I consider myself to be fairly knowledgeable about battery chemistry and the possible hazards posed in their use. However I got caught out yesterday.
I very rarely charge my batteries at home, instead I charge while at the field. Yesterday I decided to maiden a Zohd Dart Extreme XL, and as I intended to just do the maiden flight and come straight back home (health reasons) I decided to charge a single 3000mAh 4S Nanotech pack at home while I got everything in order for the maiden.
The pack I was using had only three previous charges to its name, had not been abused, and prior to charging all four cells were at 3.8Volt. I started the charging process, charge rate set at 1C (3Amp), balanced, and got on getting my gear ready, at no point did I leave the room.
After about fifteen minutes I started to detect the faint whiff of warm plastic. I went over to the charger to find one of the cells of the battery extremely swollen and the heat shrink wrapping smoking. I quickly pulled the battery off the charger and ran out into the garden with it. I threw it some distance from me and before it hit the ground it flamed up violently.
This has been quite a rude awakening for me, as in the past when Iāve heard similar stories I was convinced that it was human error. An example would be one of our club members thought that to charge at 2C you doubled the voltage. He ended up burning his conservatory down. Here I thought I did everything right. I physically checked the battery, looking for any signs of damage, checked the pre-charge voltage, even checking the internal resistance, and all checks indicated a 100% healthy and safe LiPo battery.
My lesson learned here is to never assume the best but expect the worst. Even though I followed my own strict charging process I count myself extremely lucky that I still have a roof over my head, and though I followed my own strict charging routine BAD THINGS CAN HAPPEN!
I know that some might suggest I should have used a LiPo safe charging bag. I think if I had I would not have been alerted by the smell of warm plastic, and the LiPo would have detonated on the bench.
Just glad to hear you caught it in time Nidge and you managed to get it out without damage or injury to yourself or your home. As fpv season is upon us, this is a timely reminder to us all to stay alert and aware and to not leave the room when charging our batteries even if pre charging checks pass ok. Thanks for the warning Nidge and stay safe everyone
I would say it was maybe just over a year old and had only been used three times, lightly. It was the last thing I bought from Hobbyking before the UK warehouse closed.
Couple of years ago I decided to dust off my pre-DJI Hubsan 501s / recharge itās batteries, prior to sale.
Appeared to charge OK using original balance-charger, bit swollen, didnāt think much of it (ā¦duh ). Thought Iād carefully stick a pin in each (carefully/sidewards) to just nick the PVC-sheath & let āwhateverā outā¦next thing Iāve got a couple of batts whooshing black smokeā¦ingress of air must have set it off - only just managed to get them outside
! Never again - slightest bulge in any (DJI) batt, no more āfixingā ! Incidentally, what do you do with ābulging battsā - bit unsafe to just dump in nearest batt-bank (esp. if itās in-store as opposed to a Council skip) - apologies if an answer has already been suggested.
Discharge them safely. Easiest is in a bucket of salted water in the garden for several days. After down to very low voltage per cell I take them to the tip and put them in the battery skip.
Wow. I must get better with my charging then. I too assumed if you did checks and werenāt silly itāll be fine ā¦
Actually saw my first lipo fire 2 weeks back at drone circle, but that was me donating a battery that had the previous day taken a slide down the willington towers and didnāt look good. Donated to some kids who charged a 4s at 8s voltage. Tbh think they got to 28V before it went!
Sounds like I have been and still doing it all wrong. I donāt understand about or why itās needed to check volts befor chargingā¦ Ive been charging mine by going by the coloured lights on the chargerā¦ Have been doing that for all me rechargeables.
Recently since advised by not a pretty boy. I only fully charged for immediate useā¦
Think I stop charging and going out for the dayā¦
Our council starts a collection battery recycling scheme this week. Small i.e. not car batteries, can be left.out in small clearly labelled containers, like an old margarine tub. To be left on top of the recycling bins, not in them. One of their few good ideas.
Question: I am new to all this but for a previous hobby I used LiPo batteries and used a fireproof charging bag when charging them. Do you guys use / recommend a charging bag for charging Drone batteries?
I think I wouldnāt have noticed my Lipo was about to fail if it was in a āchargingā bag as it was the smell of cooking plastic that alerted me. I do use the safety bags if Iām transporting LiPoās with other items that could pose a puncture risk.
). Thought Iād carefully stick a pin in each (carefully/sidewards) to just nick the PVC-sheath & let āwhateverā outā¦next thing Iāve got a couple of batts whooshing black smokeā¦ingress of air must have set it off - only just managed to get them outside 
tip, sounds most useful!