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-   -   Rebuilding Segway i2 battery (https://forums.segwaychat.org/showthread.php?t=36985)

shmonoff 06-09-2019 03:36 AM

Rebuilding Segway i2 battery
 
5 Attachment(s)
My recent project

shmonoff 06-09-2019 03:39 AM

5 Attachment(s)
More pictures

danielg30 06-09-2019 06:11 PM

Sent you a PM.

dorrington 06-09-2019 07:18 PM

Good stuff...

I take dead units and disassemble them.. I have made a machine to test, charge, cycle and capacity check each cell when removed from the pack...bad ones get rejected good ones get recycled..i put in 20 cells at a time,....go play golf....drink beer....come back to graded cells based on capacity...even old cells can still be usable........

dorrington 06-09-2019 07:26 PM

Just a thought for next time...

I make the parallel connections dominant in each cell group....it reduces volt drop...probably doesn't matter but I'm a bit ocd....

Nice work...and no smoke....

dorrington 06-09-2019 07:30 PM

Oops...ignore me...I've been drinking...

Looks fine....🥛🥛

Don M 06-10-2019 06:53 PM

Very interesting! What cells did you use? Where did you get them? What do they cost? What was your total cost for the rebuild?

I think if I were to 'rebuild' any, I'd be doing what Dorrington says he's doing - Start with a few red light batteries and replace only the bad cells, recycling the good ones from other batteries. My experience with old batteries is that the original cells last a very long time - I've had 2007 batteries which still give 20 miles or more range

I've had really good luck buying used batteries. I have three I2's and I've bought new(er) batteries (all 6 of them) for those machines over the past couple years for an average of about $400 each, some from private sellers, a few from eBay when I find a 'bargain' - I only buy 2014 or newer batteries. I've sold my older batteries (mostly 2006, 2007 and 2008's which were all still in working condition) for an average of about $250 each, so I've upgraded all my batteries to significantly newer ones for about $150 each. I have a spare 7th battery I'm hanging on to just for emergencies, should something happen to any of them

Don

shmonoff 06-10-2019 10:08 PM

I used same as original li-iron-po4 cells, ebay has everything
Cells cost around 400 to rebuild two batteries, so it is twice cheaper than in your case, although you didn't mess with disassembling, welding etc.
My batteries were completely dead, so I wouldn't be able to sell them
Dorrington, can you share the technology, how did you replace individual cells?
First of all, what I found - it's extremely hard to extract them out of the case and not damage some on the sides (they are glued in, heat gun helps but still brute force involved).
Next, batteries are glued together with epoxy, and very well spot welded on both sides - you definitely won't be able to reuse that metal plates, and more likely will damage cells when removing plates. But maybe Dorrington found better way.

dorrington 06-11-2019 04:31 PM

hi..

right....

i take apart the case, use a heatgun on the back of the case until its really hot(don't spend too long in one spot) the cells either fall out when inverted or use a screwdriver to gently lever (picknthebpositive end of the cell, there is a compression ridge)

once apart I desolder the old cells (having first identified the bad groups), remove the nickel plates..(i just use side cutters and peel rather than rip the nickel strip off....carefully!..) where the bad cells are at and then gently drift the cell out of its sleeve!...easy peasy..no need to split the packs...keep the insulating rings from the positive ends of the cells and make sure you only apply pressure on the circumference of the cell....eventually you have a honeycomb of glued sleeves with no cells in...lol

if i'm keeping the cells I clean both ends with a file..do not short circuit or you'll damage the file!

I then push good sleeve-less cells back in where the bad ones were and reweld with nickel strip.

I try to get a feel for the other cells capacity and try to match as far as possible too.

reassemble the pack (carefull soldering)..charge fully and then capacity test.
(I have made a dummy load and can access the bms registers..the discharge process is automated and terminates automatically...the total capacity is recorded)

so far, worst rebuild is 67%, best is 95% of original.

If i have a really bad pack i cannibalise it for good cells..this is where the automatic machine comes in to play..I de-sleeve all the cells and place them in the machine 6 or 23 at a time..and return after a day or two.check the screen to see what each cell has achieved...

my machines are a jumble of wires and 3d printed parts but they do work..

I hope this is clearer?...

shmonoff 06-11-2019 04:38 PM

Yep, thanks
This is definitely a way to save on cell cost, but from the labour perspective it is the same if not more extensive.
Would be interested to take a look at your machines! Can you post a picture?


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