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Old 02-21-2018, 02:41 PM   #1
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Default lipo battery questions

Hey guys. I was given an Losi 22SCT TLR, and have zero knowledge on how to charge these Lipo batteries safely.

Batteries:
Two of these in series:
Team Powers LIPO Competition Pack (TP-6200-80C-saddle)
6200mAh 80c/7.4V - SD-46Wh

Charger: Turnigy Reaktor 250W 10A 1-6S Balance Charger

I just received the charger today and am a bit nervous putting power into these for the first time. Never dealt with Lipo in the past.

I know to charge them in series. Should I just toss them in the fire bag, set up my charger to do 2S at 14.8 and not worry so much? The lipos don't have balance leads, so I'll be making a XT60 to banana plug adapter this afternoon.

Thanks.

Dan
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Old 02-21-2018, 04:55 PM   #2
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Default Re: lipo battery questions

Are you trying to run 4s in the 22SCT? That truck is not designed to take that much power. I would also assume the electronics aren't rated for 4s either. Most likely the packs are meant to run one at a time for 2s voltage. I would charge the packs at 1c (which is 6.2a in your case) as this will keep things safe. You can change them both in series if you plug the balance leads in as 2 2s packs and monitor each cells voltage during the charge cycle. I have a balance board setup for this but I prefer to charge the packs separately.
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Old 02-21-2018, 07:46 PM   #3
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Default Re: lipo battery questions

Quote:
Originally Posted by elmoracer View Post
Are you trying to run 4s in the 22SCT? That truck is not designed to take that much power. I would also assume the electronics aren't rated for 4s either. Most likely the packs are meant to run one at a time for 2s voltage. I would charge the packs at 1c (which is 6.2a in your case) as this will keep things safe. You can change them both in series if you plug the balance leads in as 2 2s packs and monitor each cells voltage during the charge cycle. I have a balance board setup for this but I prefer to charge the packs separately.
Thanks for the reply. The truck very well sorted, and has been significantly upgraded (given to me by an experienced sponsored race driver). I got a chance to run it on the limited charge it had until it started dying out, which I seem to have run it down a bit too far unfortunately. I'm getting the dreaded low voltage error on my charger in Lipo mode. Trying the NiMH charge trick, but it's reluctant to go above 7.6v (in series) at 2amps. Batteries are ice cold after 20 mins, not sure if i should just let them sit on the NiMH charge for awhile longer?

Dan
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Old 02-21-2018, 08:08 PM   #4
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Default Re: lipo battery questions

If the batteries didn't "wake-up" after a few minutes on NiMH mode they most likely are not going to. Leaving them on for an extended amount of time is just asking for trouble. If it were me, I would not risk it and just recycle the packs you have and pick up a few new packs. Then I would triple check that my low voltage cut off is set correctly on my ESC. You said that you got the car from an experienced racer but 2wd racing is limited to 2s power and a racer would have set the LVC as one of the first adjustments to the speed control. It concerns me that the ESC let you drain the battery down far enough to cause damage like that. Are the packs puffy or swollen at all? That is the first sign of a damaged LiPO. What voltage did the packs read when you started to charge them? I usually set my LVC to 3.2v/cell (6.4v for the pack after a complete run) and this has kept my packs happy for years. There are a lot of differing opinions on LiPO cutoff voltage, but this is what has worked for me.
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Old 02-21-2018, 08:39 PM   #5
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Default Re: lipo battery questions

Quote:
Originally Posted by elmoracer View Post
If the batteries didn't "wake-up" after a few minutes on NiMH mode they most likely are not going to. Leaving them on for an extended amount of time is just asking for trouble. If it were me, I would not risk it and just recycle the packs you have and pick up a few new packs. Then I would triple check that my low voltage cut off is set correctly on my ESC. You said that you got the car from an experienced racer but 2wd racing is limited to 2s power and a racer would have set the LVC as one of the first adjustments to the speed control. It concerns me that the ESC let you drain the battery down far enough to cause damage like that. Are the packs puffy or swollen at all? That is the first sign of a damaged LiPO. What voltage did the packs read when you started to charge them? I usually set my LVC to 3.2v/cell (6.4v for the pack after a complete run) and this has kept my packs happy for years. There are a lot of differing opinions on LiPO cutoff voltage, but this is what has worked for me.
It was a car he tossed together from extra parts, it was never raced, looks new actually. Trinity 10.5 motor, some red hobbyking ESC, futaba 3pk with 2.4G kit. I swapped out the stock slipper clutch with an Avid Triad mod slipper, falsely diagnosing the slipping with a loose rear diff. So, barring the battery issues, it's a neat little thing.

I measured voltage across each pack and I believe each was 3.6v. Not swollen at all, they're in a hard shell, so any swelling would be masked I'd think, until it got very bad. These are listed as 7.4v each.
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Old 02-21-2018, 08:51 PM   #6
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Default Re: lipo battery questions

A 10.5 isn't going to handle 4s without coming apart. I think those packs were meant to be used one at a time. With that said, 3.6v for a 2s is well below what LVC should have caught and most likely won't come back unfortunately. If you are going to keep using the ESC I would recommend getting a program card for it so that you can change some of the more important settings. I'm not sure how lone you've been in the hobby but with Lipo's you can't run the car until it slows like you could with NiMH or NiCad's. I'm not being condescending here but maybe someone will keep from damaging a Lipo or starting a fire by not doing that in the future.
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Old 02-21-2018, 10:14 PM   #7
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Default Re: lipo battery questions

OK. So I called my cousin (who gave me the rig) to get the lowdown on all this. He got back to me REALLY quick when I mentioned I was tryin to charge 4S. These saddle packs are apparently rated in pairs it seems, though printed that way on both packs. This would lead one to think each was 7.4v. Turns out, they are 2S together. Now that I have put an NiMH mode charge on them, they're sitting at 7.66v, so I may just run them down in the car and then bring them up on a slow 2A lipo 2S charge.

Thanks for your help, sorry for the confusion.
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Old 02-21-2018, 10:29 PM   #8
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Default Re: lipo battery questions

No worries! I hope they take a full charge for ya. Good luck with your new (to you) 22SCT, post up some pictures when you get it up and running.
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Old 02-21-2018, 11:04 PM   #9
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Default Re: lipo battery questions

Each pack, in a saddle pack setup, is one cell. If you are going to charge the two 1 cell packs as a 2S pack, you would need a charging lead something like this...
Click the image to open in full size.
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