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Old 04-13-2008, 03:41 PM   #1
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Default Exploding batteries

Gday,

This thread is not to turn into a debate about nimh vs. lipo etc.

I wanted to know if there is a way of testing that a cell is about to go bad...

Would the internal resistance check pick this up?

This happened very close to me on the weekend, and it scared the hell out of me. So I'm trying to find a way to maybe prevent this in the future.

I beleive the battery was being charged correctly, 5amps...

Any ideas to make this hobby safer would do us all good.
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Old 04-13-2008, 05:25 PM   #2
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Ashley,
The only reliable indicator I know of is cell temp. The reason the cells explode is the expansion of gas inside the cell. I always watch my cells when charging and if one is coming off notably hotter than the others I'll take a close look at it as far as charge, discharge and balance. Hope that helps.
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Old 04-13-2008, 08:21 PM   #3
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Thanks for your input,

I guess what I was looking for is maybe a way a club can check someones batteries before they race... but I guess that probably isn't really feasible...

Maybe there isn't a solution? All I know is I was real close to where the battery went off and it scared me into trying to find a solution.
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Old 04-13-2008, 08:40 PM   #4
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Was it Lipo or NIMH?

Did the battery cook on the charger or coming off the track? To have a club check a battery before or after a race is a little harder than you would think. If you check it before the race, racers will get mad due to taking off the top charge if NIMH. You really can't check it afterwards due to possibility of being too late.
Also NIMH's are hard to test at a basic level for resistance. Unless you are charging by the cell and not by the pack you will never know until its too late. Like Thugs said, proper care of either Lipo or NIMH is important. Granted you can watch your own packs but the racer next to you might not be as careful. Hence, why you should always be aware of whats going on next to your pit. I have seen many NIMHs in my days go up in smoke. Still venturing this new lipo era though.
Electronics are kind of tricky to diagnose problems until the problem occurs. All you can do is follow proper guidelines for charging, discharging and balancing.
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Old 04-13-2008, 09:19 PM   #5
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it was a ib4200wc cell
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Old 04-13-2008, 09:39 PM   #6
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IB4200 are known for their explosive power

I would not be going anywhere near any IB4200 cells. The newer IB4600 is supposed to be better
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Old 04-13-2008, 11:02 PM   #7
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While charging at 5 amps would seem like the perfect setting to keep batteries from popping the positive caps off, that is entirely a myth that too high an amp rate will pop off the ends. The important numbers that you should be paying attention to is the delta peak number. During the summer I have the setting at 3mv/cell. In the winter I usually bring that up to 5mv/cell, this allows a little more heat in the cell (reduces internal resistance). On my Ice, I also use the temperature probe set to 120 deg. f.

I have yet to pop a cell. I normally charge my packs at 7.5 amps or greater. I don't run lock-out. I don't get false peaks.

YMMV
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Old 04-14-2008, 01:29 AM   #8
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it's almost certainly because one of the cells had self discharged to 0 volts and wasn't detected before being put on charge.

the ib4200's are unstable and can self discharge rapidly. you pretty much have to not only put a partial charge back into them, but monitor them during the week to make sure their voltage doesn’t drop too low.

some cells that have 0 volted can be revived; by charging the lone cell at 1.2 amps for 1 hour. if your charger keeps tripping you can charge across the pack for briefly to bring the bad cell's voltage up enough for your charger to see it, then isolate and charge the cell individually from there (as above). if the cells voltage doesn't come up quickly, it's dead.. don’t force the issue, remove the cell from the pack. once this has been done, equalise the cells back down to 0.9v and go from there.

please only attempt this if you know what you are doing and willing to monitor the cells temperature throughout the process. as noted above - if the cell starts heating up, stop the charge, wait for it to cool down and then remove the cell.

this is only a temporary fix, cells that drop to 0v quickly will continue to do so and ideally should be removed from the pack.
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Old 04-14-2008, 06:50 AM   #9
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ib4200wc, I picked up two pack of them.
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Old 04-14-2008, 08:30 AM   #10
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Yesterday weekend meet was kinda fun with an ib4600 pack exploded during discharged with Spintec batman v2. Not sure why it exploded as the cell is not warm at all. Yes you got me right, is during discharge and not charging.

All I heard was a loud bang and a cell came off like a shotgun palette. Damn, this is getting scarier. Luckily no one was hurt.
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Old 04-14-2008, 10:43 AM   #11
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Default IB4200 issues.

Here is a post from our clubs forum, although it pertains to stick packs, if your not prepared to do proper cell maintanence with a sideXside pack, the same thing will happen. Now why packs are going in Spintec chargers, I have no idea, but I was beside one that did the same thing.


