Large Model Association Forum

The warning 'Don't leave LiPo's charging unattended' is not without substance. The battery in the pics was on charge in my workshop using the same LiPo charger that I have been using for years and the battery had been charged many times. I happened to pick it up to move it to one side and noticed it was unusually hot, it was nearing the end of the charge so was pretty well fully charged. I removed it from the charger and didn't want to leave it in my workshop so placed it on a metal surface in the garden to help cool it down. After a while I heard a sizzling sound and found smoke coming from the battery, I thought this is interesting so took a photo. Within a couple of minutes the smoke erupted into flames. I suppose this is why passenger aircraft are now not allowed to carry crates of LiPos as belly cargo.

Hi Dave,
You are so right, the pictures can only yet again spell out the dangers of LiPo batteries. The owner of Whitby model shop was not so lucky, and found out to his cost the danger of LiPo's.
About 7 years ago he had a model on charge in his shop, he left it unattended for a while, only for it to explode, burst into flames and destroyed the whole shop. The first he knew of it was when North Yorkshire fire brigade were breaking his door down.
It is at your own peril to leave these batteries unattended.

Regards

Dave K

After a couple of different club members had LiPo fires in their garages, I invested in a kettle type BBQ with a well fitting lid, which is permanently outside well away from buildings. I've got a 12v power supply fed from the mains via an RCD for the charger. A bit inconvenient when its p*****g down, but better that than what Dave nearly experienced!

Very sensible Dave. I bang on about this all the time, having known a number of people who have had fires. Never charge indoors. If they go off its like a roman candle, go near it at your peril.

Dave - I'd be very interested to know if you were charging it with the balance lead connected.

How many different Daves can you get in a thread
DB

I'm Dave, and so is my wife.

Given the relative propensity for bonfire night like antics of model lithium batteries, I have my suspicions how many of them have passed the testing of UN 38.3 so they can be transported

Page 434 in the ADR below has the test T7...would you be brave enough to try it on even the most expensive model lipo?

http://www.unece.org/fileadmin/DAM/trans/danger/publi/manual/Rev.6/1520832_E_ST_SG_AC.10_11_Rev6_WEB_-With_corrections_from_Corr.1.pdf

Rob Buckley wrote:I'm Dave, and so is my wife.

"why do they call you Dave, then?" (the immortal Trigger)

Hi Gordon, in reply as to whether I was using balanced charging I have a couple of chargers but one is without balance leads. This time the balanced charger was in use on another battery so I was charging the 'firework' battery directly. I must point out hat this charger has been used countless times without a problem so I suspect that one of the cells developed a fault to cause thermal runaway. I should imagine the same could happen with balanced charging as well.
Regarding the 'too many Daves' you only have to shout out DAVE on any flightline and half of the blokes (and girls) turn to look

Sorry not much to add to this thread apart from what has already been said. But my name is Dave, does that count

Your not just any Dave !! Your are the esteemed Dave !! All seeing and all knowing !!
PS: my name is not Dave, but Hilaro Frosticos will do !!!

Mike Ellis wrote:Your not just any Dave !! Your are the esteemed Dave !! All seeing and all knowing !!
PS: my name is not Dave, but Hilaro Frosticos will do !!!

The owner of Whitby Model shop that burned down was a Dave, doe's that count?

You cannot ever charge without a balance lead. Early Li-Po's may have come without balance leads, but that was 2006! I have customers who say they 'balance charger every now and then' NO Every charge the chance of an over voltage cell is high, even charging well below C.
You would all have kittens if you saw my charging bench, 8' 4' covered in Li-po's 100's of them. I have never had a fire that was not intended..I have blown up a lot of Li-Pos on purpose to understand the limits. I've been using them since 2004 right in the earliest days. The EDF Hawk video I posted has 14s (59v DC) at 10A (10,000mAh) capable of discharging at 10kw! I had three sets in my warehouse charging and discharging, never left alone, constantly monitored for temps (touch) and sound!! Li-Pos talk to you way before they erupt, they give off a sweat smell also.
Temperature the cells are stored and then charged at makes a difference to final voltages, never charge really cold cells they might over voltage.
There are so many variables, but Li-Pos can be perfectly safe, I charged up fourteen 2200mAh packs yesterday pm for today's flying session, I'd say I charge 30 plus packs every week of the year and have been for years, never a single issue.
BUT they are not to be underestimated, even the 1.0A packs can be scary when they let go, 4 ft of flame and a fire extinguisher is not much more than a ice pack to cool the temperature for a short time.

I'm also Dave ;-)

Speaking as a non Dave but an electrical engineer, I totally agree with Dave W. you should always use the balance lead, even if the charger says it can charge lipos, if it hasn't got a balance connection don't use it.

Barrie

Just as an aside to our modelling experiences.If you remember a while back Boeing 787's were grounded for 6 months because of the fires occurring in the lipo packs used to start the APU at the back of the aircraft. I don't know how they were charged but it was interesting to hear that the factory manufacturing the charging equipment for these batteries burnt to the ground. (info from Flight International)

This sounds like an interesting idea http://www.bbc.co.uk/news/technology-38637357

What Dave said above is all true - ALWAYS use the balance connector. BTW, I'm not a Dave.