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Old 08-07-2011, 08:36 AM   #1
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Default I need Lipo 2S Discharge Advice

I have several Lipo 5000 (2S) battery packs (anywhere from 20C to 50C) that I want to discharge for storage. I have a Thunder AC6 dual power charger that has a discharge function and a storage function. Problem is, the max I can discharge a 2S at is 1.0A and it takes FOREVER. Other than taking the batteries out and running them in the car - not recommended on rainy days - I am wondering if I can use an old trick we used to use with NM and NiCad batteries. Can I attach a bar of 1157 bulbs FOR A SHORT PERIOD OF TIME, keeping an eye on the discharge rate with a balance meter, or would this take the power out too fast. I also have a 3600 and a 4800 Orion. Any good tips would be appreciated. Thanks.
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Old 08-07-2011, 08:45 AM   #2
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I use my charger's storage function for all my lipos ranging from 2S 200mah to 5S 5200mah regardless of the time it takes. Normally all the packs have been used in racing heats so the amount left is less than full but above half. It takes about 45 to 90 minutes to bring each to storage levels,

This is much safer than taking a chance of overdischarging them using bulbs. All you need is that one distracting phone call or a "honey do" chore to forget about monitoring the pack and you now have a worthless lump.
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Old 08-07-2011, 10:08 AM   #3
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Bulbs will work just fine, just make sure you watch the voltage like you said. I wouldn't worry about amp draw unless you're going to put 30 bulbs on it.. 8-10 bulbs isn't going to be an issue as far as amps go...
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Old 08-07-2011, 12:29 PM   #4
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The bulbs will work fine as long as you monitor the voltage and avoid over discharging. Its not practical as you've noticed to use your AC6 (or most chargers for that matter) for discharging them. As long as you reduce the voltage down from max of 4.2v/cell, there's no harm in letting them sit til the weather clears and then discharging them in your RC.
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Old 08-07-2011, 12:47 PM   #5
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As long as you are only talking 2s packs, you can pick up older NiXX high end car chargers for dirt cheap. Almost all of them have good discharge capability for a 2s pack. Those will allow you to set the discharge cut-off so you don't have to watch them like you would bulbs.
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Old 08-07-2011, 12:53 PM   #6
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Personally, I don't discharge lipos - I run them down, but I don't live where it rains - well, at least hardly ever....we're 18" under for the year and in the worst drought since 1915 here. It's rained twice at our house since end of Feb.


This was in reply to LadiesFirst orig post.....
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Old 08-07-2011, 05:13 PM   #7
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Thank you all for your advice. You verified some things for me that I was considering. AreCee, you are totally correct in that if you get one distraction, then it could be disastrous. In fact, that did happen when I was trying to just bump a Lipo UP to 3.85 and I ended up charging it fully. So then I did use the Lipo storage program to bring it down. So I probably won't do the light bar, as much as I'd like to.

I did use the charger after all, even though it did take awhile. It did do a good job. I have one battery I don't feel too confident in, so that is the one I was referring to above that I charged and then brought back down, rather than storage charge it. Since I had never used the charger for storage, I wasn't too sure if it would charge it up to 3.85. But I am pretty sure it does. The charger I have does storage, discharge, charging, and other features, and did work well - it's just slower than I'd like. Usually after racing the batteries are basically near storage rate; however, I had charged them up at the track after the races to practice, and we ran out of practice time, so I wanted to bring them down to a safe 3.85 because I am not sure when the next time we will use them will be. Thanks again everybody!
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