Battery cell technical information???

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triangles

Well-known member
Joined
Aug 16, 2011
Messages
1,232
Location
Toledo, Ohio
I'm looking for information on the cells used in the FFE with the intent of evaluating the feasibility of rebuilding a FFE battery, possibly with higher energy density cells. If anyone knows where I can find information on the LG cell models used in the FFE packs and/or similar sized cells from other EVs that would be very helpful. I've also contemplated a LiFePO4 pack but I would imagine getting that to play nice with the onboard charger and other systems is probably more of a hassle than it is worth.

If anyone knows where I can get an old FFE battery preferably near northern Ohio, for dirt cheap. I'd love to get my hands on one to learn how these are put together.
 
At one point I had found one of the LG chem cells that had to be what they were using in the 5P modules. It was long ago and don't have info to offer, just the hope it can be found again.
 
Okay, so here's what we have to work with.

We know the car uses 430 cells in an 86-Series/5-Parallel arrangement for a nominal 318V

23kWh or 33.5kWh gives us ~266Wh or 400Wh per 5P group.

That works out to around 72Ah or 105Ah per cell with the 3.7V nominal voltage.

Inside the pack we see cells grouped like this:



Seeing them 5 or 10 units wide suggests that is the parallel orientation and the dual ATX type connectors suggest those are stacked 2 high, making the larger blocks 20 cells and the smaller ones 10.

5 20s and a 10 gives you 110 cells. 3 of those on the bottom for 330 and 5 more 20s on the top to get 430. That all seems to line up with the exterior dimensions of the pack.

So you're looking for an LG Chem pouch cell rated for 72 or 105Ah that is ~4" wide, ~9" long and an inch or less deep. Give or take a little.

Just having the cell capacities narrows it down a TON.

Hitting google for lg-chem 70..75-ah gets me a discussion page noting the Mach E is using LGX E71a pouch cells which are officially a 71Ah cell but suspiciously close to the 72 we'd see on the Focus. Getting pictures of the bare cells seems difficult, but I think that gets us in the neighborhood.

Aside from the possible Mach E connection, I think this same cell/group format is used in several other EV packs but with different parallel groupings. But I'm sure you can tell that those stacked "plates" make for pretty easy modular construction.

Another page I found showed pinouts for modules with larger parallel groups like 7 and 9 and they basically offer cell level taps to monitor voltage along with thermistor feeds.

Some of their other module internals: https://www.diyelectriccar.com/threads/lg-chem-battery-dissection.204331/

The E48 and the NCM811 seem to have a form factor that is about 4" wide, 12" long with the tabs folded out and about a half inch thick. Which seems to generally fit to the range we're looking at here. Seems they are focusing on OEM integration though, so bare cells and spec sheets are really hard to pin down.

If you have any leads for that, let me know.
 
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