48volt club car limthium battery exploded

[DaveTM]

Originally Posted by Volt_Ampere

7 and 14 module voltages are the same. The modules are two in parallel.

Thank you for the correction V_A. This flu is not fun!!

Just a note, but my LV cutoff setting on my BMS is set at 42V. I have a note on my documentation that I obtained this information from the EV web site. This minimum is 3.0V per cell.

In addition to the BMS setting, my Alltrax controller LV pack cutoff is set at 39.6V, which should be 2.83V per cell....assuming all cells are in balance. The Alltrax setting is the redundancy LV setting in case the BMS went "on vacation."

[izzybird]

I don’t think (opinion) taking the cells to around 2.6v was the killer, his BMS at default is 2.7v LV and plenty of EV companies have taken them down that far or more in their testing. They could have gotten out of balance at that low end, charged to what I feel is too high at 4.2v, and the BMS didn’t get the job done??

[Jerald j]

Nick from ev battery center a while back told me that there would be no damage done unless the battery pack voltage got to zero

[Sergio]

Originally Posted by Jerald j

Nick from ev battery center a while back told me that there would be no damage done unless the battery pack voltage got to zero

Sorry, that is not a correct statement that can be made remotely without analyzing the pack.

There is no way to know the voltage on each individual cell in the pack unless it was measured.

There is no way to "visually" see any damage caused by shunts or dendrites that grew inside the pouches.

While damage is not necessarily done by allowing excessive discharge, You need to carefully monitor the cells under a controlled current charging to make sure they are behaving as expected.

Installing a temperature probe can also help catching a cell failure down the road before it goes into a thermal runaway.

[MyCousinVinnie]

At this point, we are all speculating as to what happened. Like others, I'm glad there was no harm to person or property other than the golf cart.

I have a question - you mentioned that it was over-discharged. Did you have the BMS on at that point? If so, was there a relay installed for over-discharge protection? If so, what type?

[Jerald j]

As I said I am not sure really what ev battery centers bms systems have on them, but the WiFi bms would hookup to a web adress and it would say discharge/charge enabled/disabled and had options to start and stop balancing the cells, also to enable and disable charge and discharge then another one for the WiFi frequency I believe, but I checked the cells they were balanced as of when I got home

[Volt_Ampere]

The stuff I got from EV three years ago did not have an over discharge circuit - only an over charge over voltage circuit. I built my own BMS to replace the one Nick designed.

[bronsonj]

Glad nobody was hurt!

Jerald, do you know what the full V after a full charge was on your pack normally? Was it charging to 4.2vpc? Higher? Lower?

DaveTM, If the BMS is set to 42V cutoff (3.0vpc) why then not have the Alltrax shut off at 42V as well? This way if the BMS fails then the Alltrax will help save your pack?

[DaveTM]

Originally Posted by bronsonj

DaveTM, If the BMS is set to 42V cutoff (3.0vpc) why then not have the Alltrax shut off at 42V as well? This way if the BMS fails then the Alltrax will help save your pack?

IIRC I don't think there is any benefit of both having the same settings.

You're asking a question about two separate components that do two different things. The answer is more complex and can't be answered in one or two sentences.

The settings are very close. I'm relying on the ZEVA per cell LV first. If that fails, then I'm relying on the Alltrax pack LV second.

[BigOL3]

Like everyone said, I am glad no one was hurt and your home is safe. Additionally I am really impressed with jerald, not only for the quick thinking on his feet and swift action in getting it outside, but also for being so knowledgeable on installing the lithium battery setup at such a young age ....... WTG jerald!

I was already 90% certain converting to lithium would be a bad idea for ME to attempt, since I would need to learn it all from scratch. After reading this, I am now 100% certain the installation is waaaaay too critical/dangerous for a novice. I like my home and really don't want to see it go up in flames!