EP 4200 blew up in my face today.
 

I had bought two new trinity matched EP 4200 packs and started building them today. I discharged all the cells to 0.90 volts and began soldering the bars on. Half way done soldering the pack I had my iron on one of the cells for about three seconds. After that things went fast, but I remember an extremely loud bang coupled with a burning sensation on the upper part of my face. I washed all the acid off my face and flushed my eyes. Long story short my vision was blured for hours, I have tiny pieces of metal imbedded into my skin, hopefully not my eyes, and was in pain for quite a while. I am still trying to contact trinity, thier office must be closed. It was a frightening experience. I have been an electric enthusiast for a long time. With the recent talk about batteries exploding, catching fire, and un-reliability being more common, NiMh and Li-Po alike, this might be the end for electric with me. I very could have lost an eye from the cap blowing off the cell. I will not buy another product from trinity. If this pack was matched from them, how did it explode while being soldered? Stories of EP's failng is becoming more common also. These cells are thought to be more durable but recent stories are telling the opposite. I thought this information should be put out for people to see. A fair warning, friendly advice, and a saftey precaution.

Thanks,
-RCRoads

Sounds like you might have shorted your iron against the top of the cell. Were you working on the positive side when it happened?

were the cells hot from being discharged?

a good lesson to be learned is to wear safety glasses....
batteries store potential energy and when things go wrong....
especially with the high output of amperage in todays cell technology
you cant assume anything......

Yes it was the positve side that I was soldering at the time. It is also the side that blew off. The negative side is severly bulged and was supported by the battery jig. There is no evidence of shorting. The shrink wrap and label around the cell still looks brand new. No burn marks what so ever. I even double shrinked wrapped these cells. Plus I had the iron on top of the battery bar making it even more difficult to short it. Even if it was a short, it would have to be shorted for much longer than the few seconds I had the iron on it before it blew. And yes the polarities were correct. There were about seven people in the general area at the hobby shop when it happened and no one noticed anything unusual about the pack.

The cells were at room temperature when I was building them.

Scary, looks like so dangerous in actual era to join RC.
Because mostly people told me to EP batteries, which are much reliable and less trouble than IB, but until now i must not to be so much confidence.
GP ones are the best, at least you must not to worry to blow.

I saw a NiMH Sub C explode at SoCal a couple of weeks ago. I'm not sure what happened. Went with a very loud bang and small pieces everywhere.

I never thought about it, but I'm wearing safety glasses from now on when soldering, charging or discharging. Scary stuff!:eek:

an intellect ib4200 went boom at a local race here last friday. i was walking away into the hobby shop and bang. straight up sounded like a gun shot.

crazy stuff. i think he was only charging at 6A. just got hot

that looks more like a pressure blow off than anything else, you didn't accidentaly block the vents in the cell?? Also, why are you guys double shrink wrappin, it just makes it harder for these cells to lose their heat.

Hope the injuries heal, I think Trinity need to at least carry out an investigation into this though.

could of had a bad cell. You might have had the iron on the cells to long. I have ran EP 4200's and never had an issue with blowing them up. Or you could of some how shorted the cell ur something.:confused:

I've noticed all the IB cells like to vent at the drop of a hat. They seem especially sensitive to high current coming in or going out. Great numbers, though.

Hold on, which generation EP is this one? M2 or M3, maybe the matched ones are still M2, isn't it?

they should just put a stop to battery development. they should of done it a year ago.

just say 3800mah and thats it, no more.

but no they said instead change to 5 cell rule

Whats that got to do with this problem. it don't matter if ROAR, BRCA, IFMAR jmrcA rule out any more higher cap cells, we are a minor market which the cells makers supply, do you really think they would listen? This sport is like any other, we will try to get the most out of a power source. Although I have found that you gain so very very little charging at 6A, i have dropped it back down to 5A, cells stay a little cooler to, and my IB42 cells are two years old.

as for the cell, i would guess, looking at the pics, the top part of the cell wasn't assembled correctly, as the rest of the cell seems undamaged, so it wasn't a dead short, just a build up of pressure inside the cell, and then the cap let go.

it matters coz when they try to cram more energy into the same size cell, they are pushing the limits more and more.

this sort of thing never happen to 3800 or 3300, but is common occurance nowadays...


the pic dont show user error to me. he even double wraped it, and its new anyway so the shrink wrap should of been intact anyway.

p.s so tell me what other markets use sub-C cells at 4200mah at 1.25v? i know of none.
in anycase if the cells were not legal then not many people would use them as matchers wouldnt be able to match them for big races and clubs wouldnt allow them and racers wouldnt buy them.