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Inside an iMiEV's LEV50 cell

Posted: Wed, 21 Feb 2018, 11:56
by jonescg
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Interesting that they chose to use two spiral-wound electrode piles fused in parallel over one big one. It possibly fills the space better than one single winding, or the current collectors would be too thick to ultrasonically fuse.

Re: Inside an iMiEV's LEV50 cell

Posted: Wed, 21 Feb 2018, 13:07
by zzcoopej
Interesting, thanks for posting.
Is this a failed cell, and are you pulling it apart just to discover what's inside, or do you intend to modify/fix it?

Re: Inside an iMiEV's LEV50 cell

Posted: Wed, 21 Feb 2018, 13:33
by jonescg
No this cell is toast - I believe it came out of Larry or Tom's iMiEV which had the battery replaced. This is a very common way of making a prismatic cell, so nothing new under the sun here, but I have determined it would be quite easy to double the range of the iMiEV with a battery weighing less than the original. Hopefully there will be a market for non-OEM iMiEV battery upgrades soon.

Re: Inside an iMiEV's LEV50 cell

Posted: Wed, 21 Feb 2018, 13:51
by jonescg
Just crunched the numbers, and you could easily fit 27 kWh worth of battery into the iMiEV battery. You can even plug the original BMS up to it and provided it didn't get confused about the increase in capacity, have a 200 km vehicle. Cost would be not much more than the OEM battery!

Re: Inside an iMiEV's LEV50 cell

Posted: Wed, 21 Feb 2018, 13:53
by antiscab
There's probably a market now, given what it costs to buy a new 16kwh imiev battery

Re: Inside an iMiEV's LEV50 cell

Posted: Wed, 21 Feb 2018, 14:54
by T1 Terry
What chemistry do they use and how much electrolyte was left in the cell before you dissected it? It looks like they use the copper as one electrode and aluminium as the other indicating that was the metal used for each type of plate, is this correct? Winston did use this method but now seem to have gone to 2 aluminium electrodes.

T1 Terry

Re: Inside an iMiEV's LEV50 cell

Posted: Wed, 21 Feb 2018, 15:26
by jonescg
Hi Terry,
Indeed - copper is the anode, aluminium cathode. Standard for 99% of all lithium cells. This video by BMW shows how prismatic cells of this kind are made at about 5 minutes in:

And at 7 minutes you can see how they use ultrasonic welding to fuse the electrodes together before welding the can up. Electrolyte is added afterwards.
These cells were a Li-manganese chemistry. Nothing fancy: https://pushevs.com/2015/11/04/gs-yuasa ... vs-lev50n/
The later cells were a NMC anode, giving slightly better performance and heat tolerance.

There was very little free-flowing electrolyte. Most of it seemed to be constrained by the small polyethylene bag the package was places inside.

I'd be surprised if Winston went to an aluminium anode, but if they did, it would result in a substantial improvement in energy density.

Re: Inside an iMiEV's LEV50 cell

Posted: Thu, 22 Feb 2018, 10:40
by T1 Terry
I haven't destroyed one of the newer cell thankfully, so I haven't actually stripped one out to check the plate material. The things that lead me to believing they had changed the plate material to all aluminium is both the positive and negative terminals are now aluminium, not a copper negative and aluminium positive. Because the cell plates are attached using a bolt to the terminal block it would not be logical to use 2 different metals such as a copper very thin plate attached to an aluminium block because they would react with each other over a very short time and you can't get inside to clean the faces and apply more Alminox.

I've given up trying to express the plates/terminals as cathode and anode because the terms change place between charging and discharging
Try explaining this definition to the lay person as they see current flowing both in and out of the positive terminal and their eyes roll back when you try to explain anything different :lol:
Definition: The anode of a device is the terminal where current flows in from outside. The cathode of a device is the terminal where current flows out. ... By current we mean the positive conventional current. Since electrons are negatively charged, positive current flowing in is the same as electrons flowing out.

T1 Terry

Re: Inside an iMiEV's LEV50 cell

Posted: Thu, 22 Feb 2018, 12:22
by Richo
jonescg wrote:
Wed, 21 Feb 2018, 13:33
No this cell is toast - I believe it came out of Larry or Tom's iMiEV which had the battery replaced.
I thought it was out of the abandoned iMiEV. :shock:

Re: Inside an iMiEV's LEV50 cell

Posted: Thu, 22 Feb 2018, 12:55
by jonescg
Nah that was a Leaf. Wonder where it got to...

I'm keen to start building battery modules to replace the cells of an iMiEV - Might get in touch with Daniel at EV-Shop to see where Phil's old battery wound up.
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Re: Inside an iMiEV's LEV50 cell

Posted: Thu, 22 Feb 2018, 14:28
by zzcoopej
jonescg wrote:
Thu, 22 Feb 2018, 12:55
I'm keen to start building battery modules to replace the cells of an iMiEV
Sounds great, I'll be a customer when my traction dies!

There is a company in Europe that has upgraded the Outlander PHEV battery to 19.5kWh, maybe you can get some ideas from him as it uses very similar cells. https://youtu.be/BRd-o8tUVHc

Maybe you'll end up with the 180km range mentioned in that very inaccurate diagram (It also says cells are 14.8v, where that is the module voltage, oops!)

Re: Inside an iMiEV's LEV50 cell

Posted: Tue, 27 Feb 2018, 05:55
by nuggetgalore
zzcoopej wrote:
jonescg wrote:
Thu, 22 Feb 2018, 12:55
I'm keen to start building battery modules to replace the cells of an iMiEV
Sounds great, I'll be a customer when my traction dies!

