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Old 03-07-2011, 07:39 AM   #1
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Default lipo discharge question

I have a Gens ace 4000 mah 25c lipo pack. The first time I ran it in my car the gears stripped. (too hot of a brushless setup) It'll probably be a little time before I get it fixed and run my lipos again. I know I should discharge my packs. I'm just not sure at what rate?
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Old 03-07-2011, 07:42 AM   #2
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I have a Gens ace 4000 mah 25c lipo pack. The first time I ran it in my car the gears stripped. (too hot of a brushless setup) It'll probably be a little time before I get it fixed and run my lipos again. I know I should discharge my packs. I'm just not sure at what rate?
it depends on your charger, the charger needs to be able to dissipate the heat generated from the discharge. i discharge my packs at 1 amp, so that way i know that in 1 hour, ill pull 1000mah out. discharge the park until the voltage is between 3.6 and 3.8 volts per cell and the packs will be good until you get replacement parts. it will also help if you run a fan on the charger and power supply while you are discharging.
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Old 03-07-2011, 10:06 AM   #3
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I have a Thunder AC 6 charger from hobbypartz.com.
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Old 03-07-2011, 11:53 AM   #4
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the charger will actually start at a lower rate and slowly work its way up to what you programmed into it. if it can not tolerate a discharge rate as high as you programmed, then it will stop at whatever rate it can handle. like i said, i normally use 1C so that i know ill be taking out 1000maH per hour and i can set a timer to make sure that i dont over discharge. most chargers can not tell what type of battery it is you are discharging so it could over discharge so set a timer either way.
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Old 03-07-2011, 05:47 PM   #5
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The thunder ac6 actually has a storage mode that works great...Just cycle thru the lipo modes and you will find it.Simply set it for 2s or 3s and the discharge rate...the manuel suggests .06 for a 2s, this is what i use.

Go to http://www.rchelicopterfun.com/rc-lipo-batteries.html this link to learn about lipo batteries...credit for finding this link goes to Duster_360.

Good Luck
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Old 03-07-2011, 06:12 PM   #6
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the lower discharge rate should be better (0.6)
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Old 03-07-2011, 07:29 PM   #7
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The AC6 has a discharge limit of only 5watts and a max of 1amp, so the discharge rate is going to be limited by the charger based on whatever the lipo voltage is.

So if you start at 8.4v, all you'll get for disch current is 5watts/8.4v =~0.6a.
At storage voltage disch rate will be 0.65v.

Use the storage mode like racer53 advised, it'll protect the lipo from overdischarging - just be prepared for it to take some time.

You'll be better off if you can run the lipo down in a RC rather than on the charger due to the low discharge watt limit. If you can't do that, a 1157 automobile tail light bulb soldered up with the right connector for your lipo will give you a ~1amp discharge. You'll need to monitor voltage doing it that way though. Bulb also gets hot - I used to put bulb in an ashtray when I had to disch that way.
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Old 03-07-2011, 10:12 PM   #8
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Quote:
Originally Posted by Duster_360 View Post
The AC6 has a discharge limit of only 5watts and a max of 1amp, so the discharge rate is going to be limited by the charger based on whatever the lipo voltage is.

So if you start at 8.4v, all you'll get for disch current is 5watts/8.4v =~0.6a.
At storage voltage disch rate will be 0.65v.

Use the storage mode like racer53 advised, it'll protect the lipo from overdischarging - just be prepared for it to take some time.

You'll be better off if you can run the lipo down in a RC rather than on the charger due to the low discharge watt limit. If you can't do that, a 1157 automobile tail light bulb soldered up with the right connector for your lipo will give you a ~1amp discharge. You'll need to monitor voltage doing it that way though. Bulb also gets hot - I used to put bulb in an ashtray when I had to disch that way.
If your using that charger to discharge you'll probably have to increase the time limit on the charger as they are usually 120 mins default from memory, not long enough to discharge a full pack to storage at the rate it can handle.

The light globe is a good way to discharge but i recommend fitting a cell monitor (Low Voltage alarm).

http://www.hobbyking.com/hobbyking/s...idProduct=7224

they are cheap and will remind you if you forget about it.
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Old 03-08-2011, 10:53 AM   #9
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If your using that charger to discharge you'll probably have to increase the time limit on the charger as they are usually 120 mins default from memory, not long enough to discharge a full pack to storage at the rate it can handle.

The light globe is a good way to discharge but i recommend fitting a cell monitor (Low Voltage alarm).

http://www.hobbyking.com/hobbyking/s...idProduct=7224

they are cheap and will remind you if you forget about it.
if you use a method like a light bulb def! get a cell monitor. one deep discharge and the pack could be toast.
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