LiPo's Expanding after a run.

[Wee Han Loh]

Hi Guys,

Help! I need some advice from you guys experts. I'm having some problems with my Kokam Lipo's SLPB 834374H (15c Discharge type, 30 Amp) 3 series (11.1v)

After 3 runs (10mins) each i found the center piece expanding to almost double its size. I stopped immediately & cooled it down. Tried to charge the set it but wasn't able to, think the centre one is dead. Reading was 8.xx Volts then.

I don't know what went wrong cause my 2 set was fine & was not expanding at all. Hardware used was an XRay with U-Force 50 and Lmt 5300, ratio was 6.81 though. I don't know the amp draw for the setup.

Please advise, thank you.

Cheers..

[Craps]

I don't have any experience with the kokam li-pos, but it sounds like you over discharged it and caused the cells to be unbalanced. I have the U-Force 75 esc and I think the U-Force 50 is like it in the way you can PC program it to have the voltage cut out at 9 volts when using the 11.1 volt battery. The default is 5.5 volts the esc is set at and you to get the optional PC link cable and software to change this.

Contact the manufacturer and they may do a swap at 50% of cost for the battery. I know Thunder Power does this kind of thing due to my 1/8th scale buggy did about 4 batteries like this when I mismatched older and newer batteries together in series.

Good Luck!

[glassdoctor]

You don't want to use any cells that puff like that. It's toast and it can blow up on you if you continue to use it. The other two cells might be ok... but be careful with them.

Looks like you had maybe two problems... overdischarged like craps said. A 3s lipo should not be run down to less than 9 volts at rest.. after a run. (It can dip lower than 3.0 per cell while in use, but should come up to 3+ resting voltage.)

And possibly to much current for the pack.

But if you were getting 10 minutes per charge, that shouldn't stress a 15C rated pack... unless you are pulling well over 30 amps a lot of the time, with a lot of "dead" time making up the 10 minutes...

[Wee Han Loh]

Hi guys,

Thanks so much for the help. Guess both of you were right. overdischarging the centre piece. Was bashing around for fun & voltage dropped to 8.xx + volts just after it started to slow down. 10 mins was on straight runs only.

Brought it to the shop & they're replacing a new piece for me. Lucky it didn't explode. Time to shop for the pc link now for the auto cut off feature.

Thanks again, Cheers.. :)

[Craps]

It would not have exploded unless you charged it back up. I have yet to see one explode except videos on the net where people overcharged them on purpose to see them explode. They are tougher batteries than the nickel manufacturers want you to know.

[NitroBoy24]

Dejavu :D

http://www.helihobby.com/videos/LithiumBattery.wmv

Just found one of the videos craps was probablly referring to, they purposely, incorrectly charged a lipo pack to the point of it exploding. Pretty nutty stuff..

I received my Etec 2400, 2S pack for my Mini-quake (waiting for my Kokam Voltage cutoff to come in before I run it) so I am definitely going to be careful with the packs.

I'm glad you got some help and didn't mess with the packs :cool:
Good luck!

[Craps]

The famous video everybody refers to and tries to scare the crapp out of everybody that may be interested in buying Li-Pos. I have news for you all, you do can do the same thing to any battery including nickel batteries except with li-po you get warning in advance by it swelling and with nickel batteries in it's metal case there is no warning just a "pop" and you better hope none of the metal casing hit you like shratnel from a grenade. Don't you guys love the internet and how things can get blown way out of proportion, especially by the nickel battery manufacturers who want to keep there share of the RC market place. Some how these pro nickel battery companies are usually the same ones trying to keep brushless motors out of racing too.

Guys don't think I am getting comfortable with using li-pos, like any battery you use please follow the manufacturers instructions to handling and charging them and please use the correct charger for what ever type of battery you use!

I also find it real funny how in the "New Products Forum" they are going ga ga over some 3700 nickel cells when you can buy an 8000 mah li-po pack that is the same size and voltage as 6 nickel cells that is 5 ozs lighter.

[glassdoctor]

I agree that there's a lot of lipo scare factor on the internet.

But I think that's a good thing actually. It didn't stop me from getting some myself, but it did make me aware of the dangers... so I know how to protect my property and family. I will just be more careful, and I understand what CAN happen if I get careless.

If you learn to proper ways to handle lipos you should not have any tragic events.

Optimaman can confirm that lipos ARE more dangerous than other batteries. I've never heard of anyone burning down their house using nicds... even though you can blow them up if you intentionally abuse them. I've neve seen it personally.

