MAD916

Hey guys as the title says we had one of our NW series club race yesterday. Friday night we had some guys practicing before the event. Our victim had run the pack once when he got here it seemed flat so he put on c MM cell Master and dicharged at 10amps.........

probaly 15 minutes into it... the end cell blew its top... not the whole cell but went off like a firecraker.... and scared the hell out of us...

It was not a complete cell explosion like I had in Vegas this year with my new 4200, (yeah that was me) this only blew the top off....

but what the hell?????? a 10 amp discharge??? any thoughts on this one.


TZR

Steve Bahnatka

iTrader: (5)

Can we have some pictures?

Danny/SMC

iTrader: (2)

That cell must of shorted out internally. We have cycled 20 000 or so cells and so far we have seen 4 cells that have popped off the positive cap which to me is better than a full blown explosion like we have seen in the past. All new generation NiMh have super high performance and are relatively using the same materials and craftsmanship.

EddieO

iTrader: (6)

As with any battery, yer gonna see some blow up........the Energ is not immune, just way less likely than the IB's were.......I've been racing for 20 years......I have seen every type of cell go boom....1200, 1400, 1700, 2000, 2400, 3000, 3300, 3700, 3800, 4200......all have gone boom at one time other another for various reason......I have even seen transmitter batteries blow up....

Later EddieO

tyreguy

iTrader: (148)

First person to post a problem with these cells... With the number on teh market that is pretty good!

bboy

What is the best way to prevent cell blow ups? Is temperature probe the way to go?

I am really worried that one of these cells will blow up in my face one day ...

wallyedmonds

i dono but iv never had a cell ib sanyo panasonic or ener-g blow up on me before.
guess these things now are just touchy

but i do charge and discharge way away from me in a spot that i think wont hurt me if one go's.

convikt

iTrader: (27)

good thing I run lipo only now.

We knew this was going to happen sooner or later with the E's

........its like eating to much and you puke,
what does everyone expect

yyhayyim

iTrader: (26)

I cant belive tracks and sactioning bodies are not doing more to protect people from these packs...what;s it gonna take? Someone's eye getting dammaged by one these explosions? Look at what happened to Gilles at the DHI cup!! Scarey stuff...what can be done to make them safer?

redbones

Lipo is supposedly made of nitro glycerin and banned at the property we race at. Some f**ktard told the property owner that lipo are like gun powder and prohibited it from running there. We tried to convince its safety, but his mind set would not change...

Wild Cherry

How much longer before someone is injured by one of these Nk-Ml pack explosions ?
Hopefully politics does not decide how long ...

Common knowledge there is a serious problem , yet there are only rules for Li-Po safety .....


Who`s going to explain to the first person who loses a eye why they still have no safety rules safeguarding us from these dangerous battery`s at the races ?


It will happen , only a matter of time .....

flameoutgarrett

iTrader: (10)

my #1 rule for before charging a nimh pack

Check each cell with a voltmeter, i have yet to blow a cell, it helps me sleep at night

if i come across a flat pack i try to find the problem, if i cant then it will go into my pitbox and stay there

Ray Lan

iTrader: (4)

I started R/C using 1700 cells.
Today, 12 years later, the same sub-c package holds 4600, 2.7 times the capacity.

Well, being an engineer myself, the laws of physics don't change with time... We may well be at the limit of sub-c technology, until another material technology breakthrough. No surprise that the cells are getting more volatile, the line between performance and safety have gotten too thin.

Guess the only safe thing to do now is to not allow the cells to peak at 100%, reduce delta peak.... sounds stupid, but i guess thats the only way to ensure safety. A friend of mine sets the temp cut at 45 degC. I'm getting an Avionics for zero delta and li-po compatibility.

tfrahm

iTrader: (2)

I've come to the same conclusion... I just bought 3 packs (4-cell) of SMC Ener-G cells. I've had some minor self inflicted issues -- now I think I've found a ritual that will be as safe as possible.

Mostly I follow their suggestions. I race 13.5 Oval, and Danny has said that it is OK to just leave the charge in the pack if racing once a week... Then, before charging, discharge the pack to 3.60v (for 4 cells), equalize (I use a Novak Smart Tray set to 0.9v), then charge at 6 amps.

Where I deviate from the suggestions is on the Delta peak setting. SMC recommends 5mv per cell -- I set my charger for 3mv per cell. The pack still "peaks", but I have a much smaller "over charge". Remember that the cells Peak and the Delta we set is really a measure of how much to OVER charge the pack. I just reduce that. I can't see any difference in performance (and if my Physics training is correct I shouldn't -- "peaked" is still "peaked"...)...

Also (this is one of the "self-inflicted" problems I had) -- DOUBLE CHECK the equalizing if you use the Novak Smart Tray! More than once, I've had mine click off on a cell when that cell was NOT equalized. The logic in this tray is designed to discharge a cell down to 0.9v, then "release" the cell to rest on it's own. If ANYTHING causes the tray to think the cell has dropped voltage, the tray may stop prematurely on that cell. This can lead to the equalizing process actually CREATING an unbalanced pack! Before I pull a pack off the tray, I hit the start button one more time just to be "safe"...

I also monitor the cell's temp during charge -- no problems so except for once after a "bad" equalizing (one cell hit 155 at peak, the others were 100 or less). Now I see all 4 cells peak at similar temps (usually 125-135, and almost never above 140 -- 140 is SMC's stated "ideal" temp)...

Ray Lan

iTrader: (4)

Check out the graph on this page:
http://www.batteryuniversity.com/partone-11.htm

Observe the exponentially increasing PRESSURE and TEMPERATURE as nickel based batteries near 100% charge. scary stuff.

Also... some part of me feels that IB may have changed their marketing "face" by rebranding. So... it may still be the same batch of cells which blewup in recent times.

Race safe fellow hobbists.