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LiIon, LiPo, NiCd & NiMh General General Battery Support


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Old 05-11-2012, 09:51 PM   #1
Rollin_3z
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Default Make your own dishcharger for big lipo packs

Hi guys, dont know if this has been posted before, but if you have lots of 6s batts for large helis and dont end up using them at the field you can build your own discharger.
I was using my icharger at 3amp discharge at 50 watts and it was taking forever to get to 3.90 volts per cell. Plus the unit got so hot even with the fan on, that it finally destoyed the load resistors inside (?) and now only discharges at 1.2 amps

My friend had the idea of using car head lights which are 12 volts 65 watts in series to discharge 24 volt 6s packs. It discharges my 3300mah 6s packs from 4.2 volts to 3.85 volts in 10-12 minutes and about 18 minutes for 5000 mah packs.

You can add this lipo balance checker with Alarm set to your storage voltage, so you dont have to keep an eye on it while it discharges

http://www.hobbyking.com/hobbyking/s...2_8S_Lipo.html





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Old 05-12-2012, 12:09 AM   #2
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I have used car headlamps too. But now I found something even better. I charge up the packs just when I want to fly.. with the proper setup you can charge one or two 6s5000mah packs in just 12-15 minutes. I never have to discharge anymore since I charge the next flight as I fly the current flight.
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Old 05-12-2012, 09:49 AM   #3
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I have used car headlamps too. But now I found something even better. I charge up the packs just when I want to fly.. with the proper setup you can charge one or two 6s5000mah packs in just 12-15 minutes. I never have to discharge anymore since I charge the next flight as I fly the current flight.
Oh ok umm, I like to charge all my packs at home and not off my car at the field. My car batt died once and is not as strong as before. I dont want to buy a generator. This is a good option for me when Ieave I for home with charged packs...
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Old 05-12-2012, 11:30 AM   #4
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Very true. I use deep cycles for power (but have plenty of room in the back of the truck) Good writeup. My first 3 years I have tons of packs and many chargers.. so that would have been great to have. I didn't discover headlights until my 3rd year.
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Old 05-12-2012, 12:15 PM   #5
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Back in the 80s, I won this Dean's light bar in a car race. Its got 10 automotive bulbs and an auto cutt-off for NiCads. Turn it over and doubles as a car stand.

I've adapted it to LiPos by removing the auto-cutoff and wired so that it can be 12v (3s) or 24v (6s). Its about 250-300 watts. Though it works well, it can get pretty hot if you run for an extended period of time. I usually have a fan on it to keep the temps in check.

I've been thing about putting something together that is a little more compact and has a built-in fan. Kind of like this one. http://www.tjinguytech.com/my-projec...ipo-discharger But with tow Powerlab8s I have 200 watts of internal discharge plus quite a bit more of I use the Pb battery with the light bar in parallel.

Here's a couple pictures of it. Not mine, just some images I found on RCG.




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Old 05-12-2012, 09:58 PM   #6
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Lots of good ideas here. I just dont like the heat build up using our chargers to discharge. As I stated, I destroyed something inside my icharger discharging a large 6s lipo pack.Safer to use light bulbs and burn out one of those and replace.
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Old 05-12-2012, 10:01 PM   #7
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If you use the regenerative discharge ability that's built into certain chargers, they won't generate any heat. I'm not sure if your charger has that feature, but some of the new ones do. No energy is used up in the form up heat. That's what I do with my 6S 1300mah packs and it only takes about 10 min to discharge each one @ 10 amps. That's about the only time I use my car battery...
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Old 05-13-2012, 12:36 PM   #8
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If you use the regenerative discharge ability that's built into certain chargers, they won't generate any heat. I'm not sure if your charger has that feature, but some of the new ones do. No energy is used up in the form up heat. That's what I do with my 6S 1300mah packs and it only takes about 10 min to discharge each one @ 10 amps. That's about the only time I use my car battery...
I never thought of that either. Discharge at the field with your car battery using the ichargers regen discharge. Going to try that today at the field
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Old 05-13-2012, 01:15 PM   #9
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It doesn't work on a car battery since they are usually full. (Unless you drained it a lot by charging packs)... best is a deep cycle and at the end of the day you might be down to 30 or 40%... now you can pump the juice back in.
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Old 05-13-2012, 06:50 PM   #10
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I built this with a couple of relays, and a cellog 8S.

I works like a champ and brings them down to a perfect storage charge avery time.



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Old 05-13-2012, 11:50 PM   #11
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Quote:
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It doesn't work on a car battery since they are usually full. (Unless you drained it a lot by charging packs)... best is a deep cycle and at the end of the day you might be down to 30 or 40%... now you can pump the juice back in.
True. My solution is to simply turn on my heated seats while discharging. As soon as I do that, the car battery voltage drops enough so the charger can throw more amps at it. It's an optima yellow top deep cycle...
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Old 05-16-2012, 11:11 AM   #12
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Quote:
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True. My solution is to simply turn on my heated seats while discharging. As soon as I do that, the car battery voltage drops enough so the charger can throw more amps at it. It's an optima yellow top deep cycle...
Ok, now we're just being silly...Hold your left nutsack whilst you plug the positive lead of the charger into your "right" nostril..this method only applies to 5000mah 6 packs.

Easier to make your own discharger and plus I dont have heated seats
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Old 05-16-2012, 04:23 PM   #13
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You first.. Seriously though, you're being a tad bit offensive. No one said you had to agree with what I was suggesting. If you have a better way for me to do it, please share it. So you don't have anything else that draws power on your car? How about 200w worth of headlights, you have those right?
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