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Old 06-10-2008
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Default Trakpower voltage

I have recently bought 2 second hand lipo cells from somebody that said they had been used very little. 1 of them seems fine but 1 of them doesnt seem to be charging. When i plug the leads in there is nothing at all. I checked the voltage on the Dodgy one and it was around 5.8v. Is this normal?

Cheers

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Old 06-10-2008
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they aren't meant to be discharged below 6v, so i would say that pack isn;t much good
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Old 06-10-2008
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The minimum acceptable voltage of a Lipo is 6 volts.

It is VERY VERY dangerous to attempt to charge a pack of lipos that has dropped below 6 volts. If you do attempt to charge a Lipo that has dropped below 6 volts it will be highly likely to EXPLODE !!!

Get in touch with Trakpower and ask them how to deal with the situation.

Put the battery somewhere safe until you can speak to Trakpower. If you have a safe charge pouch you should put it in that and away from anything flamable just to be on the safe side.
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Old 06-10-2008
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Maybe put it in a bucket fo sand?

A
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Old 06-10-2008
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Quote:
Originally Posted by Body Paint View Post
The minimum acceptable voltage of a Lipo is 6 volts.

It is VERY VERY dangerous to attempt to charge a pack of lipos that has dropped below 6 volts. If you do attempt to charge a Lipo that has dropped below 6 volts it will be highly likely to EXPLODE !!!

Get in touch with Trakpower and ask them how to deal with the situation.

Put the battery somewhere safe until you can speak to Trakpower. If you have a safe charge pouch you should put it in that and away from anything flamable just to be on the safe side.

thats a bit extreme it wont explode......................
if its not swollen, pm me and ill explain how to recover it, if its swollen then dispose of it, slowly discharge it at a low amperage till its completly flat then bin it.

lipo will not expolde or catch fire if they are discharged below 6 volts at a low amperage, it will 99% just leave the pack useless, you can sometimes safley recover them
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Old 07-10-2008
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Please ring a profesional, ie. Trakpower

Whilst it is unlikely the Lipo will explode it is possible. Like I said, "be on the safe side"
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Old 07-10-2008
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Quote:
Originally Posted by Body Paint View Post
Please ring a profesional, ie. Trakpower

Whilst it is unlikely the Lipo will explode it is possible. Like I said, "be on the safe side"
i am in contact with trakpower and dont offer that sort of info without checking with them 1st!!
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Old 07-10-2008
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Just for the info,

I've got a really old pack thats given up and swelled. Phoned trakpower to find out what to do with it, and they told me to either dump it slowly and then bin it or if i wanted to go to greater lengths, fill a bucket with water, put in salt till it wont dissolve anymore then stick the pack in over night. Guy said it will totally kill the pack off safely, then can stick it in the bin.

cheers

craig
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Old 07-10-2008
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Quote:
Originally Posted by craigosh View Post
Just for the info,

I've got a really old pack thats given up and swelled. Phoned trakpower to find out what to do with it, and they told me to either dump it slowly and then bin it or if i wanted to go to greater lengths, fill a bucket with water, put in salt till it wont dissolve anymore then stick the pack in over night. Guy said it will totally kill the pack off safely, then can stick it in the bin.

cheers

craig

100% correct, to dump it a bulb is suitable, such as a car stop lamp bulb or a discharger set at .5 amps or lower.
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Old 08-03-2009
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Hi,

I have an orion 3600 lipo which I bought second hand, but boxed as new, a while back. The lipo has died but hasn't swollen and looks normal so I've stopped using it, the reason for it's death being a combination of things from what I can tell...I thought I'd post some details as a warning to others having learnt the hard way!

1) Over discharging - Not using a cutoff! Which I knew was bad, but I only run at a club and top up, worst case every 2 heats, but normally every after every heat, which I figured was minimising the risk. I run a novak GTB (old one without lipo cutoff) & 10.5t brushless in a b4, so I figured not the most power hungry of setups.

2) Shorting it out a few times - Disconnecting the wrong end of the charging cables when rushing and momentarily shorting the pack, again I know this is bad, but when your rushing around at a meeting the stupidest things can happen unless your really careful!!! When using NiMH cells and open contacts you HAVE to be really carefull with ALL the handling, fully sealed lipo's look much safer, but there are still some risks to remember!

3) Possibly overcharging it - My charger is a Intellipeak ICE, and a has a charge capacity setting on it. I had this set to 110% (left over from the old NiMH setting I used to use before I changed it to CC-CV charging the lipo). Also, I wasn't balance charging either.

