So I just killed my lipo pack...what to do now?
 

:mad:1 :mad:1 :mad:1 :007:

That pretty much sums it up. I was out bashing around this wkend, had a gerat time and brought the truck back w/ an empty batt. Everything was turned off, but I forgot to unplug the 4S. Well, went to go charge the pack last nite, hooked it to the balancer.. nothing, its a 2*2S pack, so tried the other...nada. Um, thought balancer maybe got jacked up, plugged into charger to see voltage, ect.... 1.5V on a 2s pack....dammit. Same w. other.

What I think happened is that the BEC is not switched and so stayed on. Nothing was really drawing current, but the pack was flat, so even a few 100 mah over a couple days killed the voltage.


What should I do w/ the pack now? Its toast obviously. I've heard soaking in salt water 1st then they can be safely trashed? What a waste...

Making me consider the A123s now, as they are stupidity-resistant. How are people wiring a 5s2P pack? I can mod my batt tray slightly to accomodate a 52mm width (was made to fit a TrueRC 50mm pack,) but I'm not sure on the length. I can do ~170mm w/o change it around too much. A 4S2P would fit then, just not sure how to do a 5S2P, which is the voltage I'd really like.

???

Get yourself some FPs from Mike and you'll be ever happy.

Well the budget I'm looking at for new ones is $160, so..

My options are:
new 2x2s 6400 TrueRC packs $160
new 4S 8K True Rc packs $150
5S2P A125. less, but need charging equip (fine need something other than triton v1 anyway)
Rebuild my 2S2P+3s2P 8K True Rc pack into a 4S pack (5S too much anyway)
lastly, even saw a deal where I can get a new 10K 4s Maxamps pack for $160, but its a bit heavy. Best bang for buck tho.

I'll prolly due #3 regardless, but like I said tho, I'm thinking of going to M1 cells as I have a 1yo @ home and paranoid about burning down house w/ a lapse into idiocy.

Sorry for your loss, your not the only one, I did the same thing to my first flightpower pack it was only a 3s 1050 tho in an EDF parkflyer so not as costly a mistake. on the positive side I learnt my lesson and doublecheck that it's unpluged and I'm sure it wont happen again.

I've not used A123s but I would have thought that if you did the same thing to those they would be ruined too, can anyone confirm or refute this?

This is an older pic. of my Revo, but you can see how I mounted the 5s2p setup:
http://img.photobucket.com/albums/v1...o/IMG_4940.jpg
Each set of 2 cells that are next to each other are in parallel, so the 5 parallel groups are in series.

You can get Dewalt 36v packs on Ebay for about $110 right now. You would also need the pack building equipment. The way I made my packs is something I came up with, and is a bit complex, so I don't know if you would want to build them that way or not.

A123 cells are very safe. They don't explode or burst into flames. I've read that when they die they merely heat up, without anything else happening to them.

The pic site is blocked, but I'll check it out when I get home, but I see what you mean. I was thinking maybe a 4s pack, and then a 1S pack standing on end. Sounds a bit goofy, but it should ~fit then. Just a 3S pack is a bit too long @ 195mm (65mm*3 correct?).

Any other thoughts? How to trash lipos properly? How hard is it so rebuild a lipo pack? (my 3S+2S 8K pack above -> 1 4s pack.) Would I need to buy a new balancer tap, or could wires just be added to an existing 3S tap easily enough?

You won't be disappointed with A123 batts, they charge fast, safe, will last much longer (if that matters in R/C), user friendly, and of course a very unique performance to them. (very consistent power throughout run)

Check out the other thread on the A123's for more info on charging/chargers, there are several choices.

For reference, I am running 5s2p pack and am charging them using a lab type programmable power supply, charges them in 30 mins. As well as charging batts, the power supply can be used for many other things if you tinker at all.

You should be able to see the pic. now, I made a boo-boo.

Hook up a resistor to your Lipo pack and drain it to zero volts. Then they can be disposed of.

It wouldn't be difficult to remove two cells from your 5s2p pack. You should be able to continue using your current balancer with the 4s setup, but how the taps would be wired depends on the balancer you have.

I've liked the idea of the A123s, its just the form factor, low mah and charging irregularities have kept me from them. My pref is changing now tho.
A 30min bulletproof charge would be awesome tho. Makes getting two packs to make up the mah seem doable.

For clarity, the "5S" pack is not one pack, its a 2s and 3S pack w/ Y. It has hyperion/apache taps. I'm just not sure if wires can be inserted into the tap molex, or you have to buy them purpose-built. photobucket is blocked here, its not your link. haha least RCM is not blocked, (neither is youtube for that matter... ? wtf IT guys. )

Don't forget that A123's have a 100% usable mah rating, unlike lipo, you drain them right out, which is very abrupt when it happens. So the difference isn't so much then.

The M1's yes are bulkier than lipo, but they are very light for their size, they need to shrink them smaller is all.

Hmmm.. that is a a good point. :) You have seen they have the new 32 series cells listed on the website? Have "ultra" cells as well for better connections. Haven't seen any detailed specs yet, but thing are looking very interesting.

