Making a custom battery pack for MiEV

MickeyS70 · Jan 21, 2025

Wenny Yuan said:
Haha, we customized studs and provide busbars ,spacer also available ：）

Doesn't look like these cells will fit across the CMU boards I'm afraid...

LEV50: 171mm x 44mm x 98mm
CATL93: 172mm x 42mm x 90mm
SVOLT90: 148 mm x 39mm x 102mm (short and high)

[edit] actually the CMUs are only 65mm wide, but the excess height is going to be a (mission impossible??) challenge..

stoatwblr · Jan 22, 2025

It's worth noting that both the CATL and SVOLT cells are limited to 1C charge/3C discharge whilst the original LEV50s are 2.5C charge/6C discharge

That puts the allowable currents at _about_ the same for discharge, but charging will need to be limited a little (not that I've ever seen Chademo exceed 65A even with 150kW chargers, so the existing programmed limits may be fine)

One of the things that I've been wondering about would be shoehorning LiFePO4 cells into the packs. I know that would require serious reprogramming and potentially mean a 20% reduction in peak power, however they tend to have vastly greater tolerance of charge/discharge currents as long as the low-end thermal requirements are met (ie: no charging below freezing and a pack heater probably needed) and they have longer cycle lifetimes than NMC

There's a bigger problem eyeing most of us in cold(ish) climates where road salt is used: Chassis corrosion. These are repurposed JDM cars and have fairly poor rust protection. It may not be worthwhile investing several thousand dollars in a new battery pack if the car ends up failing annual safety inspections due to rotted-out suspension mounts

What are people finding under the skirts when the battery pack is dropped out?

jray3 · Jan 23, 2025

What are people finding under the skirts when the battery pack is dropped out?

My cars here in Western Washington are pretty rust-free, but the car that spent a few winters on salty roads in Colorado was much worse, with several of the splash tray retainer bolts snapping off when I dropped the pack.

Jiminy · Jan 29, 2025

Wenny Yuan said:
Except CATL93,what other batteries are suitable for Mitsubishi imiev & outlander?
We have solution without changing the original bracket!

Your task is simple: Make an exact copy of the LEV50/LEV50N battery cell in every dimension but with newer chemistry. This includes perfectly copying the terminal base plates and 8mm terminal studs. Make it a direct swap for the stock Yuasa cells with no other parts needed. Use a chemistry with little or no silicone so swelling will be reduced at EOL. Sell IR matched sets of 93 cells (5 spares). Confirm quality with high grade equipment to measure IR and include a report with every set. Crate them up and you will get orders. $3500 per set plus sea freight.

I'm so surprised that this hasn't already been done. Seems like there are tons of generic "Catl 94Ah" cells of various dimensions close to but not including 171/44/98. Make an exact copy and you will be off to the races! I have OE Yuasa cells to send you if you need a template.

AlcidesR · Jan 29, 2025

Jiminy said:
Your task is simple: Make an exact copy of the LEV50/LEV50N battery cell in every dimension but with newer chemistry. This includes perfectly copying the terminal base plates and 8mm terminal studs. Make it a direct swap for the stock Yuasa cells with no other parts needed. Use a chemistry with little or no silicone so swelling will be reduced at EOL. Sell IR matched sets of 93 cells (5 spares). Confirm quality with high grade equipment to measure IR and include a report with every set. Crate them up and you will get orders. $3500 per set plus sea freight.

I'm so surprised that this hasn't already been done. Seems like there are tons of generic "Catl 94Ah" cells of various dimensions close to but not including 171/44/98. Make an exact copy and you will be off to the races! I have OE Yuasa cells to send you if you need a template.

that would be a cherry on top of the cake! i would order 90 cells (just in case) on the next day!
I'm still trying to find out to "fool" the CAN to make the bateries fit the spec!

CeeJay09 · Jan 30, 2025

AlcidesR said:
that would be a cherry on top of the cake! i would order 90 cells (just in case) on the next day!
I'm still trying to find out to "fool" the CAN to make the bateries fit the spec!

I ordered 8 of these SVolt cells and tested them recently. The test was between 4.1v-3.3v to measure the capacity in an imiev with no CAN bridge. the cells ranged from 68.5AH to 71AH at a constant 30A load. I am in discussion with the suppliers to have these cells fitted with lazer welded tabs that mimick the cell tabs on the imiev. I will upload the files for the 3d printing files for the spacings and any clamping methods I come up with for these cells. I hope that I can get someone to assist me with accessing the remaining capacity from 4.35v-2.75v once this is completed

