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Old 09-17-2007, 09:26 AM   #46
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Can we PLEASE have a thread about NIMH without all the lipo people ruining it? Keep it on topic.
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Old 09-17-2007, 09:26 AM   #47
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Quote:
Originally Posted by imprsme View Post
Hey note that when a certain drivers personal full size car went up in flames last year from the LIPO...he had not raced in a few hours and was in his house asleep.
Just so your facts are straight. Damaged pack left on car seat.
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Old 09-17-2007, 09:30 AM   #48
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I agree on safty tips.. just not how some threads present themselves...

ALL Batteries have to be followed and handled with caution< always read directions and ask a local elder racer for advice of any question you may have....
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Old 09-17-2007, 09:32 AM   #49
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Originally Posted by gndprx View Post
...On an ICE, I have the temp cutoff set at 120. The charger does what it's supposed to and stops charging at 120, however if you watch the temp after the charge is complete, I've seen it continue to rise by as much as 10-15 degress while just sitting on the bench disconnected from the charger.
The core of the battery is where the highest temperature is generated while charging a cell. The temp probe you are using with the Ice charger is only measuring the skin of the cell. This is why people aim to have a skin temp of 120. Thermal conductivity will allow the higher temp in the center of the cell to radiate out as the cell starts to cool. With that said, the core temp of the cell is probably more in the order of 140 F at full peak. This is why NOT to temp charge a pack sitting in front of a fan. The skin of the cell will be much lower, thus allowing the core to gain that much more heat, thus build more pressure.

In 15 years of racing I have yet to blow a cell (knock on wood). I am not saying that what I do with my cells doesn't have the ability to blow up packs, as I am known to charge packs at 8+ amps from time to time. I do, however, believe that it is how the cells are maintained that will determine how they will react to the abuse you subject them to.

As for the technologies involved, take your pick, flying particles, or a roman candle spewing napalm. They are both dangerous. I am sticking to what is legal for racing. Performance-wise, I will keep my Nimh batteries as long as they are legal and there is a performance advantage.
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Old 09-17-2007, 09:52 AM   #50
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Quote:
Originally Posted by John Tag View Post
What racing in all fourms needs is people posting the positive things being seen.. No all the negitive like in here. In any sport hobby there are dangers. To help the hobby grow expose the good not the bad expecially if you DONT KNOW all the facts of what really happened..
This is the same John Tag telling us one thing but doing in another forum what he is telling us not to do????

Quote:
Originally Posted by John Tag from CarolinasRC Forum
Topic: Link to Lipo fire

Guys please be careful with those packs.. A well know racer was doing some R&D with a major company and this happened..



http://www.rctech.net/forum/showthread.php?t=122084
I quess it is only negative against a product if one is selling that product???
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Old 09-17-2007, 10:06 AM   #51
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Here is an interesting story by Matt Higgins of RC Car Action Magazine!

Quote:
Originally Posted by Matt Higgins
LiPos seem to get all the bad press, but any battery can cause problems if not charged properly. I learned this lesson first hand today. I have well over 20 years experience in RC and have charged hundreds and hundreds of packs. I've never had a problem with LiPos, NiMH or NiCad packs--ever. Today I was charging a 7-cell NiMH pack for an airplane. I was using a high-end peak detention charger and set the battery on a metal surface. I did make one huge mistake. I left to go buy some new batteries for a transmitter. I was going right around the corner. I was goner about 15 minutes. Now, I fully admit I leave charging packs unattended all the time. As far as I can remember, this is the first time I actually left the house. When I came back, my garage was full of smoke. The battery had shorted and torched a mini I had a few inches away on fire. The fire blew out with two puffs, but it made a mess; the fire filled my garage with the worst smelling smoke and covered a lot of the surrounding area with nasty soot, ruined two packs and turned a brand new brushless-equipped mini into a pile of melted plastic and rubber. All said, it might sound pretty minor, but if I hadn't returned when I did, the fire could have gotten much worse. It was good way to start a house fire. I just got lucky.

I learned my lesson. I will never do that again. Now, I won't sit and stare at my packs as they charge, but my garage-based workshop now sports a fire/smoke detector and a fire extinguisher. I also won't leave my cordless drills plugged in to their chargers or any of the other bad habits I have.

My point with this story is that no matter who you are and how much you think you know, don't ignore the common sense safety practices like I did.
Good Advice!
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Old 09-17-2007, 10:10 AM   #52
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It wont put me off r/c, bad things can happen in any hobby.

Even having a set of IB4200wc cells go up in flames on me on a normal peak charge doesnt meen I will start telling guys not to buy them, they were working fine for every charge I had them until then.

Plenty of people can speculate on bad things on cell charging, but do you hear of endless posts of when a charge has been fine and people have praised cells??????

Thought not.
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Old 09-17-2007, 10:21 AM   #53
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This chap in the UK had some 4200s blow up!



The shratnel it throws when it blew stuck in the ceiling.



The story he wrote about it.

Quote:
Pulled from a UK forum:

Exploding IB4200's

--------------------------------------------------------------------------------

Luckily he was in a different room when there was a very loud bang. He went to have a look and found the pack split into many pieces and black dust everywhere. Some cells looked normal, some had puffed out and leaked goo, one (in the centre of the pic) has opened put with no sign of the contents, and one is MIA!

It smashed a battery box 30cm away, damaged a microwave on the other side of the room, 1 cell burnt through the floor, 1 positive button burnt through a cloth on the other side of the room, there are lots of mesh like bits stuck in the ceiling as seen in the 2nd pic, and black stuff everywhere.

They were charged as normal, 6amps 15mv for the pack, there were on from equalised for about 30 mins.

