utah300rum

iTrader: (27)

I have a few older hard lipos that have been running great. They balance fine and work fine. I ordered a few new ones and when I compared them I noticed the older ones have a very slight puff or rounded appearence vs the new.

I always balance charge....never run them too low..I only race one 5-7 minute race on a pack. I never recharge them more than once per day. Overall a pretty easy life on a battery.

They work great but just holding them side to side vs the new they have a more rounded appearance. I looked at the rest and noticed the swelling or rounded seems to be consistant with the age of the batteries. The oldest ones have the most rounded profile all the way up to the brand new ones that are perfectly flat.

I looked at a few of the batts from other guys at the track and have noticed the same thing...the newer batteries have scuffs from use on the edgesbut as they get older you see scuffs appearing in the midle of the battery as it starts to get the "rounded" profile. It seem to be the same on both hard and soft packs... regardless of brand...one guy said his soft packs were a tight fit when new (last year) and this year they are getting near impossible to get in.

I asked the LHS and they told me they were gonna go bad soon and that they must have been ran low or overheated......no way to either of those. I dont even like to leave them in my truck on race day without all the windows wide open. I am pretty frekin anal...I know guys who leave their stuff in their trucks all summer. I am too paranoid and always store my batteries indoors.

Is this normal????? anyone else notice this???? or am I just nuts

nutz4rcyktw

iTrader: (67)

I have two packs that are rounded like that and I have been running them both every week for over a year.....

They both charge great, balance without any issues, have never been overheated, and have never been run low. I can't explain it but it doesn't seem to hurt them.

bowl806

I had a 3s 5250 11.1v pack w/only about 30 or so runs on it and it was swollen; I too take good care of them. I just had the fear of it catching on fire so I discharged the thing down to 3.1v per cell. It balanced fine but it would only charge to about 4900. Got too much $$$ involved in my RC to see it go "poof." I ran 22/86 in a VXL Pede when this happened so I changed gearing to 26/86. Any comments?

slasn_48

Higher gearing will just make the motor pull more amps and run hotter.

bowl806

What do you suggest then?

brickshouse

iTrader: (7)

gear it lower, try not to run them down to cutoff, a couple older ones i have poofed when i did this....they 'swell' when they are going south...i quit using them once they swell, too much money to risk if they do decide to ignite, just the way they are....welcome to the world of lipo's

bowl806

OK Thanks! I mainly had it set up to do stree runs 50+ mph but I guess the VXL can't handle the 3s too well for speed runs-or it's an older model VXL? Since 22/86 caused this problem originally I guess it'll have to go back to 18/86. Thanks again!

SuperEk4

iTrader: (32)

Charge 1-2amp

Never set cut off below 3.2

Never gear too high

Never overtemp the Lipo max below 60 degree

If you take care of your Lipo this way they will last you a long time.

Separate race packs n bash packs.

Slight bloat is ok. Aging Lipo will also bloat.

A cheap Lipo will also will bloat faster as usually the pack is overrated.

bowl806

Thanks I got all of that except maybe the gearing. I didn't think 22/86 was too crazy w/3s VXL?

Duster_360

iTrader: (21)

Just curious, but do you re-charge your lipos after running them and leave them at full voltage until you use them the next time - ie next weekend?

utah300rum

iTrader: (27)

I usually race on Thur nights, one race per battery.....I usually just leave them that way until I have time to recharge them. I usually recharge them on Tue or Wed night. So they are at full charge for maybe a day or so. All my batts are 5000mah or higher and rarely does the charger put more than 2500mah back in unless the up the mains to 10min.It seems like the batteries are usually @ 3.8 volts per cell when the charger starts.

I hate to describe the pack as "puffed"....I have seen a pack short and really puff to twice its size before...without catching fire.

Thanks for all the responses!

SuperEk4

iTrader: (32)

What amp u charge n charger u use?

bowl806

When I first got it I'd recharge it fully. After a few runs (in time mind you) I left it alone (approx. 10.2v) after the VXL cutoff went on. I'm using a Hyperion EOSO606i charger. I think it charges at 4.75 or 5a. After I discharged it v reading is 3.1 total. Do I dare fully recharge it? I've got 2 2s 5250 packs and after cutoff goes on I don't recharge till next time. 1 is powered w/VXL and the other is MMP 4600-both in a Slash. Did I say my 3s pack is for my VXL Pede?

Duster_360

iTrader: (21)

What I'm reading on RC Groups is that leaving a lipo fully charged is somehow damaging and that damage is cumulative. I used to recharge after running them as well. I don't do that anymore, I use a voltage checker and as long as its over 3.7v/cell, I leave them until next time. Any that are too low, are charged back to storage conditions of ~3.8v/cell.

My lipos that were handled the old way are slightly puffed. My newer ones that are only fully charged just before running are not. But there's about a 2yr diff in age, so it may be too early to tell if puffing of a well maintained lipo is related to time spent in 100% charged condition or not.

There is also a generation or 2 diff in lipo mediatied up in this issue. It might be the older media is more sensitive to puffing that the latest. Again, it may be too early to tell.

turbowop

iTrader: (33)

I have a couple of Venom 5600mah 50c 2s LiPo's that have swelled a bit on me. Always have used store mode on my Hyperion EOS0702i and never treated them in any way they shouldn't be. The charger shows their internal resistance to still be pretty low and they charge, balance, and run my truck just fine. Dunno...