Future Battery Replacement - A Better Battery?

[Benjamin Nead]

Thanks for your reply, Don

Yes, I actually joined here back in 2011 to quickly comment on the interior appointments
of the then-new North American i-MiEV. Hopefully, you’ll be hearing from me on a more
regular basis from this point forward. No way of really knowing way back then that this
would be the EV I would be focusing on now.

And, yes, fingers crossed regarding my upcoming i-MiEV purchase attempt. I’ve heard from
others regarding difficulties on this front. Never underestimate the intransigence and quirkiness
of auto dealers and realtors! The good news is that I’m now regularly seeing reasonably priced
used i-MiEVs pop up on the online listings, as so many of the leased EVs from the 2011-12
time period are now heading back to the dealer’s lots. So, if not my friends vehicle, I’ll be on
the hunt for another used i-MiEV. We’ll see what plays out this fall.

In regards to batteries: I was basically thinking out loud here in my post. What got me started
was realizing that it would be simply impossible to put thirty 18650s inside a box the size of
a LEV50 battery and then wondering what would really work along those lines. I’m not about
to embark on a tear-down in a vehicle with plenty of warranty time left on a well-functioning
pack and with cell capacity present just to say I did it. That sort of craziness is something I hopefully
got out of my system long ago.

But what does happen in, say, 2022, when any number of i-MiEV batteries begin to falter under
normal wear and tear, with warranties long expired and replacement LEV50s possibly being long
unavailable? As you have said, much can happen between now and then. Pondering the possibilities
now of what could be possible then might not be unwise.

And, to clarify, I’m more concerned about what will happen with dead or dying packs to preserve
the life of an otherwise perfectly good vehicle, as opposed to wiring up an add-on range extender
into a well functioning i-MiEV in the near term. Part of the appeal of the i-MiEV for me is the
generous cargo space when both rear seats are folded down. The idea of having a big black box
constantly present back there with cells doing nothing more than giving me an extra 15 or 20
miles for a rare long trip sort of ruins that.

I am familiar, though, with the concept of integrating disparate cell types and a supplementary
“spoof” circuit into the existing system. I’ve seen this done successfully with a Prius (Plug-In Supply’s
conversion kit,) where a pack of Headway LiFoPO4s interact seamlessly with the Toyota’s stock NiMH
pack and turns the car into a plug-in hybrid.

Likewise, I’m also witnessing an ongoing restoration of a rather rare 1999 Ford Ranger EV
(club member project,) where the essentially fried - and very large - NiMH pack got dropped,
the shell pried open and the old cells finally getting discarded (the original plan was to individually
cycle the vintage NiMH cells, but that didn’t work out.) New Calb 100Ah LiFePO4 units now live in
the vintage shell and are in the process of being wired together as we speak. This NiMH-to-LiFePO4
conversion is requiring a new BMS to supplement the old stock one and a custom circuit box being
wired between them in “spoof” fashion, In addition to all of this inside the pack, a new charger
replacing the old one now resides underneath the hood.

It’s rather crazy stuff to contemplate today, since there are not that many 17 year old EVs out there
right now in need of an upgraded battery pack. But this is going to change over the next few years
with stock EVs beginning to proliferate now.

[Benjamin Nead]

Saw this optimistic report about triple the Yuasa battery in another iMiev forum post:

http://www.electric-vehiclenews.com/201 ... m-ion.html

Thanks, Phximiev . . .

I'm one of those rare birds who actually likes to hear about new battery developments. Who to say if
this is going to be GS Yuasa drop-in replacement for the LEV50 or not (same form factor, though, with
the terminals along the long narrow edge,) but it's good news that they are looking ahead.

Lithium sulfur is an interesting one. A couple minute's walk from my workplace at the University of Arizona
is the Chemistry Department's lab, where they're conducting research into lithium sulfur cells. I was lucky
enough to get a private tour with a few other local electric car geeks a couple years ago . . .

http://www.sciencedaily.com/releases/2013/04/130414193441.htm

The big challenge with LiS, apparently, is cycle life. Early iterations could only recharge a hundred or so times.
Now, they're upwards to a thousand cycles or so and beyond. Google "lithium sulfur" and you'll
note a lot of different labs are working on this.

