EXPLODING BATTERY CELL !!!
 

Had the experience of a intellect single cell explode over the weekend.

Sharing a pitt table with another competitor in a room with another 20+ people, the cell self exploded on our table while working on cars.No one was injured.

We had just returned from our heat and started working on the cars when we noticed a battery pack (that had been charged and placed in a non conductive battery box)starting to smoke and sizzle (something that i have seen before, but only on charge or in a equal' tray) Picking up the pack it fell apart from heat. Thinking that was the end of it, some 3-4 minutes later a single cell let off a bomb like explosion as load as a shotgun.

From this experience if anyone witnesses this sort of over-heating activity of a battery pack i would recommend you to place the pack (or cells) into a strong case or container such as a transmitter case and then remove them from the pitt area.

The pack had only been chagred at 6 volts and with a heat sensor, the pack must have shorted out some way?

wow,
thats scary :eek:
and i thought that we only had to worry about the new lipo cells desintergrating :(
thanks for the heads up and will pay closer attention to them in the future :)

Yeah this happened at the Off-road Nats this year. Someone finished charging a pack and put it back in his battery box, a couple of minutes later it started smoking and then at least one cell blew.

Here are some pics:
http://www.rcracephotos.com/displayi...album=7&pos=44
http://www.rcracephotos.com/displayi...album=7&pos=46
http://www.rcracephotos.com/displayi...album=7&pos=42

As for putting them in a box, you can do it, but I think its just one of those rare things that happens. I won't be changing my charging habits because of it.

Not to mention scaring the crap out of everyone in the building and the Drivers on the stand waiting to start the A main.....

IMO It is scary...make me think Nitro might be safer.

Just ask z-mann about them, he is the SMA expert at exploding cells......:lol:

:lol: :lol: :lol: :lol: :lol: :lol: I was there on both ocassions and my ears are still ringing.

Temperature guages are a must when charging, also more and more racers tend to recharge packs without giving them time to cool down after a heat or discharging. Also, some people set their peak delay too high to avoid false peaking.

I think we need a few hard facts about this incident.

How many times was it repeaked trying to find some heat ?
What type of charger was being used ?
What was the peak cutout set at ?

I've heard a few stories in answer to these questions which throw a bit of doubt on the statement that started this thread.

QUOTE "The pack had only been chagred at 6 volts and with a heat sensor, the pack must have shorted out some way?" UNQUOTE

Presuming that should be 6 amps not volts - what temp was the "heat sensor" cut out set at ?

It's important that we have all the FACTS !

Sorry Heavy about the amps/volts thing, all i know is that it had a heat sensor on it while charging and that it had been charged at 6 AMPS when fully charged it was put in a battery tray. Not sure if it had been repeaked or anything. I just want to let people know if you see batteries act like this, to take immediate action, from this experiance.

Heavy
4200 Worlds cell on a muchmore cellmaster set at 6 amps. Battery was peak charged with no temp sensor. cut of set @ 18mv. I think sonny charged it in a corally Battery box second slot in. The cell was disconnected then another cell placed on charge in the outside slot. The heat from this cell may have transfered to the problem cell. the pack overheated and was removed from the box in bits. one cell was so hot it started to melt the PVC table.

Sonny was a very lucky guy as the positive cap shot out putting a hole in
a oil bottle before hitting the back wall.

If it was pointing at him it would of hit him in the chest.

I'm not trying to question anything Shayne or Nigel are saying just trying to get the facts. i think we are all getting a little too casual about our battery charging - what we are setting the cut off at - how many times we are re-peaking etc etc.

For example if it was charged on a Much More then the cut off should have been set at 03 not 18

I need to get on to Sony and find out exactly what he did so we can make sure people are aware of how to avoid these kind of problems before people get hurt. This is on the eve of Lipo being available to the general RC public which have much more potential for problems.

lets get the facts out and have a re-look at what we are all doing - right or wrong.

If you don't think it's serious have a look at the photo below and imagine if that was a vulnerable part of your body

Fromr the Feral site
"Feral batteries have been packaged with a small amount of charge left in the battery. This helps to maintain the cells before use. After assembling the pack and before the first charge it is recommended to put about 200 seconds of charge into the pack and then discharge down to 0.9 volts. This will help activate the cells and possibly avoid any venting on the first charge

The new generation NiMh cells have similar characteristics as far as the charge technique is concerned. You should use the following settings:

6 amp charge for best voltage
3 or 4 mv cutoff per cell (18-24 mv per pack)
It is essential that you have a good quality charger. You have good cells so why destroy them with poor quality chargers"

6 x 3mv = 18mv per pack ??

At SMA theres a member whos had a few packs blow up, the best part is knowing when one is going to blow and then seeing it blow!! :nod:

Not to be mean but it is halarious to see what carnage follows eg. it blew in a mini once the body landed on race control :lol: and i had a cell casing land on my table. Another one blowing and then after being remove another cell hissing and smoking then BANG! i have pics on my phone of the burn marks on the bricks!!!

I think some people just need to take care of their packs better, when my packs vent i don't touch them, it just seems too dangerous to me!!

Although that being said is it a specific type of cell? My dad brought 2 4200 fantom packs for a challenge cup and probably not even 6 months after both packs had venting cells!!

Swamp Rat .... Heavy is asking whether the Much More charger was set at 3 or 18 on the charger as the charger has cutoff displayed for single cell which means you put in 3 mv in the setup which equates to 18mv per pack. If you put in 18mv on the setting you were using 78mv per pack which would explode the cells.

It is vital that racers understand their battery chargers settings. I have asked a lot of guys numerous times what settings they are using to only be replied to with blank faces !!!!!!! Learn whether your charger displays voltage cutoff as a single cell or pack measurement and set accordingly ....3mv per cell or 18 mv per pack.

Also be careful of repeaking as stated before with a long lockout. Most packs will repeak successfully in around 4 minutes If you have a 10 minute lockout set on your charger, it will continue to charge despite the voltage drop....the result can be a bomb !!!!!!!!

Can we have some feed back from the battery guys . Ferel / Harris

i have four sets of 4200 (2 of them worlds)1 from harris and 1 from ferel

they are both charging hotter than the standard 4200's

why is this ??