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HelicopterMain Discussion › Please discuss, my lipo wont charge
12-02-2005 02:14 PM  12 years agoPost 1
Gadgets

rrApprentice

South Africa

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I put it on to charge at even 0.1C but it only takes about 50mah and thats it.
The lipo is dead.
Any ideas, there is no swelling or anything.
I am using a kokam charger and these are TP cells. Must have had about 10 flights.

All my other lipos charge.





I see plank flyers!!!

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12-02-2005 02:22 PM  12 years agoPost 2
BarracudaHockey

rrMaster

Jacksonville FL

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Any chance you left it on and pulled it below the miniumum volts per cell?

Andy
AMA 77227
http://www.jaxrc.com

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12-02-2005 02:22 PM  12 years agoPost 3
GM1

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Tallahassee, Florida US

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Not an expert

I am NOT a battery expert and am doing this from memory. Lipos are VERY picky about voltage. If the voltage drops below about 2.3V per cell (I think), the battery can be damaged. Sometimes you can "force" the charger to charge a low battery BUT be VERY cautious about it and do it only for a short period (2 minutes max) of time as it can cause a fire, so NEVER leave it unattended. By doing this, and if the battery is not seriously damaged, you can get the battery voltage up enough so the charger will recognize the battery and charge it normally.
Gordie

On a dog sled team, if you're not the lead dog, the view never changes.

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12-02-2005 07:57 PM  12 years agoPost 4
NZ_Neil

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Auckland, New Zealand

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A lipo does not need swell to be dead.

But if the Lipo has been allowed to sink below 3v (per cell) for any length of time it will dye.

The syptoms you describe of the Charger pumping in 50mah then stopping is exactly what chargers do when the Lipo is dead.

Try leaving a 3s Lipo plugged into a in foamy for a couple of hours and get the voltage down to about 6v (lipo min should be 9v) this will cause the Lipo to be Toast it will never charge again and there is no swelling.

Regards
Neil Harker
New Zealand

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12-02-2005 08:08 PM  12 years agoPost 5
Thomashome

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West Sussex UK

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One of mine went belly up, I phoned up the manufacturer, the chap there told me to set the charger (schulze) to Nicad to get the voltage up, I did till it got to 10v while keeping a close eye on it and it's been fine ever since.

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12-02-2005 08:31 PM  12 years agoPost 6
erichelipilot

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Worthing, SD USA

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NZ_Neil - I hate to say this, but you are not correct. I had one that went below 3v per cell and I put it on the Nicad setting for a little while, and then charged it on the lipo setting and everything is fine. Be very careful when doing this.

_________________________________________________________ Love my Evo!!

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12-02-2005 08:54 PM  12 years agoPost 7
FLYINFOOL

rrKey Veteran

Cudahy, WI

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If you have access to a power supply that will limit both current and voltage.
Set the current for a C0.1 and the voltage to 1V less than the nominal pack voltage. Let it cook on this for an hour then go back to your normal charger.

If you are going to use the NiCd charger route make sure to set the current way down from you would hit a NiCd with.

Either way do this outside in the driveway.

We tried to blow up a pack once.
A club member had a very swelled 3s pack,
so we set it up on a stump, set up the video camera on a tripod., got out some jumper cables and connected the pack direct to a car battery.
After watching nothing for 45 min. it dawned on us that we were feeding12.0V to a battery that normaly charges to 12.6V. DOH


Jeff Borowski
RAMS Club President
www.ramsrcclub.com

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12-02-2005 11:24 PM  12 years agoPost 8
NZ_Neil

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Auckland, New Zealand

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erichelipilot Wrote : NZ_Neil - I hate to say this, but you are not correct. I had one that went below 3v per cell and I put it on the Nicad setting for a little while, and then charged it on the lipo setting and everything is fine. Be very careful when doing this.
I too have tried to recover lipos that have fallen well below the 3v limit by pumping in a constatnt charge with no joy. Maybe you were just lucky and I am sure its to do with the length of the time the cell sits around in an extreme discharged state. I have now killed two 3s Tanic Lipos (I have about 20)

If I am wrong why are there so many Lipo threads and articles telling you that your Lipos will be Toast when discharged below 3v per cell ?

Neil Harker

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12-03-2005 01:05 AM  12 years agoPost 9
erichelipilot

rrApprentice

Worthing, SD USA

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I guess I worded that one incorectly. I have had a couple of people around here do the nicad method with 100% success. This was with Kokam and Thunder Power cells.

_________________________________________________________ Love my Evo!!

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12-03-2005 09:04 AM  12 years agoPost 10
w.pasman

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Netherlands

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Can you measure the open end voltage (that is, without anything connected to the battery)?
That will tell if it was overdischarged or if there is a shortcircuit.

