mikemcnair

i left my lipo plugged into the car for ~ 2 days while it was down and waiting for parts. the mamba ESC was switched off.

it was "dead" when i tried to turn it on, as in, the switch did not light up the ESC, nor did i have the ability to do anything from the Tx.

do lipo's just quit when they drop too low? i have it in the charger now, and have for ~ 1 hr(normal charge time is ~1hr) but it does not appear to me charged.

please tell me i am being parranoid. thanks in advance.

pbmax

Don't leave anything plugged into the mamba OR the quark, no matter where the switch is!! You very likely damaged the pack with extreme under-volting. Nimh can survive this, but lipo usually can't.

What kind of charger do you have?

Racing T

IF I were you, I wouldnt use that pack anymore, li-po packs handleled improperly can be very dangerous, do yourself a favor and buy a new one, I know it hurts but, is that or a possible burn hand or burn donw house, so is up to you.

Silentbob343

If dischargerd to under 3v per cell you have damaged the cells. You can attempt a recovery with some chargers, but it rarely works out long term. Some Li-poly chargers won't even charge a batt if they detect the voltage is less than 3v per cell.

pbmax

The cellpro scared me yesterday when it told me it was doing low-voltage recovery on my inferno packs. I was not pleased.... Just turned the quark back to NORMAL lipo.

Silentbob343

yikes, I have mine set to lipo high as well. or had it set...

pbmax

I hit cutoff then still drove it a little...I thought I'd charged them when apparently I hadn't. They were just below 3v / cell, so hopefully nothing too bad; I got decent power out of them today.

mikemcnair

thanks for the help.

i am running a thunderpower 3s 1320 mah. i have a "commonsense RC" charger and balancer.

the charger recognizes the battery so i think i may have a chance here. also, the balancer showed that cells 1 and 3 were higher than cell 2. so i am going to try to ballance it, and see where we go.

i know cell one had the most charge in it, so hopefully with a decent ballance i will be good to go.


i agree about buying an extra battery, and will certainly do so at the first sign of a warm pack, or any abnormal event.

mikemcnair

ok, i ran the car, after a charge, and it seamed ok. it lasted REALLY short tho. instead of ~45 mins, it was 15. also, it was cogging a bit(i have a mamba 8000 kv) and it hasn't done that in a while.

i wonder if cell # 2 is shot? is that possible?

my balancer still wants to discharge cells 1 and 3.

any ideas?

Mr. Mugen

I only did it once and brought the pack back to life. Here is a link to my experience and what I did.

http://supercubclub.proboards78.com/...ead=1173727436

mikemcnair

so far, that is EXACTLY my experience. i am gonna run the car right now(with my new lights...)

and see how long it lasts. my guess, it will be short. but the next charge a wee bit longer.

thank you Mr. Mugen!!!!!!!!

Mr. Mugen

No problem. I was able to retain about 90% of that 2200's capacity. Believe it or not I did the same thing a week ago to the same pack. This time the pack swelled up bad. I didn't even mess with it. I just cut off my dean and soaked it in salt water and tossed it. No need to try reviving a dead horse.

mikemcnair

excellent point. thanks!!!!

Mr. Mugen

Ummmm ok. Just saying it worked once. Nothing more. Peace

Silentbob343

If it is a 3S pack run it and see if you can find the problem cell or cells. You'll be able to tell by looking at the voltage. If it is only one cell giving you an issuse you can try and turn it in to a 2S pack.

mikemcnair

well, it ran well again, but appeared to last a very short time. it appears i need another pack......

mikemcnair

ok, i tried it one more time, and the car was cogging a bit. my guess: it is truly only running off of 2 cells. the balancer took forever to balance it, and then i charged it and it took 30 minutes. (roughly 1/2 the time it usaully takes)

so thanks to all of you for the help!!

Silentbob343

you can try and make it in to a 2S pack.

mikemcnair

i saw that in a post above. how? just cut the darn thing open and solder/unsolder the connections? that sounds risky, but i like it

Silentbob343

Yup, cut it open and rewire. You should be able to leave some wire so you don't have to solder directly on the tabs of the li-poly cells. Soldering to the tabs can be tricky, esp. if you've never soldered li-polys before. To be honest I'm comfortable with my soldering abilities, but I wouldn't do it. Although guys have done it just fine and salvaged their packs.

pbmax

Yeah, I'm with Silentbob343 - I'm good with a soldering iron, but I wouldn't try to re-solder one of my lipo packs. I've tried soldering those tabs before and it's tough.

mikemcnair

ok, thanks for the tips.

here is an interesting question: i know i will need to adjust my LV Cutoff on my ESC to comply with the "new" 2 cell config, but will my "commonsense RC" charger still work?

here it is.....

the title of it tells me no....

http://www.killerhobbies.com/items/b...c-3-detail.htm

so, if that is the case, i will just get a new 3 cell.

pbmax

Nope, that charger seems to be 3s only. Might be a good opportunity to invest in a decent balancing lipo charger (charges via cell taps).

Which ESC are you running? The mamba and the quark both have auto lipo cutoff these days (though the older mamba firmware revisions may not).

mikemcnair

yeah, i have a ballancer, and love it!!! i just ordered a replacement (3 cell) battery, and will try to configure the current one into 2 cells, then get another 13 dollar (2 cell) charger.

my ESC is a Mamba 25, powering the 8000kv competition X package. i do indeed have the adjustment for LVC-off and ill alter it accordingly.

i am just paranoid to open the current pack up .......

pbmax

Just write it off...the remaining cells are likely damaged anyways. That's what I'd do.... consider it an expensive lesson learned