Ballooned LiPo's

[JayJ]

Not sure what the cause of this is so not sure were to post this, the end result was the LiPo's so I guess here's as good as any.
I killed two 2s LiPo's today with my Flux XL? They were 5000mAh 30C Turnigy's, ballooned like crazy so won't be using those again. What's the constant and peak on the HPI Blur (MMM)? Was it pulling too many amps? Gearing? Stock 2350 gearing, 20/44 but with the 39t High speed Idler gear.

Good job I have 2x 2s 5000mAh 40C and 2x 3s 5000mAh 40C coming any day now. :whistling: Don't want to run those until I resolve this and am sure it won't happen again.


Thanks for looking!

JayJ.

 

[frddyj]

first question:

did you set the LVC with the castle link, and if so, what voltage?

 

[JayJ]

Yes I have set it to 3.2v but I had only been using it for 5 minutes and the pack were almost fully charged?

Thanks frddy.

 

[frddyj]

Stock 2350 gearing, 20/44 but with the 39t High speed Idler gear.

oh, sorry i didnt read your whole first post, the 39t idler gear is most-likely your problem.

when you go from the 44t to 39t idler, your gearing it too the moon the same as if you increased your pinion by 9 teeth.

so for ease of discussion, as far as gear ratios are concerned, you basically went from 20/44 to 29/44 by changing the idler gear. That being stated, you can imagine how much it increased the work load on the motor & esc which was straining for more power at that point, which would have caused your lipos to heat up & puff.

i have a 39t idler in my flux, but 14/44 on the pinion/spur & running 5s. i wouldnt run that 39t with such a high tooth count on the pinion or such a low voltage with 4s.

 

[JayJ]

Thanks frddy, so to fix this I'm going to need to increase my cell count but lower my pinion?
What kind of spds do you get running the HS Idler and 14/44 with 5s?

 

[Slimshamis]

Like frddy said it is more than likely your 39t idler, what is the c rating on the pack and what's the burst rating? Also how warm are your packs after a run?

 

[JayJ]

Oh!

I had the LiPo's taped with electrical tape to protect them, just removed the tape and they're 20-30C.
I thought they were 30C constant but they're only 20C, ma bad and I'm sure that didn't help.
As for heat, this was the first time I've properly run the Flux since XLing it and installing the HS Idler gear, open field and the first chance of full throttle. They were hot when I pulled them from the battery boxes but didn't have my temp gun with me.

 

[Slimshamis]

Ok from what I know I run turnigys also they r definitely no hyperions or MAXAMPS that c rating is way to low what you have to do is take the burst rating and divide it by 2 and that is your constant so a 30-40c burst so really that is a 20c pack and that is the minimum you want to run in a flux. I run 2 3s turnigys and they are 35-45c and they get warm not hot and haven't had a problem I also have 2 3s turnigy nano-tech's that I run and those are 45-90c and those run cooler than the other turnigy packs I own.

 

[JayJ]

I love Hyperion LiPo's, used then before but they're so expensive!
The Turnigy's I was using were throwing out 100 Amp constant and 150 Amps burst, the Turnigy's I have coming are 40C constant so 200C constant.
I've got 2x 2s 5000mAh 40C and 2x 3s 5000mAh 40C coming, should be here tomorrow or early nxt week.
So ideally I should run 1x 2s and 1x 3s, is that right? And install a lower t pinion, 14t?

 

[frddyj]

jay, put the 44t back in.

 

[Slimshamis]

Do as frddy says he knows his stuff, IMO put the 44t idler back in unless you want to do a speed run 1 maybe 2 passes and let it cool all the way down and yes you can run a 2s and a 3s together but they have to be matching mah and c ratings.

 

[Slimshamis]

Hey jayj I sent u a pm

 

[frddyj]

yes you can run a 2s and a 3s together but they have to be matching mah and c ratings.

yes, also the same Ohms. if you get both packs from the same mfr (same cells) with different voltage but same capacity and discharge you'll be ok.

imo- omit the 39t all together unless you bring that pinion down around 13, 14.

better yet, keep stock 20/44/44 and increase the voltage to 6s if you want more speed. also, dump the turnigy's and buy a quality pack. I'm surprised that only the packs puffed and it didnt fry your esc.

 

[JayJ]

Apprciate the help frddy but I just wish HPI did a stock HD Idler Gear as that's the reason I bought the Idler and the drive gears for the Heavy Duty factor, might try a smaller pinion and see how things go.