Sweden bans latest batch of IB4200

[DCM]

that would be very awkward for nimh's especialy those in a saddle pack configuration

[mark christopher]

Originally Posted by kyosho-viking

you looking for something like this??
http://www.b-p-p.com/proddetail.php?prod=1_BB&cat=15

but they are expolding in cars on the track too, so that wont fix the problem, chances are they will go as you take em out

[millzy]

Originally Posted by DCM

right, txt speech, it does not potray your exact intent on what you mean, and really, it maybe one or two key strokes to spell the whole word, so spell it. Coming from an engineering background, really gripes me seeing people abusing the english language.

.

see old ppl

Originally Posted by super__dan

Or the ones getting old before their time (puts hand in the air).

dan, it was you i was thinking of as i posted that

[kyosho-viking]

Originally Posted by mark christopher

but they are expolding in cars on the track too, so that wont fix the problem, chances are they will go as you take em out

charge em and leave them for ten minutes after they are finished. The reason they blow up at track, is that the driver charges them in the car, repeaking and then racing, can be a couple of minutes before they blow.

[DCM]

chris, txt speak has it's place, but when you are trying to convey a point across, thats just not the place.... I will admit, i hate the stuff and wish it gone, txt speak I mean.

[mark christopher]

Originally Posted by kyosho-viking

charge em and leave them for ten minutes after they are finished. The reason they blow up at track, is that the driver charges them in the car, repeaking and then racing, can be a couple of minutes before they blow.

how can you claim that and do you have proof?

[DCM]

I would agree that fully charging a pack of batteries, and then re-peaking them shortly after is going to raise the internal temp and probably pressure of the cell. But i think KV is stretching the facts just a little.

[kyosho-viking]

Originally Posted by DCM

I would agree that fully charging a pack of batteries, and then re-peaking them shortly after is going to raise the internal temp and probably pressure of the cell. But i think KV is stretching the facts just a little.

read your charging manuals guys, are you supposed to re-peak shortly after full charge cut-off?? Are you supposed to charge with more than 1C??

The incidents in Norway happened after charge whith 6amp and too high delta-peak. still the federation ban racing.


What do you think happens?? when driving, the cells get hot, yes. But the pressure are reducing, so if you have another theori, I would be glad to hear it.

[DCM]

I just think the cells that EP and IB are producing are right on the limit of performance and basicaly some survive, some don't, I am guessing that after one certain batch where they were getting loads of duds in a batch, the ones that got through were marginal too.

[SlowOne]

If the cells are exploding (and they are) then that takes a lot of energy. Is this a viable theory...?

If it takes a lot of energy, then that has to be built up somewhere. If it were to build up slowly, then the can would distort badly first, before splitting. If that build-up were a gas, it would vent in the majority of cases through the top, or peel the cell apart at it's weakest point - probably where the lid is folded into the can. My theory is that it is not a build-up of gas that leads to the failure. If teh build up were expansion of the chemical, then the can would split, and the chemcial would spurt out, and that would be the end of the incident.

If the build-up of energy is very sudden, then the cell will fail catastrophically. The main source of a sudden pressure change would be the direct conversion of the energy in the cell, and that would come from a direct connection of positive to negative - a short-circuit. That suggests that the construction of the cell is failing quickly. The main stress put on that structure is during charging and discharging, and the higher the charge rate, the more the stress. Since we have reports of this happening during, or shortly after, charging, then it suggests to me that the charge rate, and charge condition (balance of the cells, and overcharging due to imbalance of cells at peak) is likely to be the cause of stress. My theory is that the cause of the failure is in the internal structure.

Supporting evidence is that the cells have been stretched to the maximum over the years by changes to internal structure. Those who use 1C to 1.2C charge rates, and that those who balance cells before charging at this rate, have less problems with cell performance - they go much longer before the performance goes off. Most of the reports of incidents talk about re-peaking and/or high charge rates. Also, this is not unknown from the past, and those failures would be consistent with an internal structure failure.

My theory is that the internal structure is weaker than lower capacity cells, that the charging regime is damaging that internal structure, and that the failures are from a very rapid build-up of energy arising from an internal structure failure (short-circuit) releasing large amounts of energy capable of splitting the can catastrophically.

Discuss...

[kyosho-viking]

norwegian cell afterwards

http://forum.radiostyrt.no/vb/attach...4&d=1194344055
http://forum.radiostyrt.no/vb/attach...3&d=1194344044
http://forum.radiostyrt.no/vb/attach...5&d=1194344064

[mark christopher]

Originally Posted by kyosho-viking

read your charging manuals guys, are you supposed to re-peak shortly after full charge cut-off?? Are you supposed to charge with more than 1C??

The incidents in Norway happened after charge whith 6amp and too high delta-peak. still the federation ban racing.


What do you think happens?? when driving, the cells get hot, yes. But the pressure are reducing, so if you have another theori, I would be glad to hear it.

my manual for my charger does not say 1c, however the manufacture ib recomends 1c

[kyosho-viking]

Originally Posted by mark christopher

my manual for my charger does not say 1c, however the manufacture ib recomends 1c

well, excuse me, you understood what I ment.