Lipo repair - Page 4 - RC-Monster Forums

lincpimp · 01.20.2009, 04:06 PM

Took the shrink off.

Note that the 1st cell is very puffed, and the 2nd cell is slightly puffed. Both cells are very near 0v, so they are gone. A good rule of thumb is that if a cell is puffed it is done and needs to be disposed off. If a cell is not puffed and below 3v it may be able to be recharged. I have a technique for doing that. Also if the foil covering is torn at all the cell is done and needs to be disposed of.

On this pack the 3rd and 4th cell appear to be fine, they are a bit deformed by the puffed cell pushing on them, but should be fine. I still completely disassemble the pack and indivdually test the good cells before I make them into another pack.

I have found that maxmaps does not do the best job matching their cells. So in a paralleled stiuation you may have one cell that is stronger than the other. Now the badly puffed cell in this pack is likely a weaker cell, and it was asked to discharge a bit more than it could, and thus puffed. I have seen this alot with the 3000mah cells, as they are 15c cells at best, and even a 10th scale 2wd can draw more than they can put put out.

redshift · 01.20.2009, 03:59 PM

I still can't believe MA or any other mfr would parallel cells like that. I know there are a few others, but the only truly safe way to work with that config is to charge it as a 4S and run it as 2S, but the balance tap is 2S....stupid!

Linc you should make a mattress out of all the puffy cells and make certain people sleep on said mattress- I'd pay to see it....

lincpimp · 01.20.2009, 04:14 PM

Quote:

Originally Posted by redshift

I still can't believe MA or any other mfr would parallel cells like that. I know there are a few others, but the only truly safe way to work with that config is to charge it as a 4S and run it as 2S, but the balance tap is 2S....stupid!

Linc you should make a mattress out of all the puffy cells and make certain people sleep on said mattress- I'd pay to see it....

Only prob with your method is that the balancer wire hookup would not work with the cells paralled. Now you could have 2 completely seperate packs (1p config) that had some sort of plug on the output wires to parallel them together, and then shrink the 2 packs together to have 1 larger pack. Then seperate the output wires and wire it as a 4s pack when charging. The way the cells are assembled is that 2 cells have the pos tabs attached together, and the neg tabs attached together, basically making one larger "cell". Then those larger "cells" are assembled in series for the desired voltage. So unless you seperate the cell pairs there is no way to charge them seperately.

I have run 2s packs in parallel before, and then charge them as a 4s pack with a charge adapter, it is the best way to gaurantee that the cells are all charged properly. How ever if the cells are not all matched at the factory, you may never get them to work together perfectly. The only real way to do it would be to disassemble a 4s pack and make 2 2s packs and then wire them in parallel via the output leads.

This is all a waste of time IMO, as you can get good cells up to 6000mah (enerland) and if you want more runtime just swap out batteries, keeps the weight low and that is always desired.

redshift · 01.20.2009, 04:24 PM

"This is all a waste of time IMO"

Exactly. Why overcomplicate things?

Are these the only MA packs like that, or are the 4S packs actually 8 cell?

lincpimp · 01.20.2009, 04:34 PM

Quote:

Originally Posted by redshift

"This is all a waste of time IMO"

Exactly. Why overcomplicate things?

Are these the only MA packs like that, or are the 4S packs actually 8 cell?

All of the 6000 and 8000 packs are 2p, made up of 3000 and 4000 cells, respectively.

So a 4s pack in either will have 8 cells.

Maxamps only do this cause they want some big mah numbers, and nothing they have save for the 8000 cells will run a MT in a 4s config. Their 5000 cells are worthless, my 5s 3700 poly rc 25c pack had way more punch and about the same runtime as a maxamps 5000 20c 5s pack... That was in a revo with the mech 2 speed and mech brakes with a 1512 2000kv motor geared for low 40mph range.

redshift · 01.20.2009, 04:43 PM

What a joke... no wonder they don't use clear shrink.

I know you're busy- and thanks for the info!

lincpimp · 01.20.2009, 05:06 PM

Quote:

Originally Posted by redshift

What a joke... no wonder they don't use clear shrink.

I know you're busy- and thanks for the info!

No prob, I have a pair of neu 5000 4s pack that I have to break up into 4 2s packs. I will post some pics of that process too. And some finished products so that people can see the end result.

lincpimp · 01.20.2009, 08:55 PM

Here are a few pics of a 4s pack that I broke down into 2 2s packs. Pretty straight forward, just figured you guys might want to see a finished product. I normally use 12 gauge wire and deans plugs, but I can put on any type of plug or wire there is. I prefer hyperion balance taps, but yet again, any style can be put on.

E-Revonut · 01.21.2009, 12:03 AM

Nice work linc! I'm considering sending you my Neu packs to re-wire. They come with 10ga wire that doesn't bend to well near the pack like needed in my E-REVO. Even after taking a dremel to the wire opening I still cut the insulation on the wire. For now I put the liquid electric tape over the cut, then wrapped with electric tape, and opened up the hole for them to pass through even more. I would also like hyperion taps, not a big fan of the kokam taps.

lincpimp · 01.21.2009, 12:28 AM

Quote:

Originally Posted by E-Revonut

Nice work linc! I'm considering sending you my Neu packs to re-wire. They come with 10ga wire that doesn't bend to well near the pack like needed in my E-REVO. Even after taking a dremel to the wire opening I still cut the insulation on the wire. For now I put the liquid electric tape over the cut, then wrapped with electric tape, and opened up the hole for them to pass through even more. I would also like hyperion taps, not a big fan of the kokam taps.

Sounds doable. Do you want 12 gauge wire installed? More flexible...

As for the tap swap that should be straight forward, getting the case open is usually the worst part. At least if you want it to close again!

And if it is anything like the trakpower or losi hardcase lipos, it could do with some extra cushion/packing in the case to stop the cells moving around.

E-Revonut · 01.21.2009, 12:46 AM

XP 4900mah cells, no hardcase. 1- 3s pack 1- 2s pack I think 12ga is more than adequate on my setup, no crazy gearing, less than 40MPH on 5s. Not worried about the hardcase pack I run in my crt.5

lincpimp · 01:05 AM

Ok, figured that you were cutting plastic with the dremel...

So they are soft case lipos. No prob, as long as you like black shrink wrap on them when I am done. I have the hyperion taps for 2-3s here too. So quick turnaround for ya. Do you need new connectors on the main leads, or can I swap whay is on the 10 gauge wires?

E-Revonut · 01.21.2009, 01:03 AM

Prolly be sending them in a month, I will obviouslly contact you before doing so! I already have the hyperion taps for them, I was going to do that myself making the connections outside shrink. I will remove the connectors from them before sending and clean them up and put some shrink on the bare wire ends.

lincpimp · 01.21.2009, 01:05 AM

Ok, just let me know.

rawfuls · 01.21.2009, 02:34 AM

Lincy, I have to ask, yes, I just called you lincy, but how and where do you dispose of your batteries and lipos?