Well there you go...

[tevek]

After a less than successful weekend converting my receivers over to Crossfire which ended well, I had a problem battery that I was trying to resurrect.
Checked every ten minutes and then it all went south.it Wife called out, smoke alarms went off. Result was two batteries on fire, both chargers destroyed and obviously the batteries are toast.
Be careful out there peeps.

 

[coyote_dc5]

Wow, so what was the situation. Symptoms, visual on lipo itself and charging process? Be good to know this along with the manufacture of the cells so others can watch out and avoid this.

 

[HighTechPauper]

Sorry buddy, but I am glad you and your home are safe after this near catastrophe!

 

[tevek]

Wow, so what was the situation. Symptoms, visual on lipo itself and charging process? Be good to know this along with the manufacture of the cells so others can watch out and avoid this.

One of the batteries (4S 650 mAh TBS Graphene) was giving me grief with excessive voltage sag and I was charging it along with another battery of the same brand and capacity. Charging at 1.3 A and checked every ten minutes, both cool to the touch and appeared to be coming along nicely.
Both batteries were new with no more than ten cycles through them, smoke alarms went off and the wife was in the room frantically moving my quads away from the fire.
I had only posted a thread recently regarding charging batteries etc and then this happens... Probably just as well I never charge batteries without being close by and check them frequently, I had only just sat down and my wife had walked back from the laundry as it all happened.

 

[Wayno52]

Wow, that's nasty buddy. I'm always so careful when charging as I think most of us are. Just goes to show sometimes stuff just goes on no matter how careful we are.

 

[tevek]

Wow, that's nasty buddy. I'm always so careful when charging as I think most of us are. Just goes to show sometimes stuff just goes on no matter how careful we are.

Yep, was a pretty underwhelming experience. Respect for the **** things just went through the roof.

 

[coyote_dc5]

That is scary. So was that a parrallel charge or independent both at 1.3a? Did the bad cell show any signs of swelling at all or damage anywhere? Just amazes me some sag and it goes like this. I have a few cells which sag quickly but I'm still using them hence why I'm asking so many questions

 

[tevek]

That is scary. So was that a parrallel charge or independent both at 1.3a? Did the bad cell show any signs of swelling at all or damage anywhere? Just amazes me some sag and it goes like this. I have a few cells which sag quickly but I'm still using them hence why I'm asking so many questions

Nah, they were in parallel and absolutely no signs of swelling. I was trying to resurrect the battery with a gentle rated charge and it literally caught fire about two minutes after I walked to the front of the house. I’m parking up any batteries that show excessive sagging at the end of the flight (14V - 12.5V), not going through that again. With sagging, I’m talking about batteries that simply plummet at the end of a flight.

 

[coyote_dc5]

Did you notice after the previous charges when plugged into a cell checker whether one of those cells hadn't charged properly? I'm wondering if you had a duff cell for a while and didn't notice . Symptoms don't seem too excessive to me, that's why I'm so surprised it just went up like that even on a light recovery charge . Scares the hell out of me tbh

 

[tevek]

Did you notice after the previous charges when plugged into a cell checker whether one of those cells hadn't charged properly? I'm wondering if you had a duff cell for a while and didn't notice . Symptoms don't seem too excessive to me, that's why I'm so surprised it just went up like that even on a light recovery charge . Scares the hell out of me tbh

The voltages between the the four cells was about 0.1V which suggested it may have been a simple charge to bring it up to speed. As I mentioned earlier, the battery was about ten cycles into its life and I’ve done hundreds of times before, a simple charge/watch and put it back into service.
You mentioned duff cell, that’s an old Navy term that we used back in the day.