Aftermarket iMiEV battery upgrade project

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nuggetgalore
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Re: Aftermarket iMiEV battery upgrade project

Post by nuggetgalore »

jonescg wrote: Tue, 28 Jan 2020, 20:20 Well only 5 pages in and I can finally say I'm starting work on Roger Groom's car. Sadly, Roger passed away last September, but his wife Pauline is still driving it and is keen to upgrade to the new high energy density cells. Car is delivered on Saturday and I've set myself a month to get it repacked with these LiYuan 60 Ah NMC cells. Expect lots of questions. From me.
Good news!
Best wishes for the project, please be careful , those compressed smoke containers are dangerous.
I want you to be alive to do my car too!
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Re: Aftermarket iMiEV battery upgrade project

Post by abenn »

Hi Chris. I'm another one in the 80km club and looking for a new battery sometime soon. Although with my new electric bike as well the 80km still does nearly all we need. I'm in Perth(Maylands) so any point offering you help to make it go quicker ? I'm an electronic engineer so know the basics but no expert on battery packs, BMS etc
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Re: Aftermarket iMiEV battery upgrade project

Post by jonescg »

Pauline dropped the iMiEV over on Saturday, so I spent this morning getting the battery out of the car.

You start by removing the front passenger seat, parting the floor coverings and removing the access cover. You pull out the service disconnect here. While you're here you can undo the cabin air inlet and push the rubber boot through.

Then you raise the car up on the hoist and remove the two access panels underneath. Check for zero volts, and then remove the cable lugs for the inverter one the driver's side, and the ChaDeMo inlet on the passenger side. Also remove the 12 V wiring connectors. Cabletie the cables out the way so the pack will clear them.
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While the car is up there, grab a breaker bar and crack the 10 x 17 mm hex bolts. Then lower the car onto a sturdy shop trolley with some blocks of wood for clearance. Remove all the bolts. Also, a bit sneaky, but you need to remove two 10 mm hex bolts on either side which form part of a bracket on the rear of the pack. I tried lifting but found something was still attached.
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Once undone you will find the last 12 V connector which will quickly be under strain if you don't disconnect it - the suction fan.
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Now that it's out I will remove the cover and carefully replace the 8-cell blocks with the new cells one by one. I can't mix the BMS boards up or it gets very confused.
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Re: Aftermarket iMiEV battery upgrade project

Post by jonescg »

Gotta say, a replacement LEV50N cell with 80 Ah would be sooooo much easier :/
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Re: Aftermarket iMiEV battery upgrade project

Post by brendon_m »

Repack the cell cases with pouch cells? The world is your oyster... With enough money anyway
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Re: Aftermarket iMiEV battery upgrade project

Post by rhills »

I'm also following along with great interest, Chris, hope it all goes well!
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Re: Aftermarket iMiEV battery upgrade project

Post by mark_hetho »

Cells of the same dimensions would really help - regardless of the capacity.
The samsung SDI 94Ah cells are not far off. Would definitely shave them down to 80Ah to get a cell the right dimensions and be really happy.
One thought a friend put to me was to construct an entirely new subframe and pack the cells in a physically convenient way, then build new bus bars, BMS wiring etc.

I'm keen to see how this project goes, but I wish it was easier for yourself (and my future self)
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Re: Aftermarket iMiEV battery upgrade project

Post by brendon_m »

On the plus side the leaf will be easier because it has a spaghetti junction bms rather than the cell top boards. You will be able to put the cells in however and just run the wires to wherever they need to go. On the down side it's easy to upgrade a leaf now by getting a later model pack and it might not be worth trying to repack one.

I'm very interested in how the imiev computer goes with the extra capacity. Whether or not it can handle over 60ah without throwing a hissy fit.
It would interesting to do the same sort of thing in an outlander phev.
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Re: Aftermarket iMiEV battery upgrade project

Post by jonescg »

mark_hetho wrote: Sun, 02 Feb 2020, 16:00 Cells of the same dimensions would really help - regardless of the capacity.
The samsung SDI 94Ah cells are not far off. Would definitely shave them down to 80Ah to get a cell the right dimensions and be really happy.
One thought a friend put to me was to construct an entirely new subframe and pack the cells in a physically convenient way, then build new bus bars, BMS wiring etc.

I'm keen to see how this project goes, but I wish it was easier for yourself (and my future self)
It would be possible to build an entirely new subframe and make it work, so long as the BMS modules and the CAN route stayed exactly the same. It's what I was originally thinking about doing in the first instance, but decided it was probably too long for someone to be without their car (the Prelude was bad enough). But yeah, no reason it can't be done, and additionally, the iMiEV is able to pull cool cabin air through the pack. Not even the Leaf does that.
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Re: Aftermarket iMiEV battery upgrade project

Post by nuggetgalore »

Thanks Chris for posting stage one.
Best wishes for a successful refit.
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Re: Aftermarket iMiEV battery upgrade project

Post by nuggetgalore »

It is a few days since the last update.
I hope everything is progressing ok.
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Re: Aftermarket iMiEV battery upgrade project

Post by jonescg »

Geez, no pressure. Only 100 iMiEV owners hanging on this thread right now!!

SO today I removed the cover and started to take a look inside.

