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battery cell replacement inside sheet

automixcars

Member
Jan 25, 2018
49
27
Denmark
Hallo all
I am looking for a replacement cell to install inside bad sectors in a sheet .
I have found this style . CGR18650CG 2250mAh 3.7V li-ion battery 10A
do some one know the correct spec.inside a 2.0 ess sheet??
Kind regards
Michael
 

dhrivnak

Active Member
Jan 8, 2011
4,490
3,756
NE Tennessee
Hallo all
I am looking for a replacement cell to install inside bad sectors in a sheet .
I have found this style . CGR18650CG 2250mAh 3.7V li-ion battery 10A
do some one know the correct spec.inside a 2.0 ess sheet??
Kind regards
Michael
Wow you are brave as I hear they are spot welded to a fusing wire at both ends. Way above my skill level.
 

X.l.r.8

Supporting Member
Supporting Member
Feb 18, 2018
1,523
951
Toronto/Miami
Not possible I’m afraid, your only option is to replace the brick the cell is in. It’s more than glued in. I have been wanting to get a sheet to see if a retro brick could be made using the cooking ribbon from a model s and using less cells of higher capacity to fool the car into believing it’s a stock sheet.
 

X.l.r.8

Supporting Member
Supporting Member
Feb 18, 2018
1,523
951
Toronto/Miami
It’s not just the cells next to them, but the coolant system encapsulated in the adhesive. Also the cells are not wrapped so the only feasible way I can see is disconnect and isolate the cell, drain it fully, drain it some more. Slowly and very carefully bore the cell out the brick replace a similar cell charged to the same as the rest of the brick and you can replace a fusible link easily enough. The question remains is how much room will you have before you hit the coolant passage, if you can strip the can and then ream the case away that may work.
 

automixcars

Member
Jan 25, 2018
49
27
Denmark
It’s not just the cells next to them, but the coolant system encapsulated in the adhesive. Also the cells are not wrapped so the only feasible way I can see is disconnect and isolate the cell, drain it fully, drain it some more. Slowly and very carefully bore the cell out the brick replace a similar cell charged to the same as the rest of the brick and you can replace a fusible link easily enough. The question remains is how much room will you have before you hit the coolant passage, if you can strip the can and then ream the case away that may work.
yes I know all this I have made 5 bricked roadsters come to life and I have 3 more waiting .if the the cells can be replaced (if there are maby up to 5-6 bad in a cellblock ) I think it can be done. but I am looking into installing model 3 cells inside a new design battery box and just use the same amount of KW to foul the car .but the problem are the shipping of cells from USA to me in DK we do not have damaged model 3 here for now.
 

hcsharp

Active Member
Jun 7, 2011
3,409
1,437
Vermont
Thats exactly been my thought process, as long as you don't go over the bricks mah there's no reason for the car to get upset.
There's more to it than that. The discharge curve is very different so the capacity measurements won't work. The Model 3 cells also discharge to a much lower voltage in order to get their full ah capacity. I also doubt you could fit 11 sheets of longer cells. I don't want to discourage anybody... It might still be worth a try.
 

automixcars

Member
Jan 25, 2018
49
27
Denmark
There's more to it than that. The discharge curve is very different so the capacity measurements won't work. The Model 3 cells also discharge to a much lower voltage in order to get their full ah capacity. I also doubt you could fit 11 sheets of longer cells. I don't want to discourage anybody... It might still be worth a try.
Hey
I was thinking to get some loose cells model 3 mabey 10 from ebay to do test along a normal sheet to see how it charge /heat and so on.
my idea was to fit not 11 sheets with same amount of cells but only about half because the model 3 have more mA(4400-4800) the idea was to do a capacity test of a good cell section in a original sheet and use this as a guide line.
Tesla says that all patents are open but I can not get the info from anybody the specification of the original cell only guessing
maybe it is just a stupid idea but I like a challenge :)
 

X.l.r.8

Supporting Member
Supporting Member
Feb 18, 2018
1,523
951
Toronto/Miami
When trialing a lot of 18650 cells the high mah cells (greater than 3200) degraded much much faster than the sub 3000 mah cells. I would first try a similar cell. The 3.0 needed reprogramming and I’m not sure there’s anyone around who would know how to do that anymore. Even a new pack with standard capacity would be a great starting point and a life saver to all those bricked cars at co-part.
 

Stefan T

Member
Jan 31, 2015
343
175
Sweden
I did a calculation how many 21700 cells that was possible to fit in side one sheet if the problem with 70mm high cells is solved
and what i found out was that 9x51=459 cells was realistic to put in each sheet without over pack them the area is big enough in theory to 9x53 cells but i'm not shore that is possible to do
 
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Reactions: BBone and X.l.r.8

automixcars

Member
Jan 25, 2018
49
27
Denmark
If i can get a drawing with all measurements of the sheet can i try to pack the cells in solidworks
or better a 3d model of it
Hallo Stefan
please email me at [email protected] or mms 0045 21784741
I have a battery box that is empty to measure.
the cells need to stand up not horizontal like the original and the original cooling strip from model 3 need to be used to get better cooling
I have a extra roadster I think will be the test car :)
 
  • Helpful
Reactions: dhrivnak

Tommie66

Member
Apr 30, 2019
46
3
Nj
What holds the sheet in the case other than the screws? The one sheet I’m trying to remove is loose but something else seams to be holding it in yet?
Do you need to remove the alum crossmember from the bottom of the case?
 

automixcars

Member
Jan 25, 2018
49
27
Denmark
What holds the sheet in the case other than the screws? The one sheet I’m trying to remove is loose but something else seams to be holding it in yet?
Do you need to remove the alum crossmember from the bottom of the case?
hey yes the 2 screws under the alu bar need to come of as well .remember the plugs for the bmb print cards .sometimes it is the rubber boot for the cooling tubes.(just a good idea for you .the best way to not spill cooling fluid inside the box.install small rubber blind plugs on cooling fluid tubes like the ones from brake bleed screws) there are a water level sensor print in the back of the box and it will make a fault with just one drop of cooling fluid and car will not charge.

kind regards
Michael
 

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