[Chase023]

I guess you know by now with all the comments and advise that you should have a Voltage cutoff on your controller if you are going to use Li-polys.

Remember there always is a fear of the unknown. Basic Human Trait. (Not always good)

I use lipos on my M18 and it runs great. With proper care and responsibility, they are awesome.

I hope to replace some of my other GP3300 with Lipos if I can.
By the way the AstroFlight 109 is a good charger IMO.

[Craps]

Optimaman can confirm that lipos ARE more dangerous than other batteries. I've never heard of anyone burning down their house using nicds... even though you can blow them up if you intentionally abuse them. I've neve seen it personally.

Maybe I missed something about his house fire, but I never heard it came from li-pos and in fact I thought he was charging nickel batteries that was being charged unattended that is a "no no" with any kind of battery.

Maybe he will post here and clear this up because I thought he was using 3 chargers at the same time and did not know which one started the fire.

Be safe with any kind of battery!

[OptimaMan]

Actually, when I was a kid, I almost burned my house down with NiCads!!!! I was charging my 1200 mah SCR 6 cell. I made my own homemade 4 minute charger - I would charge my batteries at 20 amps - but it didn't have any failsafe or anything. So, I plugged it in and forgot about it. 10 minutes later, I heard a very loud explosion and tons of nicad smoke in my bedroom. Super hot schrapnel flew all over my room burning my chair, my scalp. Nothing actually flashed, but if there was something flammable nearby, could've easily burned.

[glassdoctor]

Yeah, there was several chargers going, including lipos... correct? I think it's a pretty safe bet that lipos did it. In a matter of minutes, what else could create such a fire?

Nicds have been known to explode, but they don't flame like lipos. I've never had a nickel cell explode yet... and I have abused quite a few over the years, such as when a charger malfunctioned and never stopped charging. I noticed a smell, and saw the charger was still going... about a half hour after it should have peaked. The pack was way to hot to touch... all the shrink melted etc. But no bang, no fire. Lipos would be a big problem if that same thing happened. That's the only difference. IF something goes wrong, you have a bigger issue... more damage likely.

Nice story of the Nicds, Optima... you think 20 amps might be too much? :) Reminds me of when I went to a friends house as a kid and he had some Duracell "D" cells that were going dead. So he took his automotive batery charger, like a 10-50A model, and held the clamps to the alkalines briefly. He said it would put some charge back in them. I thought he was nuts... sparks and all. Anyway...

I doubt you had any nickel packs charging at 20A when the fire happened. Again... highly unlikey that nickels were at fault.

I'm sure a bic lighters and cancer sticks are responsible for many many houses burning down, etc... and every time it's "user error" that does it. I'm not bashing lipos, just being realistic. Keep them in sight and away from flamables while you are charging, that's all.

[OptimaMan]

I did have NiMH get so hot, all the solder melted off them once last winter. I used to routinely charge my 2 6 cell 3300's in series with my Triton charger at 5 amps. For some reason, it didn't stop charging. Like I said, it got so hot, the cells started to vent badly and the the solder all melted off!!! Solder melts at close to 500 degrees F. Many plastics and paper actually can flash at below 500 degrees F!!! So, I wouldn't be so quick to say it was the LiPos.

During the fire, I actually had the 2 x 6 cell NiMH being charged at 5.0 amps with that same Triton charger and the batteries were on a plastic table! But, the 1900 mah lipo was being charged at 8 amps.... Probably the cause though. I haven't gotten the courage to actually go and buy those exact packs (TP 1900 mah packs) again and charge it at 8 amps... Maybe one day I'll do that. Sigh... never want to relive those memories again.

[OptimaMan]

Hey Glassdoctor: are you an optometrist? BTW, when I used to charge those 1200 mah packs at 20 amps, I got a LOT of uses from those Nicads. Eventually, their internal resistance started to get kinda high. About 3 years ago, when I got back into the hobby, I actually raced my Optima Mid with an 11 turn motor and those old 1200 SCR packs and I could actually get 5 minute races against the 2wd mod buggies and keep up with the guys in the B-Mains!!! Actually, I had better acceleration by far - but the suspension has come a long way since the mid 80's so they all outhandled me in the turns.

[glassdoctor]

Those old Kyoshos were cool. My first car was an Ultima. I really wanted an Optima back then. The friend that charged Duracells had an original chain drive Optima back then.

The 1200 SCRs were the best in their day. But man they were expensive for matched packs. They would go for like $80-100 sometimes... as I recall.