I have heard far to many things about exploding 42's
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Old 09-17-2007, 10:49 AM   #54
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Quote:
Originally Posted by ProTruck View Post



What is sad is the last video is not even of a li-po but a electronic speed control burning up that was hooked to a nickel battery pack!
Did you notice that the last video wasn't with the first two!!!!

The last one was posted to show how STUPID some ppl are! The guy reached in and grabbed something that was on fire and holds it up to "See" what was happening!

I posted that with the Title "this is not what to do"...
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Old 09-17-2007, 11:12 AM   #55
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Quote:
RC racing really needs some solid leadership and somebody needs to determine what is safe and what's not.
I think it's the people's actions that determine what is safe and what isn't. Anybody can make any kind of battery explode if he wanted too, but MOST of us are intelligent hobbyists that make smart decisions about charging rates and so on. I do agree that battery manufacturers these days are packin in too many amps into their cells, and they have not done thorough enough research about how they react to different variables (charge rate, ambient temp, physical cell damage, soldering quality, etc). However, this should not deter us from purchasing these revolutionary new products. I have two IBWC 4200 packs and have trouble with keeping them cool while I charge them. I do place the pack over a turbo fan when I charge them at 5.0A, and they still get really warm. With higher capacity comes higher charge times, but most people just crank up the amps to compensate. I think this is a bad idea. If you are worried about not having your pack peaked by the time you need to race, simply buy another pack so that you will always have a fresh one. I generally only take my two 4200 packs with me to the races, but I have found now that I probably either need to get a third pack, or switch to lipo.

This type of thread may be "informative and spreading awareness", but I personally think it's having a less desireable affect. Just like people have said about terrorism, the FUD associated with batteries exploding and catching fire now is bad news. Less people are using public transportation and flying these days fearful of terrorism, yet their chance of being involved in a terrorist attack is extremely slim. The same goes here: if you only trust your intuition and experience, you will know what kind of procedures are safe for using your cells.
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Old 09-17-2007, 11:32 AM   #56
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Quote:
Originally Posted by imprsme View Post
Hey note that when a certain drivers personal full size car went up in flames last year from the LIPO...he had not raced in a few hours and was in his house asleep.
AFTER that "certain driver" admitted that he:

1) Had a faulty charger that was not compatible, it over-charged the battery and it puffed up.

2) Waited until it was cooled down and then DISCHARGED the damaged pack, making it very hot again.

3) Threw it on the front seat of his car (while damaged, puffed and hot), then drove home, left it in the car and went inside.

I would say that those self-declared facts make it 100% operator error. Who's that comedian with the line..."You can't fix stupid."?
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Old 09-17-2007, 11:38 AM   #57
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Quote:
Originally Posted by Turbo Joe View Post
AFTER that "certain driver" admitted that he:

1) Had a faulty charger that was not compatible, it over-charged the battery and it puffed up.

2) Waited until it was cooled down and then DISCHARGED the damaged pack, making it very hot again.

3) Threw it on the front seat of his car (while damaged, puffed and hot), then drove home, left it in the car and went inside.

I would say that those self-declared facts make it 100% operator error. Who's that comedian with the line..."You can't fix stupid."?

Thanks for helping with my point....if that happened to a VERY seasoned racer. What is lil' joe racer gonna do with them???
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Old 09-17-2007, 12:35 PM   #58
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Quote:
Originally Posted by imprsme View Post
Thanks for helping with my point....if that happened to a VERY seasoned racer. What is lil' joe racer gonna do with them???
I think the point is more like seasoned drivers are not the best to look up to in terms of battery safety NiMH or Lipo. This thread was just discussing how high of an amp rate they charge their nimh. Do you really think that that attitude goes hand in hand with battery safety?

I think "lil' joe racer" is more likely to read the manual (RTFM).
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Old 09-17-2007, 12:46 PM   #59
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Really makes you wonder with all this info about 4000+ mah ni-mh if the battery cell manufacturers have gone too far for the sake of safety by packing those cells with too much capacity for the size of cell and also not allowing for the abuse RC cars/trucks/buggies present to them with them packed so tightly.
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Old 09-17-2007, 12:54 PM   #60
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Even if I do everything right with my own batteries, the guy next to me might not and his blows up and shrapnel heads my way. We are packed really tight in the pits. Why not use batteries that are safe rather than keep pushing the limits? It really comes down to driving afterall.

Quote:
Originally Posted by macnkitty2002 View Post
I think it's the people's actions that determine what is safe and what isn't. Anybody can make any kind of battery explode if he wanted too, but MOST of us are intelligent hobbyists that make smart decisions about charging rates and so on. I do agree that battery manufacturers these days are packin in too many amps into their cells, and they have not done thorough enough research about how they react to different variables (charge rate, ambient temp, physical cell damage, soldering quality, etc). However, this should not deter us from purchasing these revolutionary new products. I have two IBWC 4200 packs and have trouble with keeping them cool while I charge them. I do place the pack over a turbo fan when I charge them at 5.0A, and they still get really warm. With higher capacity comes higher charge times, but most people just crank up the amps to compensate. I think this is a bad idea. If you are worried about not having your pack peaked by the time you need to race, simply buy another pack so that you will always have a fresh one. I generally only take my two 4200 packs with me to the races, but I have found now that I probably either need to get a third pack, or switch to lipo.

This type of thread may be "informative and spreading awareness", but I personally think it's having a less desireable affect. Just like people have said about terrorism, the FUD associated with batteries exploding and catching fire now is bad news. Less people are using public transportation and flying these days fearful of terrorism, yet their chance of being involved in a terrorist attack is extremely slim. The same goes here: if you only trust your intuition and experience, you will know what kind of procedures are safe for using your cells.
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