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Battery pack replacement, complete 50N pack?

Posted: Tue Jan 05, 2021 1:01 pm
by Filip
Hi all.

I own a 2011 i-MiEV with 125000km on the original traction battery, the problem i have is that 2 cells
have lost most of their capacity witch brings me Turtle-mode at acceleration even at SOC above 50%.
I like this little practical car and found a 2014 pack with 7500km, so i guess this have the LEV50N cells
and not the non N wich i have at the moment.

My plane is to swich to this newer pack, preferable would be just to swich the whole pack but i can not find any relevant
info regarding the comparability between this to packs, the old LEV50 i have at the moment and the newer LEV50N im planing to install.

Anyone have any experience with this switch? I guess i need some reprogramming of CMU-boards etc?
I am pretty comfortable with the mechanical and electrical part of the job but looking for info regarding the software parts.


Thanks
Filip

Re: Battery pack replacement, complete 50N pack?

Posted: Tue Jan 05, 2021 2:38 pm
by Don
I *think* JRay3 has done this a time or two - I'm sure he'll chime in directly

Don

Re: Battery pack replacement, complete 50N pack?

Posted: Sat Jan 09, 2021 5:56 pm
by coulomb
Filip wrote:I guess i need some reprogramming of CMU-boards etc?

The CMUs are bolted to the top of the cells inside the battery pack. So as long as you swap the whole pack over, that part of things should be fine.

The main question in my mind is whether the newer pack with newer CMUs will still talk the exact same protocol, or close enough, to satisfy the old BMU (which is outside the battery pack).

Edit: actually, thinking about it a little more, the CMUs are pretty dumb, pretty much just reporting the cell voltages and temperatures. Any difference in battery voltage versus SOC would be in the BMU, so if the cell chemistry is different enough to require different treatment by the overall battery management system, some changes to the BMU firmware would be required. The easiest way to achieve that would be to obtain a BMU from a car with an LEV50N battery. Preferably the one that the battery pack came from, if that's possible. The BMU is under the left rear seat (at least, it's there in right hand drive models).

Re: Battery pack replacement, complete 50N pack?

Posted: Mon Jan 11, 2021 1:25 pm
by jray3
Thanks for the poke, Don. I have a 2014 pack still sitting in storage, as the salvaged 2012 pack powering MR BEAN is still quite healthy, and COVID killed my travel plans for a Christmas upgrade to my mother's 2012 with the the 2014 pack. I'm betting it will work, but would be happy for a paying customer in the Seattle area to test this theory!! :mrgreen: