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Old Mar 22, 2005, 09:35 PM
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Help!
Tree incident makes lipo go below voltage? what to do

Hey, i have a 2s2p 2400 etec lipo battery pack and i think its below its limit voltage because my formosa was on for about 4 hours today while trying to get it out of a tree , and my apache 1215 charger is giving me a red blinking error i think because its below the voltage... i tested the pack and its a little above 6 volts... is there anything I can do to save it?

- thanks..
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Old Mar 22, 2005, 09:57 PM
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Quote:
Originally Posted by Scott5093
Hey, i have a 2s2p 2400 etec lipo battery pack and i think its below its limit voltage because my formosa was on for about 4 hours today while trying to get it out of a tree , and my apache 1215 charger is giving me a red blinking error i think because its below the voltage... i tested the pack and its a little above 6 volts... is there anything I can do to save it?

- thanks..
A slow charge at 0.1C 1/10 C until it reaches 7 volts resting and then place on Apachee and charge at approximately 0.3C mAh for the first charge. It most likely will recover most of its capacity.

How astrobob treats low voltage cells here.

Charles
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Old Mar 22, 2005, 10:07 PM
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hmm.. i tryed the lowest charge setting (80 mA) on my apache 1215 charger but its still giving me an error light.. i dont think its charging hmmm probably wont be able to recover it with my charger.... guess theres not much i can do
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Old Mar 22, 2005, 10:25 PM
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I had the same problem with a 3s pack in a tree for 2 days and my Apache 1500. I couldn't charge my pack but if you know someone with a Triton charger you might have them try for you.
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Old Mar 22, 2005, 10:26 PM
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Quote:
Originally Posted by Scott5093
hmm.. i tryed the lowest charge setting (80 mA) on my apache 1215 charger but its still giving me an error light.. i dont think its charging hmmm probably wont be able to recover it with my charger.... guess theres not much i can do
Most LI Poly chargers will not start a charge on a under voltage battery. An Astro Flight 109 will charge any Li Poly battery for the first 3 minutes regardless of its state of charge. Other means also work but I sometimes giving such advise on an open forum causes more problem than solutions.

Charles
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Old Mar 22, 2005, 11:38 PM
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i dont konw anybody with that chager so i guess the pack is done... good excuse to get a 3s setup since i just got a himax 2015 5400 ... thanks for the info though
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Old Mar 23, 2005, 04:05 AM
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No. Find a resistor of some sort - maybe 1k or so, and simply stick that in series with a charge lead and stick it on 12v - that limits curents to a few mA which will not damage even a puffed lipo - and afte a few hoiurs if its go any life left at all it will have enough volts to be chargeable by regular means.
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Old Mar 23, 2005, 07:51 AM
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vintage 1, So your saying to stick the resistor between the 12 volts and the battery? on + and - right?
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Old Mar 23, 2005, 09:11 AM
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If you can save the pack thats great but if not chalk it up to better safe than sorry.
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Old Mar 23, 2005, 09:17 AM
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The voltage must have been right below what my charger wanted because i left my pack outside last night and the voltage went up slightly above 6 volts. I then tryed it on my charger and it worked... im going to slow charge it after class today, but it would be good to know that thing with putting resistors on 12v in case it happens again
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Old Mar 23, 2005, 09:27 AM
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Thats odd. You would think that letting the pack get cold would lower not raise the voltage. Hope it works out just be careful and keep it in a fire safe container for a while.
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Old Mar 23, 2005, 09:40 AM
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I'm not sure, but I think Vintage is saying to install the resistor on 1 of the charge leads, not across or on both leads.
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Old Mar 23, 2005, 10:00 AM
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There is an antricle on using Wal-Wart Chargershere . On the RC Battery Clinic website.
Very (most) often a RC transmiter /receiver charger which came with your radio can be used with the proper resistor to charge other batteries. Charging Li Poly batteries with such devices should not be tried if you do not understand the basics involved.This is my opinion only but would hate for someone to burn down a shop ,house or suffer physical harm due to trying to revive a $40 battery.

Charles
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Old Mar 23, 2005, 11:27 AM
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good suggestion... saftey is always first... ill just have to learn more about how charging works if it does happen again
- thanks for the info everybody
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Old Mar 24, 2005, 06:07 AM
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I totally flattend a pack and it came up again. Another one did not.

What seems to happen is like with dry cells, the voltage 'recovers' a bit after a rest period. However not if they are up in a tree for 6 weeks..
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