There is a company in Europe that has upgraded the Outlander PHEV battery to 19.5kWh, maybe you can get some ideas from him as it uses very similar cells. https://youtu.be/BRd-o8tUVHc

Maybe you'll end up with the 180km range mentioned in that very inaccurate diagram (It also says cells are 14.8v, where that is the module voltage, oops!)
I am certainly interested too.
Yes pretty poor description of the pack.

I wonder if supercaps could replace Li cells.

http://arvio.com.au/supercapacitor-brochure

This is one installed on a forklift
https://www.youtube.com/watch?v=Rm69TFxicfM

Another thought I have is to plonk one of those in the back as a spare tank if one goes on a longer trip and recharge the traction bat when low.

[ Edit Coulomb: fixed nested quotes ]

Re: Inside an iMiEV's LEV50 cell

Posted: Tue, 27 Feb 2018, 07:34
by jonescg
Supercapacitors would not be practical for a car - they still offer 1 4 of the energy density of today's Li-ion cells. Calendar life tends to time out before cycle life anyway.

Re: Inside an iMiEV's LEV50 cell

Posted: Tue, 06 Mar 2018, 20:17
by weber
That Arvio Sirius "supercapacitor" smells like a scam. All we saw in the forklift video was a 3500 Wh 48 V battery delivering 260 A. That makes it 3500 Wh / 48 V = 73 Ah, and so 260 A is less than 4C. And we saw it being charged at a mere 80 A. Just over 1C. A 1000 A charge rate was claimed. That's only 14C.

As Chris Jones can tell you, lithium ion batteries are readily available with a 75C continuous rating. Even 90C continuous are available. Of course, at 90C, "continuous" means for 60 min/90 = 40 seconds! That's how long it would take to flatten any battery at 90C. And these Li-ion batteries have a burst rating double their continuous rating. These are "LiPo" drone batteries. They typically have a 6 month warranty and don't last more than about 200 cycles.

More on the Arvio Sirius in this thread.

Re: Inside an iMiEV's LEV50 cell

Posted: Wed, 07 Mar 2018, 06:11
by bmscott
jonescg wrote:
Tue, 27 Feb 2018, 07:34
Supercapacitors would not be practical for a car - they still offer 1 4 of the energy density of today's Li-ion cells.
I'd always thought they could be very helpful as a supplemental store of charge, though. Recoup more from deceleration, feed back into the battery pack more slowly. Or just store a bit of extra juice for acceleration, and put the main battery pack under high-drain conditions less often. Smooth out the flow, generally!

I'm guessing cost is the reason why this isn't done routinely, but that equation could change over time.

Re: Inside an iMiEV's LEV50 cell

Posted: Thu, 08 Mar 2018, 07:41
by nuggetgalore
bmscott wrote:
Wed, 07 Mar 2018, 06:11
jonescg wrote:
Tue, 27 Feb 2018, 07:34
Supercapacitors would not be practical for a car - they still offer 1 4 of the energy density of today's Li-ion cells.
I'd always thought they could be very helpful as a supplemental store of charge, though. Recoup more from deceleration, feed back into the battery pack more slowly. Or just store a bit of extra juice for acceleration, and put the main battery pack under high-drain conditions less often. Smooth out the flow, generally!

I'm guessing cost is the reason why this isn't done routinely, but that equation could change over time.
That is what I thought first up when reading about these super caps. Or as an extra jerry can of juice to cart on an extended trip.

Re: Inside an iMiEV's LEV50 cell

Posted: Thu, 08 Mar 2018, 12:32
by Richo
Nope.
For ev's supercaps don't make any sense.
Most modern lithium batteries will be able to cope with high drain, regen and give more range per $ than any cap.

Re: Inside an iMiEV's LEV50 cell

Posted: Thu, 08 Mar 2018, 13:00
by weber
I second that.

The equation has changed over time. Lithium-ion battery advances have made supercaps irrelevant.

Re: Inside an iMiEV's LEV50 cell

Posted: Thu, 08 Mar 2018, 14:27
by Rusdy
weber wrote:
Thu, 08 Mar 2018, 13:00
I second that.

The equation has changed over time. Lithium-ion battery advances have made supercaps irrelevant.
Indeedy, a while back I've calculated it. Even then supercap was irrelevant. Roughly speaking, for the same super-cap 1kWh energy addition , you can add 24kWh of lithium battery at the same volume, or 30kWh for the same weight (at 3% of the price). Old figures though.

My calc: click here

Re: Inside an iMiEV's LEV50 cell

Posted: Mon, 26 Mar 2018, 12:25
by offgridQLD
While our Imiev is still managing real wold 100km + range. The day will come when a battery replacement is required.

I think the key to a pack rebuild would be to retian the OEM quality - reliability- safty rather that shooting for all out MAX performace. Even 50% more capacity at the same weight would be a huge upgrade.

Kurt.

Re: Inside an iMiEV's LEV50 cell

Posted: Thu, 05 Apr 2018, 21:41
by jonescg
I just received my delivery of 18650 cell holders; not enough for a whole battery, but certainly enough to build a 4-cell and an 8-cell test module. I figure 24 kWh worth of high end cylindrical cells would be quite achievable with an iMiEV battery.

Re: Inside an iMiEV's LEV50 cell

Posted: Fri, 06 Apr 2018, 12:42
by Richo
Do you know of anyone who has got some real "working" general duty 18650's out of China?
I was think like 500 x 2.2Ah 5C-10C for a daily m/bike.

Re: Inside an iMiEV's LEV50 cell

Posted: Fri, 06 Apr 2018, 14:45
by jonescg
I bought about 500 x 18650 cells - Mainly Samsung 30Qs and about 100 Panasonic/Sony 18650GA cells. Quality looks to be okay but I haven't done much testing on them.
They worked out to be about $6 each, and as they were a re-seller there wasn't any price break on bulk orders.