No, I'm no eye doctor :) I work on auto glass... worked for myself for a dozen years now. So I do occasionally polish glass, but the big kind. Mosty I do windshield rock chip repair... one of the best anywhere too. ;) When I'm not on the r/c forums, I check out the glass forums to see if any new guys need help.

[OptimaMan]

My buddies first car was an Ultima and mine was an Optima Mid (the model right after the Optima). I did get a used Optima but found the Optima Mid to be a way more efficient drivetrain. As a matter of fact, the first "stealth" tranny. Had upper pinion, middle idler gear, and lower diff. Used to be 32 pitch though and I had the hardened MIP steel gears. Real noisy, but bulletproof!

[Craps]

I think the lesson learned here is do not charge any batteries in the house unattended no matter what kind of battery they are!

There was some pictures on this forum not to long ago that should some nickel batteries that exploded without warning and if the owner had not been wearing glasses it would put an eye out with the hot metal casing flying around.

ALL BATTERIES are dangerous if not handled and charged per the manufacturers instructions! Use the correct charger for the battery and do not charge them in the house unattended no matter what kind of battery they are! Do not let your guard down because you think nickel batteries are safe!

[mugenX5]

Glassdoctor: You don't happen to be a member of CustomTacos, do you? There is a member with the name Glassdoc on there and I thought maybe it was the same person.

[glassdoctor]

Nope... not that I know of anyway. :)

[Reinhard]

@Wee Han Loh:
maybe you should also go up in capacity with your lipo-cell..

i think you had 2000mAh-cells..

15C rated..
so only 30A...
hmm..

i use this one:
http://www.kraeuterbutter.at/Bilder2/XXX-4/ThunderPower3s2p.jpeg
Thunderpower 3s2p 4200mAh
weight: 288g without wood-protectors

42A contiously (50A contin. with cooling)
63A 5sec-peaks
75A for less than a second..

this is way enough in a light rc-car:
(3,3Volt on 50A ==> 500Watt and peaks up to 700Watt)

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

your cells are this one i guess:
http://www.elektromodellflug.de/akku-test/bilder/kokam-2000.GIF
hmmm....
infact: realy light your setup:
3s1p 52g each cell ----> 160g the pack...


maybe you wana ad a little weight...
and take this cell if they fit:
http://www.elektromodellflug.de/akku-test/bilder/kokam-3200.GIF
3s1p 80g each cell ---> 250g the pack...

so: 90g more weight..
BUT:
a lot more power !
pulling 70A in rc-car is no problem for this cell..

and also better voltage than your cells.. (= more speed)

[standard_63]

But, the 1900 mah lipo was being charged at 8 amps.... Probably the cause though. I haven't gotten the courage to actually go and buy those exact packs (TP 1900 mah packs) again and charge it at 8 amps... Maybe one day I'll do that. Sigh... never want to relive those memories again.


Isn't 8amps on a 1900 lipo way too high? I'm just asking because if so, then your fire can be easily avoided in the future?

[glassdoctor]

Correct... 1c is the max recomended charge for lipos= 1.9A for the 1900s.

[Wee Han Loh]

Hi Reinhard,

Thanks for the advise. My cell are Kokam SLPB 834374H which has 15C outputs.

However i have recently parallel these 3S packs and now no more expanding. Thanks guys for all the help.

Cheers.. ;)



QUOTE=Reinhard]@Wee Han Loh:
maybe you should also go up in capacity with your lipo-cell..

i think you had 2000mAh-cells..

15C rated..
so only 30A...
hmm..

i use this one:
http://www.kraeuterbutter.at/Bilder2/XXX-4/ThunderPower3s2p.jpeg
Thunderpower 3s2p 4200mAh
weight: 288g without wood-protectors

42A contiously (50A contin. with cooling)
63A 5sec-peaks
75A for less than a second..

this is way enough in a light rc-car:
(3,3Volt on 50A ==> 500Watt and peaks up to 700Watt)

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

your cells are this one i guess:
http://www.elektromodellflug.de/akku-test/bilder/kokam-2000.GIF
hmmm....
infact: realy light your setup:
3s1p 52g each cell ----> 160g the pack...


maybe you wana ad a little weight...
and take this cell if they fit:
http://www.elektromodellflug.de/akku-test/bilder/kokam-3200.GIF
3s1p 80g each cell ---> 250g the pack...

so: 90g more weight..
BUT:
a lot more power !
pulling 70A in rc-car is no problem for this cell..

and also better voltage than your cells.. (= more speed)[/QUOTE]