I did the exact same thing. The esc switch only shuts off the esc, but the servo still gets powers. I ruined 2 Maxamps 6000's, so I decided to put the nitro motor in the car. All I can say is after one cleaning and clutch rebuild, I'm switching back to BL.

Yes I have seen the new 32 series, there are no specs on them, and I have no idea what Ah rating they are. I would assume that they are larger electric car batteries, so you don't need as many smaller cells.. Yeah they have the 'HD' and the 'Ultra', each having higher power OR higher energy density compared to standard M1 chemistry. Ultra being high power, and HD being high energy.

It looks like the Ultra has 50% higher pulse power as standard M1.

It's not just the external BEC/servo, the esc has a certain leakage current inherent as soon as the battery is plugged in.

^ +1. Even with the BEC disconnected, the ESC draws power, albeit very little.

Yeah, in my case the Rx was off, so rx/servos weren't powered, just the small current drain over a few days on flat packs drained the minimal amt of pwr left and killed the batts. :( I've prolly done it before, but on charged batts it can prolly go for a very long time before it discharges enough to kill the batts.

Won't do that again

Yeah, just remember that A123's are just as likely to die if drain right to zero volts. I have drained my pack until the vehicle came to a snail crawl, charged them back up and still full power, didn't do anything.

A while back I had a post of my pack with roughly 100 cycles on it, the cell capacity was still over the rated 2300mah, it was IIRC 2375mah @ 2.0 cut-off. This is after a pack that had been used in a 10 minute discharge, as well as being accidentally shorted out, twice. IMO, they were born for R/C.

HERE is the test.

Guy named charles over at rcgroups has beaten the snot out of his A13 packs even bringing them to 0 volts and has managed to bring them back with minor performance degradation.

Well there you go!

very impressive cells, can't wait for the 1100mAh cells for 1/18 scale.

So I took apart my 3S2P 8K pack and made it into a 2S2P pack to match the other 2s2p 8K pack I had to make my 5S pack (2s+3s.)

It was a pain to take apart, as all the packs had double sided tape holding them together and I had to coax them apart. It was pulling the silver wrapper so hard on a couple I used a blade to gently score the tape so it would peel apart. Unfortunately I did get a tear in two of the cells.

It smelled a bit odd, so its what made me look, and that's when I saw one tear. The other one got cut as well as careful as I was. I sealed them back up, and did not puncture the batt, as I could see an inner lining, but does anyone know what would happen when the outer wrapper gets torn? Smelled liek hydrogen or something. I'm going to dispose of the cells regardless, I don't need them and its not worth the risk using them, but I would like to know what would happen if they are used like that.

Small rocks get under the cells/batt tray and scratch at the lining. If it ever did tear it so I couldn't see it, is that highly dangerous? I can't think it would be so much so as many ise lipos in cars and these things will just happen, but then again...:032:

Otherwise pack went together ok. Now I have 1 4S 8K pack (2*2s), which is good enough for me. I'll be looking at A123s down the line, but I'll get by on one batt for now.

Yikes, that's not good at all. Tearing the lipo packaging is very dangerous indeed, and is highly likely that it will expand/start on fire, maybe not right away, but it will over time for sure.

i did this: http://img174.imageshack.us/my.php?i...6030594of1.jpg

followed up:
http://www.rc-monster.com/forum/show...054#post110054

What exactly happened to that cell A4DTM? Looks like something hit it? That looks nasty, I take it that's the cell that died?

Well I didn't bother testing it out. They also went for a saltwater bath today too. However these packs were both fully charged, so several hours of some nice electrolysis displays. Made some cool patterns in the water w/ the salts or bubbles (hard to tell what it was, but looked like it was following the current.)

Well a sad and expensive wkend, but still have a pack, so all is good.

Well if you want to go to A123 packs anytime, HERE is a great link showing a DeWalt 36v pack being taken apart and made into other packs.

I just bought two of these packs as I am going to 7s2p pack and a Neu 1512/3D/F at 1700Kv., this pack is capable of 3000 watts.

the pinion slid off the motor shaft, until it hit the battery. threadlock fixed that problem.. I'm guessing that's the cell that's bad, because cell #4 (from the positive balance lead) is the cell that dropped to 1.8v. The cell that's damaged would either be #2, or #4, so i'm guessing it's #4, as it is slightly puffed more than the others.. meaning the other's are all wrinkly*sp, and that cell looks "filled" completely.

I left the pack to soak overnight so it can get disposed today. I looked and both packs had puffed (silver jacket was expanded.) Good to have those safely away, and I guess that solves that mystery. FWIW, the packs that went low voltage did not puff, so its reasonable to think it was due to the torn lining.

When you can smell that sweet li-poly smell it is wise to do what you did.

Yup, that's the highly unstable graphite in the cathode reacting with the anode when the SEI layer breaks down. It might just slowly puff up when you charge it... the ultimately it will expand and very high risk of it exploding, and igniting. Guess what, it's hard to put a lithium cell fire out, because the oxidizer is right in with the battery.

very true, many think putting a li-poly in an enclosed container will prevent a fire, but as you pointed out it doesn't need an external source for iginition/combustion to occur.