Stick packs are OK just not the IB4200 ones, most suspect in explosions and with the nature/proper maintanence of that particular cell, we already know that they will be the most prone to explosions.

Here is my thinking about them. We already know that the IB4200 has a massive self discharge issue and as such, in a stick pack you have no way to discharge individual cells. So with that, if you do a pack discharge, sure you will get the the packs intital voltage down to what ever your pre-determined cutoff voltage is, BUT, what if thats done because you have one cell thats going into a deep discharge and takes the rest of the packs voltage numbers down with it, and this can be done very easily. Now lets charge that pack, we have one cell starting at a very low voltage, and say 3 cells and normal float voltage, and 2 cells that seem to hang on to the voltage for a long time. Begin charging, low cell chugging away, 3 cells excepting normal charge, and our 2 cells that are not even close to the .90 volts but are sitting at 1.1 volts or something like that. Okay, 40 minutes goes by, the bad cell is still taking a charge, the 3 cells are getting close to peaking and those other 2 cells, well they where done about 10 minutes ago, but the actual pack voltage isn't anywhere near shutting off your charger as your pre-set over charge hasn't triggered yet. SO whats left, just the bang.

Stick packs in general get the low end cells to begin with so they are more suspect to failure, IB4200's are the most notorious for low shelf life. Stick packs are usually purchased by beginners, so they have very little battery knowledge. Little battery knowledge/High maintanence cells = ONE BIG EXPLOSION.

***** This can also apply to saddle packs if not properly discharged and charged, but these cells are individually accessible and you can at least make an attempt to cycle the individual cells, where a stick pack is usually wrap and no single cell access is available.

Now lets take this one step farther, how many pre-built IB4200 stick packs are sitting at the hobby shop right now? How many have dead cells sitting in those packs? How often has the hobby shop been cycling the packs? once a month? once every 2 months? I think not. So in our best interest if a newbie wants to buy a stick pack, for safety sake, keep them away from the IB4200 stick packs.
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Old 04-14-2008, 09:48 PM   #12
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I noticed something weird last week during charging of a 6 cell IB4200 matched pack. This pack has never peaked at higher than 9.23v but during charging pre-race I noticed it went up to around 9.5-9.6v

One of the cells in this pack exploded after the race.

What I'm wondering is, would the higher than usual peak voltage during charge been a sign that one of the cells was in a bad way?

Last edited by mok; 04-14-2008 at 10:14 PM.
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Old 04-14-2008, 11:06 PM   #13
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Quote:
Originally Posted by Ashley Cobb View Post
Gday,

This thread is not to turn into a debate about nimh vs. lipo etc.

I wanted to know if there is a way of testing that a cell is about to go bad...

Would the internal resistance check pick this up?

This happened very close to me on the weekend, and it scared the hell out of me. So I'm trying to find a way to maybe prevent this in the future.

I beleive the battery was being charged correctly, 5amps...

Any ideas to make this hobby safer would do us all good.
Ashley
is this all the info that you have,
Has the guy owned the cells from new or are they second hand , if so how much abuse have they had.
what charger was being used , if it was a lipo based charger bid he have a temp probe on the cells.
have the cells been equallized.
what was the delta peak setting.
its easy for people to blame the cells when they dont follow the correct procedures.
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Old 04-14-2008, 11:18 PM   #14
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Quote:
Originally Posted by cannon View Post
IB4200 are known for their explosive power

I would not be going anywhere near any IB4200 cells. The newer IB4600 is supposed to be better
Cannon
you as a battery matcher should know the consequences of wrong treatment of batteries , have a think back about 6 months ago to what you put on rc racer.
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Old 04-15-2008, 03:12 PM   #15
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I figured this would be as good a place as any to post this. At our club race this past weekend, a fellow racer who has three of his sons racing with him, had a 6 cell pack explode inside the case they were stored in. One cell exploded, but I believe others were to follow shortly. The situation here was he had to charge his and his sons packs ahead of time, earlier in the race day to be able to keep up with the time needed wrenching on cars. After they were charged, he put them back in his "black fabric" zipper case. The temp Sunday was at least in the mid 90's. Now the temp of cells, even with a 3mv cutoff, is hotter in hot weather. I'd say these 3 to 5 packs were sitting in the late moring direct sunlight (had canopy up, sun not directly overhead yet) inside the black case for at couple of hours. Luckily the cover kept his youngest from getting seriously hurt. He threw the case onto the offroad track next to the paved one we were racing on. When I got up the [email protected] to go look at the rest of the cells, the shrink wrap on almost all of them had split and were VERY hot!!!
Out of all the precautions we've learned to take while charging and storing these cells.. here is a nother example of what we need to be careful of. These could have been inside the rear window of a car and exploded on the way home from the track! FYI fellow racers...
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