Valence BMS Short

[Severence]

This is really weird. My Valence U1-12RT battery reads 10.8 volts at the terminals but shows no voltage when connected to any other load i.e. charge controller.
Does this sound like the BMS is fried?

 

[John Frum]

Thats 2.7 volts per cell which is pretty darn low.
What is the low voltage cutoff for the pack?
Also one or more of the cells may be below the per cell cutoff.

UPDATE: The pack cutoff is 10.0 volts or 2.5 volts per cell.

 

[Severence]

Shouldn't it still be able to power the charge controller and show some voltage?

 

[John Frum]

if one or more cells are below the low cutoff the bms protection circuit will kick in.

 

[Severence]

Wow! How can I charge it back up?

 

[John Frum]

Wow! How can I charge it back up?

We don't even know for sure what the problem is.
Try disconnecting all the loads and all the charge sources and then reattach a charger.
Then see if it will take a charge.

 

[Severence]

That's the first thing I did.
Thinkin' now I gotta reset the BMS somehow.
Got the cover off and checkin' it out but have no idea what I'm looking at.

 

[Severence]

Oh I forgot to mention,, there are 2 of these batteries that were tied in parallel and both have the same problem.

 

[John Frum]

What is the pack voltage on the 2nd battery?
Since you have the cover off what are the voltages of the strings in batteries?

 

[Severence]

If by pack voltage you mean total voltage it's 10.6 on the battery with the cover on it.
I'm kind of lost on the subject of strings.

 

[John Frum]

So one battery pack in the bank is 10.6 and the other is 10.8.
That is not awesome.
Are they in series or parallel?
Did this bank ever work?

 

[Severence]

Yes,, the bank worked great.
They were in parallel, but I disconnected everything when this happened.
The bank worked fine until I plugged a heavy load into the inverter and got the error beep from both the inverter and charge controller.
I was getting the green signal light on both units,, this morning , one is changing to yellow, and now I've got the low one attached to a fully charged lead acid battery to bring the charge back up and see what happens.
I was able to get all the Valence ops manuals and spec sheets though.
You've been more help though. Thanks

 

[John Frum]

I have no experience with these specific batteries.
What do the status lights indicate?

 

[Severence]

DUDE! YES! I hooked the FLA battery straight up (parallel) to the Valence,, it brought the Valence back up to 12.1v and now I've hooked the controller up and it shows 12.1 for the Valence. I think I have reset the BMS.
I'll keep you posted when I re-assemble everything.
Thanks again!

 

[Severence]

Typo on the previous post 12.1 volts not 21.1