48volt club car limthium battery exploded

[BBBHC]

Originally Posted by DaveTM

Just WOW!!! And like the other post, I'm glad you're OK.

I can't help but think running the voltage down to a point where the charger would start had a lot to do with this. I have no resource that tells me this is so......just a gut feel.

We have all read about the dangers of lithium batteries and how they will fail if the voltage is drawn below the "knee", and if any given cell is overcharged.

As Sergio stated, redundancy in the systems is never a bad thing.

I copied this line from a search. There are many scientific papers I read through, but this sums it up in a more brief manner...

Under-voltage / Over-discharge
Rechargeable Lithium cells suffer from under-voltage as well as over-voltage. Allowing the cell voltage to fall below about 2 Volts by over-discharging or storage for extended periods results in progressive breakdown of the electrode materials.
Anodes
First the anode copper current collector is dissolved into the electrolyte. This increases the self discharge rate of the cell however, as the voltage is increased again above 2 volts, the copper ions which are dispersed throughout the electrolyte are precipitated as metallic copper wherever they happen to be, not necessarily back on the current collector foil. This is a dangerous situation which can ultimately cause a short circuit between the electrodes.
Cathodes
Keeping the cells for prolonged periods at voltages below 2 Volts results in the gradual breakdown of the cathode over many cycles with the release of Oxygen by the Lithium Cobalt Oxide and Lithium Manganese Oxide cathodes and a consequent permanent capacity loss. With Lithium Iron Phosphate cells this can happen over a few cycles .

[BBBHC]

Originally Posted by scottyb

This builds a case for a quick release method for quick removal of the pack.

I agree. However, for those of us with a 10-14 module pack, it's a bit unrealistic. For those with a 7-5 module pack, it could be doable. I'm thinking a Anderson style disconnect for the battery cables, and "fastened" with some kind of toggle fasteners. Can't seem to find what I have pictured in my head at the moment, I know I've seen them...

[DaveTM]

Originally Posted by BBBHC

I copied this line from a search. There are many scientific papers I read through, but this sums it up in a more brief manner...

Under-voltage / Over-discharge
Rechargeable Lithium cells suffer from under-voltage as well as over-voltage. Allowing the cell voltage to fall below about 2 Volts by over-discharging or storage for extended periods results in progressive breakdown of the electrode materials.
Anodes
First the anode copper current collector is dissolved into the electrolyte. This increases the self discharge rate of the cell however, as the voltage is increased again above 2 volts, the copper ions which are dispersed throughout the electrolyte are precipitated as metallic copper wherever they happen to be, not necessarily back on the current collector foil. This is a dangerous situation which can ultimately cause a short circuit between the electrodes.
Cathodes
Keeping the cells for prolonged periods at voltages below 2 Volts results in the gradual breakdown of the cathode over many cycles with the release of Oxygen by the Lithium Cobalt Oxide and Lithium Manganese Oxide cathodes and a consequent permanent capacity loss. With Lithium Iron Phosphate cells this can happen over a few cycles .

I've re-read the post and, unless I missed it (currently suffering from the flu..so anything is possible) you don't say if you have a 7 module setup...or a 14 module.

In any event, if it were a 7 module setup, at the "36-V" your buddy ran 'em down to would put your cells at 2.57-V each. (Assuming all cells in balance...if not, one or two cells would be less)

The graphs of the "knee" of leaf batt's show that at 2.5V, the cells are just about completely dead. If you have a 14 module setup...it's even worse.

You stated that you thought the voltage was 36V when the cart stopped. If the voltage was 35V, per cell volts are even worse.

As for the BMS, such a low voltage begs the question(s) ----Do you have a LV cutoff? If you do, was it overridden in some way?

Based upon the limited information you have provided (I'm not being critical of your post....I'm just saying I don't have all the information that perhaps I should....I am, to say the least, very proud of you to post this. It's a lesson that is a "must" for lithium conversion owners!!) my current limited "conclusion"...for lack of a better word....is that your LV cutoff may not be working...or was overridden.....and the bigger lesson is, if anyone runs the charge down to below the "knee"....just open up your wallet and buy a new pack. Don't take the chance of such an event happening to you.

[Volt_Ampere]

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

[Jerald j]

The low voltage cutoff must have not been working as the pack would not stop at 40v as it should have. Also yesterday I spent about 3 hours cleaning up the mess, all that was left is the fame and rims, the fire was actually so hot it managed to melt the frame, I will post pictures later tonight when I get home from school. It was crazy to go though all it and see what parts used to be what (not much was left) but a few burnt speakers and peices of metal. I filled 2 big trash cans worth of burnt plastic and material.

[NCPW]

Tell us; after they found out you were okay and the house was intact, how mad were your parents???

[Jerald j]

Not mad, although I’m 14 I’m a young businessman as some people would call it, I have a lawn buisness and a snow removal buisness that is very successful, and I’ve always loved working with my hands, so I started buying broken 4 wheelers, dune buggy’s ect and fixing them and selling them. I paid for a lot of things on the cart and no one was hurt, the house wasn’t burned down so I’m not in trouble.

[Sergio]

Hopefully the lesson here is that properly working with lithium batteries without spending money on a commercially engineered turn key solution requires a lot of research and learning the technologies involved.

[izzybird]

Were any program changes made to the BMS or was it using the default settings?
I was up till 2 am waiting for my charger to kick off thinking of your unfortunate circumstance. All my cells were perfectly in line and I had a full volt of buffer zone, but I just could not walk away.

[izzybird]

Originally Posted by Sergio

Hopefully the lesson here is that properly working with lithium batteries without spending money on a commercially engineered turn key solution requires a lot of research and learning the technologies involved.

Very well said sir.