Don't try the recommendation of FLYINFOOL: you really have to know what you are doing and electronics and LiPo charging technology probably is not your area otherwise you would not have posted here. You risk exploding pack if you try what he says but make a mistake.

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12-05-2005 07:01 AM  12 years agoPost 11
Gadgets

rrApprentice

South Africa

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Thanks for the reply so far guys.

I did check the open end voltage and it reads 12.35V.

Now I am really confused. Do these thing get a memory, like nicads?

I will try the constant voltage thing for 2 minutes and see.

once again thanks.

If all else fails maybe I use it to fire up the Bar-b-que





I see plank flyers!!!

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12-05-2005 11:07 AM  12 years agoPost 12
Spacey

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Pretoria, South Africa

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All good info here.

Gadgets: We have also done what is described above but I have to stress that this only happens when the battery is discharged too far. And the scenario also usually only creeps up with the smaller/cheaper chargers like the swallow. If you have a friend with a Robbe Infinity (I know alot of folks in ZA has this one) which can also do lipos you could try charging it with that though on the normal lipo settings as you would with your kokam charger. The Robbe for some reason usually does the trick with zero hazard. I don't know why but the swallow is just sometimes too fussy. Just a couple of thoughts for you.

Cheers
Rudolf

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12-05-2005 02:50 PM  12 years agoPost 13
FLYINFOOL

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Cudahy, WI

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w.pasman
Your right, I should have thrown in the disclaimer to try this only if you are comfortable working with electronics and power supplies.
The method that I put forth does have some significant risks if you don’t know what you are doing.


Jeff Borowski
RAMS Club President
www.ramsrcclub.com

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12-05-2005 05:15 PM  12 years agoPost 14
w.pasman

rrElite Veteran

Netherlands

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12V. Sounds like a full 3S pack.
Is it right that you have a 3S pack?
If so, do you have your charger correctly set up for 3S?
Are you sure it is not already full?

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12-05-2005 10:21 PM  12 years agoPost 15
FLYINFOOL

rrKey Veteran

Cudahy, WI

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Does your charger have a discharge feature that is LiPo safe (9v cutoff)?
If so try discharging the pack to see how much power is really in there and then recharge.
12.35V is very nearly a full charge for 3s.
If you have 12.35 open circuit volts and the pack will not show near normal capacity for discharge and will not accept a charge then odds are that you have one or more bad cells, or a bad charger.
Since you say your other packs charge normally it's probably not the charger.


Jeff Borowski
RAMS Club President
www.ramsrcclub.com

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12-07-2005 06:54 AM  12 years agoPost 16
Gadgets

rrApprentice

South Africa

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Ok!

I took it to a friend with an Infinity 2 chargr, and that did not help.

So I tried to use a normal 12V charger AND

I fat packed the F$#^&*$%^ thing.





I see plank flyers!!!

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12-07-2005 07:51 PM  12 years agoPost 17
w.pasman

rrElite Veteran

Netherlands

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So I tried to use a normal 12V charger AND
I fat packed the F$#^&*$%^ thing.
You did what !? Normal charger?!!? That is dangerous !!!
And what happened? "fat packed" what is that?

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12-08-2005 01:21 AM  12 years agoPost 18
FLYINFOOL

rrKey Veteran

Cudahy, WI

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Fat pack is what you have just before all of the installed smoke, FIRE and Jell-O falls out of the pack.
Do not even bring that fat pack in the house, it is an incendiary device just waiting to go off.

Please give us more details as to exactly what you did, we can tell you where you went wrong, so that you do not repeat this.


Jeff Borowski
RAMS Club President
www.ramsrcclub.com

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12-08-2005 02:10 AM  12 years agoPost 19
mdgyro

rrApprentice

Hawkinsville,GA

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I have a battery that will show 12.5 volts until you put a load on it (with a triton charger in discharge mode) and then it drops to 9.3 almost instantly it will hold at 9.3 for a minute or two then drop to 9 and the cycler stops. It has never been below 9v

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12-08-2005 08:49 AM  12 years agoPost 20
Gadgets

rrApprentice

South Africa

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The infinity2 did nothing.

After about 5min at 0.1C on the infinity2, the lipo still showed 12.35V

I put a load on it and it droped to 9.xx volts.

Put it back on the the infinity and nothing changed.

Someone suggested a power supply at over 12.35 and at 0.1C.

I tried this for 5min (did not get warm) and left the pack unplugged overnight.

In the morning the pack was swollen.

Rather it happened on the ground. But yes please any advise will be appreciated.





I see plank flyers!!!

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HelicopterMain Discussion › Please discuss, my lipo wont charge
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