Turnigy LiFEPO4 packs

[lutach]

Originally Posted by himalaya

I have experienced some issues with lipo+water. Green stain apears on the balance tab, it starts from one end and then as time goes on spreads to the other end, a very clear electro-chemical effect. Those stain will cause unstable cell voltage readings thus balance result. I have(have to )replaced two balance tabs of my 10 6S packs.

Most LiPos are shrink wrapped, once water gets into the pack it can hardly find its way out. When I opened one of my failed pack I was shocked how bad it smells and what power a tiny drop of water DOES have. At many dots the metal part of the aluminum-plastic film are gone, making the cells leak. You know the leaked electro-liquid is conductive and corrosive, making more metal film disapear, and finally make the whole pack fail. As a temperary solution I made round whole windows on my survived packs' wrap film to help water out(helps it in too, but drys much faster)

You guys don't spray a little Duralube (I love this stuff) or WD40 once in a while? I do that from time to time on my balancing connectors as I don't use them a lot. I have checked most of the lipos that did get wet and I haven't found any of the problems you mentioned. I do have most of them wrapped in fiberglass reinforced tape and others have openings on the side of them.

[suicideneil]

At the extreme end of the scale you could remove the shrink, paint on some plastidip or silicon sealant at each end of the pack, including over the base of the wires, allow it to dry a little then apply some fresh shrink wrap- it will form a water tight seal pretty well, but it does nothing to waterproof the main power connectors or the balance plugs.

If you want waterproof, go back to NimH

[suicideneil]

Err, not really.

Nimh packs are either not sealed at all, or poorly covered at best- gaps at either end of the shrink. Water goes in, corrodes not only the connecting tabs but also the metal cell casings, the the whole thing ends up looking like a rusty brown mess...

[lincpimp]

If you want to waterproof you lipos it is pretty easy. Get some plastidip in a can, ziptie the wires together, and put some clear silicone aound them (make sure it gets squished between the wires) Let the silicone dry, then dip the lipo in the plastidip. Put a couple of coats on and you will be good to go. If you leave the shrink on you can always cut it off and remove it and the plastidip.

[fastbaja5b]

Silicone, and lots of it!

[lutach]

Another player in the Life cells, but lets see if the S boys will go MA style on prices: http://www.redrc.net/2009/11/speed-p...of-life-packs/. They offer the choices I mentioned before. Looks like MA is lacking behind and have they gone a bit quiet? I'll be posting this at similar threads in here, so in advanced.....SORRY FOR SPAMMING.

[snellemin]

SPAMMER! The S boys are most likely gonna match MA in price. I'll chill with my old school A123's untill the dust settles.

[lutach]

Originally Posted by snellemin

SPAMMER! The S boys are most likely gonna match MA in price. I'll chill with my old school A123's untill the dust settles.

Where's that spammer....He should be banned .

[lincpimp]

Ok, so I got my turnigy 2s2p pack in today. Looks good, but i will give it a test in something, maybe a novak gtb with a 3.5 in a 10th 2wd buggy? That should put a load on it, geared for 60 or so...

[sikeston34m]

Originally Posted by lincpimp

Ok, so I got my turnigy 2s2p pack in today. Looks good, but i will give it a test in something, maybe a novak gtb with a 3.5 in a 10th 2wd buggy? That should put a load on it, geared for 60 or so...

That's a good test bed for it.

I think you'll see, they don't mind a big amp load at all.

My 2S2P packs went through some more testing today.

This time in an E maxx using a Novak HV Motor powered by a MM Pro.

The MM Pro is smooooooooth in sensored mode.

What I did different with testing was:

Using an AUTOMOTIVE type charger, which yields a 14.5 volt charge cutoff, I recharged the packs in series, at 20 amps!

The entire recharge took less than 20 minutes! I did monitor cell voltage with a meter while recharging.

They didn't mind this treatment at all. The packs were cold when the charge cycle started, and cold when it was done.

I was tempted to kick the charger up to 40 amps. Hmmm.......should I try it?

40 amps would be about a 9C charge rate.

go for it

[sikeston34m]

Originally Posted by Brushless Moose

go for it

I just took the E maxx out for another run a few minutes ago.

Didn't bother charging it up, since it was still partially charged from the last time.

About 10 or 12 minutes of running had it on the LVC.

I then hooked it up to the Automotive Charger again, only this time, I couldn't resist.

Bumped it up to 40 amp charge rate!

Then watching the voltage of each cell to make sure everything was going right, I noticed my home-made 16 Ga wire lead off the charger was getting pretty warm. LOL

I believe the small Ga. charger lead was why it was "only" charging at 36 amps.

The packs didn't seem to mind this at all! I can't believe it really.

From fully Dead, to fully charged took less than 10 minutes. Again, I didn't detect any heat being added from the high charge rate. Then out for another run. Same Power, Same Punch.

36 amps is 8C. They can handle it!

IF any of you guys try this, remember, the Automotive charger ONLY works if you charge 4S in series.

I checked the balance of each pack. The cells are still within .003 volts of each other. They haven't been balanced since New, only checked.

Not bad for "reject" cells huh?

[lutach]

Not bad at all for rejects. Have anyone tried it with the grade A cells from you know who?

[fastbaja5b]

Originally Posted by lutach

Not bad at all for rejects. Have anyone tried it with the grade A cells from you know who?

I'd offer to try, but I would need to take out a second mortgage on the house to buy the packs!