Yet another HK Lipo arrived with very low cell!

[Spacey]

Ok so I originally ordered 4 x 5.8ah 8Cell Turnigy 25c to 35c lipo, 2 of the packs were fine with one having a couple of low cells and the last one having a cell that was 0.5v approx on delivery.

I tried to cycle that cell and bring it back to life but it always charges and discharges quicker than the others so much as to be useless. So I order another pack which arrived to day with the last cell at 1.34Volts....all the others are at 3.84Volts!

Hobby King say that they double check each pack ...my arse! I could send it back under warranty but that would mean sending it back to China rather than the German depot I bought it from grrrr.....

 

[Ypedal]

Are you brave and stupid ?
:lol:

http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=26219&hilit=lipo+repair

* There are 3 video's in all, check page 2 of that thread for the others )

 

[Spacey]

Yes I am brave and stupid And totally up for it. I will swap out the bad cells for the good ones as I have no faith that they will send me an ok pack........ No choice really lol

 

[dogman dan]

All my bogus lipos were the same brand, c rate, 4s, and bought about the same time. Don't order more batteries from the same stock of bad packs. Change brands, or c rates or something to get the next one from a different run of packs. Or at least wait for a restock of that item.

I'm sure somebody gets paid for checking those packs on the way out. :lol:

 

[el_walto]

Do you think it would be any safer if one dropped all the Cells to 3.0V before cutting the pack apart?

 

[neptronix]

freaking hobbyking :|

Maybe cluster up the 2 bad ones and send those both..

 

[Spacey]

Well it's taken 5.794Ah pumped back into the single cell at 0.7A max charge and it is only on 4.15V which is as far as I will be charging the pack.

5.794Ah is nearly the same as the packs 5.8Ah rating to 4.2V?

Hoping the cell will be ok as I'm not sure now about cutting up the pack and getting rid of the bad cell with the good ones from the other dud packs. Yeah it pisses me off that Hobby King are not checking these before they send them, what else can I do though? I can't mix different types of lipo can I safely? These 8Cell 5.8Ah long packs are quite unique. You can't send 'damaged' Lipo's in Uk post either.

 

[neptronix]

You can mix different types of batteries in parallel groups.
They will even each other out.

This is how i get my junky lipos to work in a big pack.
But if one cell is like a 90c nanotech that got into a 25c pack, then there's no fixing that with a parallel pack..

Now what you really need are some discharge graphs to get an idea of how bad this cell is. Tell me you have an iCharger / hyperion / cellog 8s?

 

[Ricky_nz]

Well it's taken 5.794Ah pumped back into the single cell at 0.7A max charge and it is only on 4.15V which is as far as I will be charging the pack.

5.794Ah is nearly the same as the packs 5.8Ah rating to 4.2V?

Keep an eye on the recovered cells selfe discharge. I recovered both cells in a 2S 5A 20C turnigy that arrived at around <0.8V each over a year ago. After charging them slowly until above 3V then charging at 1A they recovered and worked ok but if I left that pack for a couple of weeks disconnected and then measure the cells. They had dropped in relation to another 5S pack of good cells so the self discharge was bad but they did put out the current and seemed to have pretty good capacity so I used them for >6 Months till I was ordering some more lipo.

Since I was using the pack daily it was always charged every couple of days so did not have any issues with self discharge causing imbalance but after sitting for several weeks it was necessary to rebalance the cells.

Edit: Actually it might have been 0.8V for the sum of both cells so around 0.4V each

 

[Spacey]

Neptronix: Yeah I have an i1010B+ that I can hook up to the PC. I charged the dud cell to 4.15v last night at 0.7A and this morning it was sat at 4.139v which seems about right after the usual drop hot off the charger.

I have now just done a discharge of that cell at 3A and already after only 0.6Ah the cell is sagging to 3.72v but recovers very quickly back up to over 4V if I stop the process. That seems like a LOT of voltage sag for only 3A draw, but then it is just a single cell?

I will get the cell to 3.85V in line with the rest of the pack then charge it all together using the log program.

Ricky: Yeah my last pack was like that but it goes out of balance so damn quick hitting 3.5V after use when the other 7 cells are at 3.85V, it also charges much faster than the others which is why I was hoping to replace it with this new pack....but that was dud as well

 

[Spacey]

Actually I don't think I am brave enough to attempt fixing that bad cell in the old pack....the new pack with the low cell seems to be holding its charge ok. I have the pack balanced at 4.15V and am discharging the pack down to 3.9V using the log program for the i1010B+ to see how it gets on with discharging..... so far ok.

I am discharging at the maximum 1A rate this charger can go. Looks even so far.

 

[Spacey]

 

[neptronix]

I have now just done a discharge of that cell at 3A and already after only 0.6Ah the cell is sagging to 3.72v but recovers very quickly back up to over 4V if I stop the process. That seems like a LOT of voltage sag for only 3A draw, but then it is just a single cell?

Wow. Looks like that cell in particular is a 0.5C cell .. definitely a dud that will get worse over time. Return it if you can.

 

[Spacey]

It seems to be holding up much better now, it held it's charge overnight, nowhere near as bad as the pack that arrived with two really low cells in the pack with one being approx 0.8V

That pack has been replaced with this one. I have written an email to HK explaining that I can not send the packs back for warrantee due to it being highly illegal in UK/Europe to send damaged Lipo in post... and that it is also illegal to send damaged Lipo from the German warehouse also! And that they really should actually check the voltages of the cells before they post them out like they say they do!

..... and can you lease send me a replacement for free....photo's were attached.

You never know it might work

 

[neptronix]

Haha, good luck...

Will they take non-damaged lipos? I mean, yours aren't technically damaged.. and it's not like they're gonna bust a cell meter out and check

BTW i just did lipo surgery today and i must say, it's not that bad actually. Not something i'm happy to do, but easier than first suspected.

Charged them afterwards. Nothing blew up. I'm still alive.

 

[Spacey]

Getting no joy with Hobby King so I bought a pack of 2 cells for spares and ordered yet another 8C 5.8ah pack so I will have a 17.4Ah Lipo Pack at 66V

Right now I have dremeled out the bad cell and am trying to fit the spare cell in to it lol....wish me luck.

I'll use the bad cell to power my 2 x 900Lumen Ultrafire lights.

 

[Spacey]

View attachment 3
View attachment 2View attachment 1

 

[Partycat]

Nice repair.

I received 9 Zippy 20c 6s 5000mAh packs a few weeks back, all cells were in balance. Haven't really wrung them out yet to see if they will hold. One of the cells has a corner bashed in a bit, it may be okay, but, I have it as a "spare" for now. They put all 9 of them into a cardboard box with their bubble wrap and threw it in parcel post. I would have included extra foam, all the weight popped many of the bubbles.

 

[RallySTX]

The more I read about this, the more I dread ordering from HK. If I get any bad ones, they are getting donated to another member. With only one arm, I am NOT going to try that repair! Nice work Spacey. Gotta respect a girl with big balls 8)
Brian L.