So, I'm not sure which of these has been doing the most damage, but all in all I could have treated the pack better and thankfully the pack has died gracefully rather than going bang.

The pack has been sat idle for a few months now, and this morning out of curiousity I measured the voltages accross the pack to see what it was at before disposing of it.

Measured across the main + & - the pack measures 4.06v, well below the minimum 6v for a lipo. I then measured + to balancing port at 0.009v, and balancing port to - at 4.06v. The other good packs I have measure evenly accross the balancing port as you'd expect. Clearly I have a very dead cell in the pack!

So now I'd like to dispose of the pack, knowing I've learnt a few lessons about lipo's.

The main question I have is...I'd like to discharge the pack properly and safely before I bin it, but being as I have a very dead cell in the pack, would discharging the pack very slowly on my ICE be a safe thing to do?

Sorry for the lenthy post, but I thought some details would help.

Cheers
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Old 08-03-2009
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its possible to discharge the good cell through the bance port and main connector, just set discharge min to zero volts
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Old 08-03-2009
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Cheers, I'll give that go.
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  #13  
Old 08-03-2009
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We had one last night that had been used until it stopped at 5.2volts!!
Was a brand new TP 4900.
BC8 charger was equipped to recover it to full health again though
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Old 08-03-2009
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Wow...that is low!

Out of interest, what did the BC8 do to recover it?

Will be interesting to see how that battery holds long term.
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Old 08-03-2009
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Quote:
Originally Posted by blue_pinky View Post
Cheers, I'll give that go.
I suspect yours cells aren't actually dead. The Orion packs have a fuseable link inside designed to blow in the event of the pack's output being shorted. You are probably measuring one good cell and getting no reading off the other cell because it is disconnected due to the link blowing.

I don't know if Orion can/will repair the pack, but probably worth checking before you write it off.
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Old 08-03-2009
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Oh really....it'd be cool if that's the case, I'll try and get in touch with them and see what they say.

One question though, if that link had blown would you still expect to be able to read a voltage across the main + & - terminals?
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Old 08-03-2009
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Actually, no, I didn't read your post properly. I would have expected you to get no reading across the main terminals if it was blown.

Seems odd that one cell is fairly well charged but the other is completely dead. I don't know if damage can cause a cell's voltage to fall away to zero.
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Old 08-03-2009
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Quote:
Originally Posted by blue_pinky View Post
Wow...that is low!

Out of interest, what did the BC8 do to recover it?

Will be interesting to see how that battery holds long term.
there is a way to recover lipo, but its NOT recemended due to saftey grounds

ill explain, but take notice of the warnings

DO NOT leave tha pack unattended while doing this.

if the pack is too low where a lipo charger will not charge it, you can put it on a nimh charger on nimh mode, charge the pack ALL THE TIME YOU MUST MONITER THE VOLTAGE, when the pack voltage is over 6 volts, disconect and then charge the pack on your charger in lipo mode.

all you are doing is bypassing the lipo chargers auto cell/voltage check.

you MUST not fully charge, ONLY use this to recover the pack to just over 6 volts.

i have done this to several packs and all are still fine.

PLEASE take extreme care when doing this, not that the pack will go bang if you try, just do not over charge the pack
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Old 08-03-2009
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Hey Blue Pinky, I think you should have been a little more careful as you seem to have broken all the rules - I for one would not like to be anywhere near your charging and discharging techniques. All batteries are dangerous, and you should do a bit more homework BEFORE you charge and discharge them, not practice around innocent racers! A bit late now, but something to think about......
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Old 09-03-2009
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Thanks Dazzler...but hopefully I'm not a complete hazard to the rc world...so I feel like I have to explain a few things that I left out initially because my first post was long enough already!

I have a smart stop cutoff from my bashing car that I now use used in my club car every week...but knowing that a single race only used about 800mah-1000mah (having measured it many times), I'd previously decided it was a low risk and sometimes I didn't swap it into my club car. So calculated risk, and the 2 or 3 times it did seem to run down I stopped immediately, just as the warning label on the battery tells you to.

Also, I re-read my charger manual and the "charge capacity" setting I mentioned does not over charge the cells...it's a safety feature for preventing it! So I can strike that one off the list

All in all I know I should have been more careful but the battery hasn't blown up and no harm has come to anyone or anything, I just have a battery that's died prematurely.
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