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Old Feb 01, 2014, 02:32 AM
2014% Newbie
United States, CA
Joined Jan 2014
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Alternative way to charge a lipo battery pack?

I need to have my plane flying in two days for personal reasons and my battery has ran out of power. My charge has also stopped working. I wa using the Turnigy 2s-3s balancer and was using the car battery as my source for power. Stopped charging for some reason. Is there an alternative way to charge a battery without having to buy these fancy chargers?
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Old Feb 01, 2014, 02:44 AM
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Letchworth, Great Britain (UK)
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I presume you're using a Turnigy balance-charger with your car battery, not simply a balancer? If so, it may have stopped charging because the car battery voltage has dropped too low -- have you run the car, or charged its battery, since you started charging the LiPos? If the input voltage drops below a certain threshold, the charger will simple stop working. Often it will give an error message, such as "Low input voltage", but not with simple ones like this http://www.hobbyking.com/hobbyking/s...02s%20balancer
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Old Feb 01, 2014, 03:31 AM
2014% Newbie
United States, CA
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Quote:
Originally Posted by abenn View Post
I presume you're using a Turnigy balance-charger with your car battery, not simply a balancer? If so, it may have stopped charging because the car battery voltage has dropped too low -- have you run the car, or charged its battery, since you started charging the LiPos? If the input voltage drops below a certain threshold, the charger will simple stop working. Often it will give an error message, such as "Low input voltage", but not with simple ones like this http://www.hobbyking.com/hobbyking/s...02s%20balancer
The link with the turnigy charger is the exact same one I'm currently using. Supposedly, once the green light is off then that means my battery is completely charged. Well I checked the battery by hooking it up to a small DC motor and it spins slowly... Almost as if my battery has no power at all.
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Old Feb 01, 2014, 06:26 AM
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Hook to a conventional DC power source with a resistor limiting the current. At the same time, connect a multimeter to check the voltage all the time. Disconnect when it reaches 4.2V/cell.
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Old Feb 01, 2014, 06:38 AM
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Another thought is if you ran the LiPo battery down too far, the charger will refuse to charge it. When a LiPo is discharged below its minimum safe voltage level, it become unstable and damaged. The charger will refuse to charge it then as there is a fire hazard where the damaged pack could ignite.
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Old Feb 01, 2014, 07:41 AM
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The simple answer is No, there is no other way to charge a Lipo. At least not safely.
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Old Feb 01, 2014, 09:06 AM
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Quote:
Originally Posted by Julez View Post
Hook to a conventional DC power source with a resistor limiting the current. At the same time, connect a multimeter to check the voltage all the time. Disconnect when it reaches 4.2V/cell.
This will work and has been used prior to good chargers being available but requires a variable voltage power supply.
For safety reasons, you would need to set the power supply to output 4.2V, no more, but I wouldn't go over 4V/cell and in fact, would look for someone with a charger to charge it for you if indeed your charger is broken..
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Old Feb 01, 2014, 10:39 AM
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Quote:
Originally Posted by woohoo704 View Post
Well I checked the battery by hooking it up to a small DC motor and it spins slowly... Almost as if my battery has no power at all.
Quote:
Originally Posted by earlwb View Post
Another thought is if you ran the LiPo battery down too far, the charger will refuse to charge it. When a LiPo is discharged below its minimum safe voltage level, it become unstable and damaged. The charger will refuse to charge it then as there is a fire hazard where the damaged pack could ignite.
^^^ +1 ^^^

I believe Earl has it right and you've simply destroyed your battery and your charger is likely fine. Easy to verify by checking voltage on the main output connector with a voltmeter. If it's less than 3.0 volts per cell, it's toast and should be completely discharged (if not already) and discarded.

Mark
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Old Feb 01, 2014, 11:29 PM
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Read this before you get another battery and charger: http://www.tjinguytech.com/charging-how-tos

Glen
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Old Feb 02, 2014, 08:07 PM
AMA 1051390
United States, NV, Henderson
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That wouldn't happen to be the Turnigy 420 "Charger" would it? That thing is a piece of junk and destroyed two of my batteries.
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