CeeJay09 · Jan 30, 2025

CeeJay09 said:
I ordered 8 of these SVolt cells and tested them recently. The test was between 4.1v-3.3v to measure the capacity in an imiev with no CAN bridge. the cells ranged from 68.5AH to 71AH at a constant 30A load. I am in discussion with the suppliers to have these cells fitted with lazer welded tabs that mimick the cell tabs on the imiev. I will upload the files for the 3d printing files for the spacings and any clamping methods I come up with for these cells. I hope that I can get someone to assist me with accessing the remaining capacity from 4.35v-2.75v once this is completed

I am in the process of testing the full voltage range capacity and will post those results once complete

MickeyS70 · Jan 30, 2025

CeeJay09 said:
I hope that I can get someone to assist me with accessing the remaining capacity from 4.35v-2.75v once this is completed

There are several good reasons why EVs don’t use the full cell voltage range, safety and cell longevity to name a few…

JoeS · Jan 30, 2025

CeeJay09 said:
I ordered 8 of these SVolt cells and tested them recently. The test was between 4.1v-3.3v to measure the capacity in an imiev with no CAN bridge. the cells ranged from 68.5AH to 71AH at a constant 30A load....

Thanks for doing the tests. I, for one, would be delighted with 70Ah at 4.1v max/cell.

MickeyS70 · Jan 31, 2025

CeeJay09 said:
I am in the process of testing the full voltage range capacity and will post those results once complete

CATL93 have around 87Ah within the triplet ‘range’ using OEM recommendations.

More important than capacity imho, how are you planning to deal with the excessive height of the cells, they are fitted sideways iirc and 5x4mm (25mm worst case) of additional space might be tricky to find?

JoeS · Jan 31, 2025

JoeS said:
Thanks for doing the tests. I, for one, would be delighted with 70Ah at 4.1v max/cell.

I forgot to include "...with a form factor identical to LEV50/LEV50N"

ybpvin · Feb 20, 2025

Hello, colleagues!
I spoke with the supplier about the Svolt NMC-90F and received the specifications. Overall, the batteries seem suitable for replacement, but I'm concerned about whether the voltage will drop under load. Does anyone have any information on this?

ybpvin · Feb 20, 2025

CeeJay09 said:
I am in the process of testing the full voltage range capacity and will post those results once complete

Hello, I hope your testing is going well. I was wondering if you happen to have any videos?

Daniele Schietroma · Feb 27, 2025

The supplier replied and sent me the datasheet of the batteries, I attach everything.
The price they gave me is $25 per cell.
I'll see if I can get other quotes from other suppliers and I'll update you, if anyone already has some good suppliers to report, they are welcome.

MickeyS70 · Feb 27, 2025

Daniele Schietroma said:
The supplier replied and sent me the datasheet of the batteries.

Challenging cell dimensions aside, you will have to find a way to limit the CHAdeMON current to 30A (approx 10kWh).

According to the data sheet the 1C max charging current is only applicable when pulse charging (regen).

Operating these cells in freezing conditions is best to be avoided (unless one plans to add a battery heating system).

CeeJay09 · Feb 28, 2025

I have a full model of how I will fit the Svolt cells in the imiev, I will have them welded into 4s blocks and strapped for compression to remove the need for the imiev cages. the cell tabs welded have provision for the bms to bolt onto as well with a jig designed for the tabs to be welded on. I will update with a cost per "block" if anyone is interested in ordering it once the first one is complete and tested.
I tried adding an image but it looks like I cannot add an image here

CeeJay09 · Feb 28, 2025

MickeyS70 · Mar 2, 2025

An very interesting solution (literally thinking outside the box) from one of the members on the German forum, rather than trying to fit the replacement cells into the existing module, he strapped bigger cells together so they fit snuggly into the battery frame (picture quality isn’t great but you get the idea).

Not much details (yet) on the cells used, but they are 114Ah 3.7V and apparently just 23$/per cell (+ shipping)

https://www.goingelectric.de/forum/viewtopic.php?t=94422&start=70

paulsernine · Monday at 8:46 AM

Very interesting alternativ , thank's MickeyS70 !

The electric specs shown on the foto ( 114Ah, 3,7v, discharge 421,8wh) are exactly the same than the CATL 114Ah . See :

Price of 23$ also BTW.

-dimensions of the CATL114Ah seem to be : 148 x 102 x 52
-the lev50x are 42mm deep , compare to the 52mm of the CATL114Ah

on the foto you ve send , there is 8 cell => excluding the frame, this mean there would be suffisient room to create 8x(52-42) = 80mm .

looking at some fotos of the unmounted pack , it seem the nuts on the 2 side part are taking some space , I would have say less than 40mm , but it's a guess : has somebody an open pack to mesure the hole in the plastic floor for each pack ?

best

P

MickeyS70 · Monday at 9:53 AM

There are 3mm spacers between each of the OEM LEV50x cell, which have been omitted by this solution. Obviously that will effect cell cooling but I don’t think it’s a deal breaker…

Making a custom battery pack for MiEV

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