Man that sucks!!!
NEVER connect the balance leads to the positive section of the cells.
I run all the overlaps and balance off the negative terminal meaning its impossible to short out even if the battery bounces all over the show.
I would guess that somewhere something chaffed through and shorted on of the cells…
I just can’t imagine the balance leads coming off the side here along with 2 layers of rubber sheet wrapped around it, but I hear what you’re saying.
So if you connect all balance leads to negative ends (plus the last positive) and one came loose and touched its neighbouring connection, how would that not short?
30q don’t burn , get to 140-150C , my guess : short cut in carbone case ( bms?) under the stuff that burns , really sorry to see that 
Have you find some cells ?
What a loss! Sorry to see this 
Better start that second build soon before Covid is gone 
I was leaning towards BMS as well but when I checked the app this morning the cells looked normal, theres no carbon on the inside. I guess we will never know, It may not have been the battery at all and something wrong with the van. The Fireman couldn’t determine if it started in the front or in the rear.
Witch BMS you using?
To make matters worse, the company i work for it happened in their vehicle and they only pay out a maximum of £250 for personal items. 
I am sure the BMS burned down all!
I think you could be right, In hindsight I should have paid a little extra and opted for one these instead
https://www.energusps.com/shop/product/tiny-bms-s516-150a-750a-36?category=4
I know it because I use the same BMS.
Some weeks ago I am sitting in front of my Batteriepack and see how smoke comes out from the left BMS.
Some seconds later the Batteriepack standing full under fire. I catch theme and throw out theme. I not want to burn down the office.
Outside I use one big cutter and cut the cables to the BMS. ( between i extinguish fire )
After I cut all Cables I was able to stop the fire, before not!
I am shocked about such dangerous products!
Holy S**t No Way, thats crazy! Such a dangerous product!! Good job it happened in front of you and you were able to do react in time!
I’m just glad it was in the van parked in the middle of nowhere and not in my garage on its own or parked outside my house.
Well, seems you learned the hard way, BMS are dangerous!
Same crap with Antispark switches.
Use a good welded pack and Antispark plugs and you are on the safe side 
Well, maybe not really, but eleminating dangerous componets is a wise Idea 
Certainly learnt the hard/expensive way!
I think a BMS is a handy and a good thing to have in a battery setup, Just not cheap and nasty Chinese ones.
Hi.
I’m so sorry for your loss. But, it could have been much worse. Could have easily burnt your house down. 
It sounds like it was the BMS to me. I have had several BMSs malfunction on me. Mine didn’t catch fire but, the PCB board looked melted and burnt a couple times. Twice on a Onewheel, one on a electric skateboard. Since then I have removed all my BMSs. I balance charge externally with a hobby charger, and monitor individual cell voltage during use.
Besides burning your house down, BMSs are just one more thing to fail. I had to walk home more then once due to a failed BMS. I don’t want to have to swim back to shore because of a BMS on an e-foil.
Thank you for sharing this experience. We all need to take this as a lesson learned. Everyone needs to think safety about how you charge and store your batteries. They need to be in a fireproof enclosure whenever they are unsupervised.
I recommend building these batteries with individual cell fusing. Fuse the battery wires, and fuse the balance wires. That’s how I built mine but I still take the fireproof box precautions.
Samsung 30q cells do thermally runaway.
My battery is 196 of these cells. That’s a huge fire.
It’s not about coming loose. When you wrap the nickel over the edge like you have, there stands a chance than the with time it might chafe against the cell insulation. If its welded on the positive, it will mean it chafes onto the negative and then shorts.
But if another here has had a BMS fails there’s a good chance it could be that too. None of my batteries have the BMS on them. I only connect a BMS when the battery charges and then I run a “dumb” battery. Less chance of failure while doing nothing…
@Flightjunkie I’m sure you have told this already, but how do you charge your 7S14P setup (one bank/site) with an iCharger that can only do 6S Lipo / Lilo / Life max.
Ahh I see what you mean. Well that rules that out also as the nickel was only bent over around 5mm and didn’t go past the cell holder.
I think the BMS is the culprit, I never considered using one externally for charging.
The answer is here:
The X6 has a big brother: the iCharger X8 - 8s 1100W output - for 130usd. Twice as much as the iSDT Q8, 8s too but 500W output only for 60usd .
, a smart BMS from 
