Originally Posted by himalaya (Post 285094)

Lincpimp I need a LiPo expert's help.

I bought a Hyperion pack from a stock clearance sale, really a great deal. You know Hyperion is busy introducing their new G3 and trying to close out the old Enerland based packs. The pack is brand new but may have been in store for some time period, I found the pack has problem in cell matching:

Pack: HP-LVX4350-6S, 25~40C 4350mAh
I logged the charge/discharge curve using a EOS0720i hooked to my pc and found
cell 2\3\5 has an internal resistance of about 3mΩ
cell 1\4\6 has an internal resistance of over 15mΩ
in other words, my 6S pack has 3 good 25C cells and 3 poor 5C cell mixed together.
I figured this by calculating the voltage drop during charge pause(3 seconds every minute) and the voltage rise during discharge pause(3 seconds every minute), with same result.

the cells doesn't show too much difference in capacity, all around 3950mAh(set discharge threshold 3.0V/cell) which is obviously 10% lower than it's expected to be(4350mAh).

So my questions are:
* is this problem due to long storage time ? capacity loss and IR increase.
* is there any way I can "activate" the bad cells to improve the IR ? something like high current impact\ slight overcharge/overdischarge or heat/freeze the pack?

Thanks in advance.

Originally Posted by Hardstyle (Post 285258)

lincpimp, have you checked my lipos yet 2 Robbe and 2 MA?

Originally Posted by lincpimp (Post 285344)

Just found them in a box next to the desk so I will take a look at them tomorrow and get back to you. Sorry about the delay, been really busy.

Originally Posted by Hardstyle (Post 285456)

Ok no prob. Take your time. Thanks

Originally Posted by Arct1k (Post 285527)

Linc thanks ordered the connector...

Originally Posted by lincpimp (Post 285523)

Took a quick look at your lipos just now Hardstyle.

Seems like one of the robbe lipos is a bit out of balance. The other seems ok. Did you fully charge.balance them before you sent them to me?

One of the maxamps lipos has a small amount of damage to it on the end. Otherwise they seem to be hold voltage reasonably well. What did you sue them in? Did they puff on you a bit under load?

Originally Posted by Hardstyle (Post 285534)

You said not to charge them before sending them so I didn't. I have stored them always fully charged and balanced. There's now about half years iirc from charging them.

Robbe lipos swelled quite much when I used them in my boat about 2 years ago. Haven't used them since, just charged them time to time.

Same thing twith MA lipos, both puffed. The other one which has electrical tape on it puffed more. And last time I test it it puffed again, but not so much was using it parallel 16000mah 11.1V

But thats odd you didn't notice anything else than miss balancing in the cells..

Try pressing that Ma lipo where's electrical tape, does it feel a little soft to you?

You can test drive them if you like or got time.

But if you can't find anything to fix with them you can sell them and split the moneys or something.. But I have seen my own eyes all of them puffing and only the MA lipos I have used in extreamely rare cases after that. Puffing I don't mean it has swelled to a balloon but so that it is noticeable..

Hope you get something from that :tongue:

Edit:.
Puffing was the reason to move on A123 batterys, but now Im thinking trying lipos again, I think Im old enough and learned my lesson :mdr::mdr:

Originally Posted by Hardstyle (Post 285537)

Have to be honest the robbe lipos are completely my fault, was new on the lipos/brushless stuff. I used them parallel in a 51" long boat with 6xl bk motor and with the biggest "spoon" which I could fit to the axle. Stupid huh, yes. But before that I had 4 of these packs and used them as a big 2 x 22,2V 4200 pack in parallel and of course with that 6xl motor. Very stupid, yes.. The other 2 packs died very oddly, no swelling or anything, they just go quiet. Maybe some solders joints melted, dunno. They did go for inspection to robbe, but didn't hear anything after that.

Originally Posted by nitrostarter (Post 285545)

Throw a BIG Neu in the boat and call it a day! 12s2p power, she's be a brute!!!

Originally Posted by Hardstyle (Post 285546)

Yeah! Would be sweet. And nowadays plane controllers won't cost a fortune should be much cheaper to get it running than a few years ago.

But I dunno gasoline would be nice too, get more running time. But then I don't know much about them.

Originally Posted by nitrostarter (Post 285556)

Yeah, anyhting over 40mph, you'll need Neu or Lehner power on 10s2p minimum. Or a nice gas motor.

Stock Zenoah 26cc with a 257carb will push that hull 50-53mph with a nice prop. And you can get this Zen on ebay for $205 shipped.

Originally Posted by lincpimp (Post 285554)

I think a kb 45 xl motor on 10-12s 2p would be good.

Turnigy have a HV watercooled boat esc on hobby city : http://www.hobbycity.com/hobbycity/s...hless_Boat_ESC

Pair that with this motor : http://www.hobbycity.com/hobbycity/s...hless_Inrunner

And run a pair of these lipos in series : http://www.hobbycity.com/hobbycity/s...idProduct=7300

That combo should be good for 4+ hp... Not sure how fast it would get that boat going, maybe 35-40mph.

Originally Posted by lincpimp (Post 285428)

Well, it certainly seems like those 3 cells are not performing very well. You should not have that much variance between cells. I doubt that they will do very well during a run... Not sure what to tell you to do, can you send the pack back?

Originally Posted by rawfuls (Post 286399)

Wow, look at the solder joint with the positive red wire...
Weak, hope you fixed that before you reshrunk it?

Linc, do you have anymore hard cases you can toss some Zippy's in?

Originally Posted by rawfuls (Post 286405)

Go figures.

Mike told me to just switch all my lipos, and leave the NiMH's current.

I only have 6cells, that's it.

And lipos, I have a GT ESC from HPI and the KD 700Non-HO and a TrueRC 2 Cell 5000mAh, and nothing melted... yet.

So, just to compensate, I'm just going to switch all my lipos, and my esc plugs to the real deans, and leave everything else the way it is.

Good idea? Or just plain stupid?

Originally Posted by lincpimp (Post 286409)

Good connectors are a must. I have seen the pseudo deans crap out... Real deans do perform better.