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Old Jun 28, 2012, 08:02 PM
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Joined Jun 2012
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Help!
LiPo battery taking too long to charge

I have the stock battery for the E-sky Lama V4 and was charging it with the stock charger and it took about 5 hours to charge (the stock battery is rated for 800mAh, 10C discharge rate, 7.4V) I have not used the battery since and have it in a LiPo Safe.
Any help would be appreciated.
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Old Jun 28, 2012, 09:19 PM
RC Helicopter Pilot
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United States, CA, Westminster
Joined Mar 2010
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Is a stock charger one of those that just has a light?

Get a real charger so you can set the charge rate and you can see what is happening.

What is the voltage of the pack?
Are the 2 cells the same voltage?
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Old Jun 29, 2012, 02:43 PM
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From what Google can turn up it's a little ac/dc brick charger that you plug the balance connector into. Probably a pretty low charge rate, I could see it taking 2-3 hrs but I can't find the exact charge rate. However if it took that long it probably was having trouble balancing it. I would get a voltage meter that you can plug into the balance port and check the voltage of the individual cells. Something like this:
http://www.allerc.com/hyperion-eos-s...on-p-5701.html

Edit: Sounds like should be about an hour to charge. So either the battery is going bad or you over discharged it and it had a lot of trouble recharging it, in which case it's going bad as well.
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Old Jun 29, 2012, 05:43 PM
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Not balanced

I used a voltmeter to check if the cells were balanced and found that one of the cells was only 4 volts while the other one was 7.4 volts. The cell that had the 4 volt reading was slowly discharging on the small amount of current the voltmeter used to measure it. What should I do with the battery
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Old Jun 29, 2012, 07:09 PM
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Quote:
Originally Posted by Tyler103 View Post
I used a voltmeter to check if the cells were balanced and found that one of the cells was only 4 volts while the other one was 7.4 volts. The cell that had the 4 volt reading was slowly discharging on the small amount of current the voltmeter used to measure it. What should I do with the battery
You have measured the battery incorrectly. You measured the first cell OK but then you measured the pack voltage.

However if you got the correct voltage for one cell (4V) then the other cell is 3.4V. That difference is too great. I suspect your charger realized this and severely reduced the charge rate.

I would discharge the pack to zero volts. Use a power resistor or an automobile tail light for that. Then remove the mail connector and solder or twist the leads together. The pack is then OK to trash.

Glen
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Old Jun 30, 2012, 04:50 AM
A man with too many toys
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Quote:
Originally Posted by Tyler103 View Post
I used a voltmeter to check if the cells were balanced and found that one of the cells was only 4 volts while the other one was 7.4 volts. The cell that had the 4 volt reading was slowly discharging on the small amount of current the voltmeter used to measure it. What should I do with the battery
Those non-balance chargers are extremely dangerous and can cause fires. You should get a good balance charger before you burn the house down!


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Old Jun 30, 2012, 08:02 AM
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the charger has an output of 750mA or 800mA and charges through the balance wires. For it to take 5 hours to charge there is something wrong, as it has a 2hour cut off timer. Thats the part number ek2-0851.
1000mA for the newer type ek2-0852 Don't know if it has timer cut off.
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Old Jun 30, 2012, 08:12 AM
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Do yourself a favour and get a better charger .... I had similar with my RTF supplied chargers and gave up.... bought an Imax B6 of Ebay .... despite prophets of doom on forums - it works very well and even got those packs back working that the RTF charger had failed on ...

There's no need to trash a pack until all avenues are exhausted ............

Nigel
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Old Jun 30, 2012, 10:18 AM
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It IS a balance charger...

Quote:
Originally Posted by RC Man View Post
Those non-balance chargers are extremely dangerous and can cause fires. You should get a good balance charger before you burn the house down!


The battery charger I have is a balance charger. I think the problem is the one of the battery leads is shorted to the other one. Thanks for the help anyway
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Old Jun 30, 2012, 10:33 AM
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Originally Posted by traxx de maxx View Post
the charger has an output of 750mA or 800mA and charges through the balance wires. For it to take 5 hours to charge there is something wrong, as it has a 2hour cut off timer. Thats the part number ek2-0851.
1000mA for the newer type ek2-0852 Don't know if it has timer cut off.
I think that the battery is trash and the charger was not able to charge it correctly because the battery has one of the balance plug leads shorted together and only works properly through the JST port and when the charger tried to discharge one cell it also discharged the other one making the charging take much longer than usual and potentially damaging the battery. I have a upgrade battery that is working much better than the stock battery so I will probably just discharge the battery to 0 volts and throw it away because I can get new one for only $4
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Last edited by Tyler103; Jun 30, 2012 at 10:36 AM. Reason: Accidentally hit the enter button
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Old Jun 30, 2012, 10:44 AM
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Good decision with the battery, now make the same one about the charger.
Save the rest of your LiPo, get a real charger.
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