Which on the 12US leaves 1 + and 1- battery hook up free in the inverter.)

Have I killed the BMS (twice) somehow? I there something I have done wrong that’s immediately obvious? Battery 1 is happy?

Thanks

 

[Bushbeast]

Sorry, forgot to add….technically I don’t have a 12k it’s at a friends house I was helping him put his system in….helping as in killing batteries

 

[Brucey]

So best practice when paralleling batteries, charge them all fully first.

It's possible your 20% soc battery triggered it's BMS protection when the current surged when you turned the battery breaker on, while the 85% unit didn't.

 

[Bushbeast]

So best practice when paralleling batteries, charge them all fully first.

It's possible your 20% soc battery triggered it's BMS protection when the current surged when you turned the battery breaker on, while the 85% unit didn't.

Thanks Brucey

I have a charger on the way so will put one of the batteries on charge. I did try putting one of the batteries on it own to the inverter (having disconnected the working battery), but the inverter just reports no coms gives me a red battery warning and therefore won’t charge it. I suppose I could have tried changing the battery setting to lead acid to force it to charge, but if the BMS is asleep/dead the shunt b- to p- will be open so won’t charge the battery anyway would it?

I have the battery case open now so could bypass that I guess

 

[hogback]

The batteries should be at much closer soc before paralleling. I'm surprised they only were swapping 9A in that configuration. Maybe I am not following your description properly.

 

[Bushbeast]

The batteries should be at much closer soc before paralleling. I'm surprised they only were swapping 9A in that configuration. Maybe I am not following your description properly.

I think they were swapping at a higher rate than that initially but slowly wound down to that or 9.6a or something

 

[Bushbeast]

I do know that when I attached the good battery to the dead one after all of this to try to simulate charge it would not wake the other battery up….that’s what has me concerned that I may have killed the BMS……