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-   -   Lipo repair (https://www.rc-monster.com/forum/showthread.php?t=16241)

Metallover 05.04.2009 08:34 AM

I found a great website about enerland. I don't know if this has been brought up before, bue here ya go.

http://rclovers.com/WhoWeAre.htm

It hasn't been updated in awhile....

e-mikey 05.05.2009 03:25 PM

Sent mine out today pimp. I took the liberty of removing the shrink wrap hoping I could see something obvious to fix, no luck.

Thanks.

brushlessboy16 05.06.2009 10:12 AM

Hey Linc, do you happen to still have the Hard cases from eovnu87435ds's RCM packs?

lincpimp 05.06.2009 10:22 AM

Quote:

Originally Posted by brushlessboy16 (Post 284872)
Hey Linc, do you happen to still have the Hard cases from eovnu87435ds's RCM packs?

Nope, they went with the cells. They were warped anyways.

brushlessboy16 05.06.2009 12:00 PM

Quote:

Originally Posted by lincpimp (Post 284873)
Nope, they went with the cells. They were warped anyways.

Dang.. its a whole lot easier to reform intact casings then try and fill holes for bullet connectors.

nitrostarter 05.06.2009 12:18 PM

... stupid hard-case rules. Too many chicken-shits think these lipo's are going to just blow-up from riding in the car, WIMPS!

brushlessboy16 05.06.2009 12:22 PM

Quote:

Originally Posted by nitrostarter (Post 284885)
... stupid hard-case rules. Too many chicken-shits think these lipo's are going to just blow-up from riding in the car, WIMPS!

yeah..

the nitro guys think is sooo rediculous that i run 4s.. and its funny when they jump back as you connectors spark when you plug the batts in. :)

nitrostarter 05.06.2009 12:23 PM

I love to scare them with the sparks at first. But when they see it jump out the holeshot and out of turn, they run and hide. :)

himalaya 05.07.2009 05:06 AM

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.

Hardstyle 05.07.2009 05:56 PM

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

lincpimp 05.07.2009 09:02 PM

Quote:

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.

Hmm, all I can say is to try to run the pack in a low-medium draw situation, and not remove much more than half capacity. Then charge each cell separately and see if they have discharged evenly, if so they should all have lost about the same amount of mah. I would not load the pack too much, as you may damage the weaker? cells... I will be interested to see what you come up with.

Quote:

Originally Posted by Hardstyle (Post 285258)
lincpimp, have you checked my lipos yet 2 Robbe and 2 MA?

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.

lincpimp 05.07.2009 09:05 PM

To everyone here - I am getting very busy at work, and need a breather from RC. I will be taking a break from lipo repair for a few weeks. You can still ask questions, as I will be on the forum in the evenings as always. You can also send me lipos to inspect/repair, but I will most likely not look at them for a few weeks. That said it is IMPERATIVE that you send full contact info with the lipos if you send them to me. Instructions on what you want done are always appreciated too.

Thanks to everyone who uses my "service" as the money goes back into the hobby and helps me out with my supplies, etc. Just got too much on my plate and need what little free time I have to catch up on my non rc projects.

himalaya 05.08.2009 12:37 AM

3 Attachment(s)
Here are some curves to make things clear.

http://www.rc-monster.com/forum/atta...1&d=1241755976

Have a zoom in look

http://www.rc-monster.com/forum/atta...1&d=1241755976
there are two groups of curves, cell 1/4/6 (brown/pink/dark blue) presents far higher voltage under 7A charge current, unless during charge pause period they get close. The "spikes" are 3 second charge pause every minute, you can see the "bad" cells have huge spikes compared to the good cells, reflecting much higher internal resistance.

Now the discharge characterestics, same result, the bad cells have large voltage drop under only 3.2A discharge current. the good cells(red/yellowgreen/light blue) have smoooooth curve(low voltage change when current varies) and are very close from each other, while the bad group are full of glithes and far apart front the good.
http://www.rc-monster.com/forum/atta...1&d=1241755976

lincpimp 05.08.2009 12:48 AM

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?

himalaya 05.08.2009 12:49 AM

3 Attachment(s)
a zoom in look
http://www.rc-monster.com/forum/atta...1&d=1241757569


For a comparasion, here are the curves from one of my other packs

all curves are close each other and have unique shape,
http://www.rc-monster.com/forum/atta...1&d=1241757900
http://www.rc-monster.com/forum/atta...1&d=1241757569


I am completely puzzled, what has made this difference? if long storage time harmed the pack, why only half number (3/6) gone bad while the other harf stays healthy? Any appreciatable suggestions to help me save my investment ?

Thanks guys.


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