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View Full Version : Opinions - This pack safe to use??


flyranger
12-15-2005, 12:11 PM
I had a argument with a light pole at my local ball park yesterday (the light pole won, of course!) and all the damage to my Great Planes Lil' Poke is repairable. However, I spotted a small dimple on the corner away from the leads on my three cell Thunderpower 2100ma LiPo. No leakage or swelling (sounds like I'm describing symptoms of an STD, doesn't it?) or "sweet odor". I have been keeping it in a metal pot with a lid and it seem dormant. The "argument" occurred about 10 min into the flight so the batt is about 30% discharged. The question is: Is the batt safe to use?:confused:

hoppy
12-15-2005, 01:48 PM
I don't think anyone can give you an answer you could take to the bank. If it were mine, I would quarantine it in a firesafe location for the rest of its life. For instance, charge it outdoors and store it in a firesafe location away from other cells. Others might say they have done much more damage with no problems but who knows? It's my car/house that could be in harms way so I would take the precautions necessary to make an accidental ignition a non-event.

I'd also keep track of each cells voltage. A damaged pack may start to show voltage differences.

Unbalanced prop
12-15-2005, 01:56 PM
I agree with all the advice Hoppy suggested. Use it wisely and safely, and keep an eye or two on it. I have a couple packs with dings on them that get treated that way.

Doug

everydayflyer
12-15-2005, 02:01 PM
What hoppy said. The damaged cell(s) will most likely have reduced capacity. I had a 3S 1700 which looked slightly worse than yours and capacity was down approximately 40% after a few cycles. Very often part of the damage is not visible. Just the shock(impact) of being droped can cause internal damaged. Safety should be the primary concern.

Charles

hoppy
12-15-2005, 05:53 PM
For those of you who don't know charles, everydayflyer, he has a wealth of information on battery performance and many, many years of experience. He has tested many of the batteries on the market including ones that are on the way to the market. You can take his advice to the bank.

rcers
12-15-2005, 09:55 PM
Nope, I would not use it anymore. As Hoppy and Charles say, that is likely shot or will be soon. The outer cell is certainly most damaged and will likely drop in capacity.

Just not worth it.

Mike

flyranger
12-15-2005, 11:37 PM
OK, you've talked me into disposing of it. I've heard that I am supposed to soak it in salt water?

hoppy
12-16-2005, 01:55 AM
The idea is to slowly discharge it..... If it were mine, I'd use a lightbulb like this one from Radio Shack. http://www.radioshack.com/product/index.jsp?productId=2103318&cp=&kw=light+bulb&parentPage=search

After it is discharged, I've read that it is safe to throw away.

rcers
12-16-2005, 03:12 AM
Yep what hoppy said.....

No salt water stuff. Just chuck in when 100% discharged.

lshadow2005
05-27-2006, 04:41 AM
Charles,
Battery question ?
I have a tp 2100 mah 11.1 v lipo which has never been in a plane .
I went to program a new ESC and hookked up the batt. and motor and could not get a response from ESC .
checked batt volt and only had 4v and an ERROR on the Battery charger when I went to charge it.
I tookit back to hobby shop where I got it and they said they would tricle charge it and bring it back uo to snuff !!!
IS THAT POSSIBLE ??
thanks
Bob

redgiki
05-27-2006, 06:47 AM
Yeah, it's possible to bring it back from the "grave" of exceptionally low discharge. Some batteries handle it better than others. What you need to do is, after it's fully charged, do a discharge test to 3V per cell using something like a Great Planes Triton to verify capacity. If you are at less than 80% capacity when it drops to 3V at a 1C discharge rate, the battery is bad.

I wouldn't accept that idea from my LHS on a brand new battery, though. I would insist on a proper replacement, since it was defective. Guaranteed the lifespan is dramatically shortened.

Combine that with the fact that Thunder Power cells appear to have issues with number of charge cycles anyway (frequently less than 100 cycles to death, whereas other cells often last 400+), and there's just no way I'd accept that from my hobby store. If I'd already flown the battery and over-discharged it myself, I'd take responsibility and try to bring the pack back, but where it came that way? No way.