What the?? 7.4volt 250mAh 2s lipo's went bang on first plug in

[millzee]

Hi, I thought I'd share the experience I had today. After waiting nearly a month for them to arrive (the losb9825 s) I took them out of the packet, removed the losi connector and attached a jst2 connector as I have with lots of batteries b4 and then went to charge them on my Hitech x4 charger. I connected each lipo into an octopus connector that then goes into the charger, same as I connect all my other lipo's (I always check polarity) and even with the charger not delivering any power to them I noticed a strange sound comming from the first lipo I connected, I went to feel it and it went poof so I quickly unpluged both leads from the charger and threw them to the ground. I checked the 2nd lipo now that it was on the ground and I could see and feel the heat in both the wires and the lipo, the first lipo had a big blow out, I think I unplugged the 2nd one just in time, it's very swallen. At first I thought that maybe I am supposed to have charged them through the balance plug but after doing some research on the net and speaking with the Australian distributor it seems this is not the case, he say's you can charge them with either lead.
I took some pic's of my charging set up and in one of them I am charging a 180mAh losi lipo with the exact connections that I used with the 250mAh blow out and Im also charging a NiMH with the same connections used.

[Steven Vaccaro]

Are you sure the charge rate wasn't to high?

[domwilson]

That was my first thought..

[millzee]

it did this with no current going to the batteries at all, I'd just plugged them into the same connections that I'd been charging other lipo's with all morning and be I pressed the start button this happened. I'm stumped, I checked the polarity be plugging and this occured, the Xcelorbombs just made a whistle, got real hot real quick and as I was pulling out the leads to the charger, one lipo blew out the sides.

[eric_laermans]

There is only one remedy for this pack left. Take a bucket and fill it with water. Put some salt in the water and put the LiPo in it too. Make sure the LiPo is fully under water and take it all outside. Take a sharp knife and make a slice through the LiPo-pack. Run... wait and enjoy the LiPo blowing some steam off. After a while the LiPo is not dangerous anymore.

[LiPo Power]

Did you have more than 1 battery connected to your octopus wires when this was going on?

[785boats]

Those bare 4mm banana plugs in each octopus worry me. If they were touching, there would be a dead short across your battery on plug in. Could that have been the cause?
In your top picture the negative banana of one octopus is actually sitting on the bare shell of the connector underneath it. In the other harness the positive & negative bananas are only 1/4" apart. And that's while you are charging. You should slip a piece of tubing over those connectors when they are not in use.
I also notice that the balance plug is not plugged into the balance board. Is there a reason that you don't plug the balance plug in & balance the pack while you are charging?
Cheers.
Paul

[millzee]

Those bare 4mm banana plugs in each octopus worry me. If they were touching, there would be a dead short across your battery on plug in. Could that have been the cause?
In your top picture the negative banana of one octopus is actually sitting on the bare shell of the connector underneath it. In the other harness the positive & negative bananas are only 1/4" apart. And that's while you are charging. You should slip a piece of tubing over those connectors when they are not in use.
I also notice that the balance plug is not plugged into the balance board. Is there a reason that you don't plug the balance plug in & balance the pack while you are charging?
Cheers.
Paul

Did you have more than 1 battery connected to your octopus wires when this was going on?

Yeah, I was only charging I battery at a time and it puzzle me further about the octopus leads touching, I understand how that could cause a problem but as I've said, I've charged other brand lipo's over 100 times with no issues, even after blowing the 2 xcelorin batteries, I plugged up more, other brand lipos and charged them without an issue.

[drwayne]

Gday Danny.
FWIW I charge littluns like this with the balance leads inline.. makes for better stability.
That aside.. Id check the JST polarity with a multimeter.. I note the balance plug is [Bl.Bl.Red].. and I bet that is [7.4,3.7,gnd] ...
When I first had packs manuf in Cn.. the plugs were correct.. the wire colors were random !

regs
DocW
Adelaide
Australia

[millzee]

here's some pic's of the internals of both batteries, I dunno, these are the first lipo's I've opened up, do they look alright to you??

[drwayne]

ok.. balance plug [Bl.Bl.Red] is [gnd,3.7,7.4]

Id still check polarity over the wires

rare but not impossible for dead/dud cells.

W

[Rich]

I had bought one of these from my local hobby shop and one of the cells was bad. I tried to charge it to revive the cell but it got warm and the charger told me it was charged. I hooked it up to a blinky and saw one cell was bad.

[millzee]

That's a shame for you but it helps my mind rest at the fact that these are just crrapp batteries.

[Rich]

I figured it would, I took it back to my hobby shop and the guy just cut me leads off and gave them back to me along with a new lipo at no charge!

[Brushless55]

Glad to hear you got a new lipo..!
I have two of the Dynamite versions on there way for my micro cars....