First you have to remove the service disconnect entry point. The mastic is sticky, but once the four bolts are undone it lifts off easily.
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Good to see everything is clean and dry, and nothing seems too swollen.
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With the service disconnect, main pack positive and main pack negative show no potential.
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But once you insert the link...
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It's sitting at about 344 V. Which is 3.91 V per cell. At the time I pulled the pack out the GOM was saying 31 km remains and was sitting on about 1/3rd charged. Interesting.
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First thing to do (after removing the service disconnect link) is to take the first couple of busbars off and undo the module clamps. The plastic covers on the main terminals pop off easily and you can fit a 12 mm ring spanner in there. Once the first two busbars are off, the module can be lifted up and the BMS plug can be removed.
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After removing the covers I labelled all of the cell top terminals. I will need to mount this exact BMS module somewhere in the same location, but with remote wiring to the cell tops of the new cells. This will be a lot more complicated than I first thought, especially since cell number 1 (the most negative cell) at the opposite end of the module block.
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Re: Aftermarket iMiEV battery upgrade project

Post by jonescg »

new cell layout.jpg
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This looks to be the least worst termination arrangement for the 60 Ah prismatic cells. It allows for the modules to be terminated at the forward end, meaning a lot less copper than otherwise. Fly-wired to each cell top will make the BMS happy. The BMS should sit on top with a minimum of fuss too.
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Re: Aftermarket iMiEV battery upgrade project

Post by brendon_m »

jonescg wrote: Sat, 08 Feb 2020, 14:45 Geez, no pressure. Only 100 iMiEV owners hanging on this thread right now!!
I'll have you know there's an outlander phev in my carport that might want a battery upgrade at some point and I'm following your progress closely. So you can add the outlander owners on top of that 100
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Re: Aftermarket iMiEV battery upgrade project

Post by brendon_m »

jonescg wrote: Sat, 08 Feb 2020, 14:45 It's sitting at about 344 V. Which is 3.91 V per cell. At the time I pulled the pack out the GOM was saying 31 km remains and was sitting on about 1/3rd charged. Interesting.
I've been recording the voltages vs percentage in my outlander to try to create a bit of a graph for my NCM cells in my moke.
My readings are taken after about 1min of rest time after driving so the voltages are artificially low but 3.91V translates to roughly 50%.
Because the imiev cells have been rested properly the 3.91V would probably equate to around the 30-40% so it seems to check out (according to mitsubishi anyway).
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Re: Aftermarket iMiEV battery upgrade project

Post by jonescg »

One option is to use the existing clamping frames, but it makes securing the cells relative to each other a bit harder. Otherwise I'm looking at 3 mm plate aluminium and RHS with threaded rods. And lots of insulation between them.
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Re: Aftermarket iMiEV battery upgrade project

Post by jonescg »

Just checked and sure enough, the case of the cells is live :|

Sometimes it's consistent with the (+), sometimes it's continuous with the (-). So basically these cells will need to be packed out entirely with polyethylene so they can't touch each other, or the clamps.

Bugger.
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Re: Aftermarket iMiEV battery upgrade project

Post by brendon_m »

Not that it changes the outcome but is it actually live or just capacitance?
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Re: Aftermarket iMiEV battery upgrade project

Post by jonescg »

It's live alright - 0.01 ohms. Turned out it's just continuous between the case and battery (+).
I can get sheets of 0.8 mm thick FR4 between the cells and use 5 mm thick PE on the outer edges. Not ideal regardless.
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Re: Aftermarket iMiEV battery upgrade project

Post by nuggetgalore »

jonescg wrote: Sun, 09 Feb 2020, 11:13 Just checked and sure enough, the case of the cells is live :|

Sometimes it's consistent with the (+), sometimes it's continuous with the (-). So basically these cells will need to be packed out entirely with polyethylene so they can't touch each other, or the clamps.

Bugger.
Are you referring to the original cells or the 60Ah replacements?
Sounds very strange, especially if not consistent with either plus or minus.
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Re: Aftermarket iMiEV battery upgrade project

Post by brendon_m »

jonescg wrote: Sun, 09 Feb 2020, 11:42 It's live alright - 0.01 ohms.
So if you put a globe (or other load) from the negative terminal to the case it'll light up globe. Because that's not ideal. If its "just" the case acting as a capacitor then a short between cell cases isn't going to let all of the smoke out only drain the cell over time.
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Re: Aftermarket iMiEV battery upgrade project

Post by brendon_m »

nuggetgalore wrote: Sun, 09 Feb 2020, 17:30 especially if not consistent with either plus or minus.
He corrected it to be only positive
jonescg wrote: Sun, 09 Feb 2020, 11:42 Turned out it's just continuous between the case and battery (+).
Which is a lot less unnerving.
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Re: Aftermarket iMiEV battery upgrade project

Post by nuggetgalore »

He corrected it to be only positive
jonescg wrote: Sun, 09 Feb 2020, 11:42 Turned out it's just continuous between the case and battery (+).


Ah thanks, I missed that. Yes , a lot less unnerving!
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Re: Aftermarket iMiEV battery upgrade project

Post by jonescg »

I wonder if that's part of the reason these cells are high energy density and low cost - they forgot to include some key features :o

Yes, a lightglobe will light up between (-) and the case.
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Re: Aftermarket iMiEV battery upgrade project

Post by brendon_m »

jonescg wrote: Sun, 09 Feb 2020, 20:03 they forgot to include some key features :o
Like insulation, Don't worry that's an unnecessary expense. ;)
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