[DonDakin]

So I started toying with the 18650 cells also.

In a loose configuration I got 24 in a lev-50 box. At 3 AH per cell that's 72 AH or about 44 % more then a stock imiev about 23KHW. Also the weight would be 44.6 g *24 or 1.07 KG about 38 % lighter then stock.
If the battery could support 2C discharge which is very reasonable that would not be too bad.....

http://imgur.com/a/SOIo4

Don.....

[JoeS]

So I started toying with the 18650 cells also. In a loose configuration I got 24 in a lev-50 box. ...

I didn't have a feel for the LEV-50 size. This puts an interesting spin on everything. Looking promising…

Arbitrarily finding this Panasonic 18650B spec:
http://www.batteryspace.com/hi-power-panasonic-lithium-18650-rechargeable-cell-3-6v-3400mah-12-24wh---ncr18650b-0-93---un-38-3-passed.aspx

Didn't see whether this cell has a built-in fusible link or not.

The maximum rated discharge current is 6.8A
6.8A * 24 cells = 163.2A, which is just about the maximum the i-MiEV draws, so that's OK.

The charging and discharged voltage and current characteristics are within our lev-50 parameters.

If the form factor was to be the same we would thus have a bolt-in replacement with no BMS changes needed.

Let's arbitrarily say the 18650 price is $5/cell

24 * 88 * $5 = $10,560

No wonder Elon Musk is working at reducing the cell unit cost.

What if someone wants to go into business in five years rebuilding i-MiEV packs...

Let's say in five years the price will drop to $0.50/cell ($1056/pack), and let's say these cells could be interconnected and put into a cost-effective LEV-50-size package... methinks the labor and shipping costs might make this concept prohibitive at the pack level. Nevertheless, for us hands-on types who could rebuild our packs ourselves, how much would we be willing to pay for the guts of a 23kWh replacement pack for our i-MiEV?

[Phximiev]

Ok, found a new page for Mitsubishi:

http://www.gs-yuasa.com/us/topics/index.html

And found these on the site:

A battery announcement: http://www.gs-yuasa.com/us/topics/pdf/20150303e.pdf

and a Tesla Powerwall type of thingy: http://www.gs-yuasa.com/us/topics/pdf/20150127e.pdf

Quite interesting.

[tigger19687]

What about heat ? If you pack them all in there, is there enough to allow for all the other stuff and heat exchange ?

[jray3]

Ok, found a new page for Mitsubishi:
http://www.gs-yuasa.com/us/topics/index.html
And found these on the site:
A battery announcement: http://www.gs-yuasa.com/us/topics/pdf/20150303e.pdf
and a Tesla Powerwall type of thingy: http://www.gs-yuasa.com/us/topics/pdf/20150127e.pdf
Quite interesting.

THX Phx!

In a parallel vein, I ran a few numbers given the bottom price of a used i-MiEV down around $6500 now, while good used LEAFS are now down near $12k, and a collision-salvage LEAF can hardly be had for less than $6k!? Just pricing the batteries, that's $406/kWh for i-MiEV and $500/kWh for a used LEAF (generously assuming that the used LEAF still has 24 kWh). The price for salvaged LEAF packs alone from Hybrid Auto Center is now at $271/kWh and up.

http://www.hybridautocenter.com/HAC4/in ... Itemid=605

How's that compare? Well, with new CALB cells still around $1.30/Ah, that's about $481/kWh for new, naked cells, versus $406 for used cells with a good car wrapped around them.

[Don]

I am really hoping that my gamble plays out, that when the OEM battery pack goes out, i will be able to replace it with something that will allow a longer range. My hope is that there will be some aftermarketer that will see value in making higher density packs for older leafs and mievs and keep them going.

Possibly, but I fear the market may be too small for anyone to offer a larger pack designed to fit an iMiEV. There weren't all that many sold to begin with and the number of owners with an 8 or 10 year old car with 100K on it willing to shell out several thousand dollars for a new battery pack may be so small it wouldn't make sense for anyone to tool up to make new packs specifically to fit it

I would ask you how many cars you've bought that you're still driving ten years later, but I've actually done that half a dozen times already, so you might actually still be driving your car come 2022 - I hope one or both of mine will still be running then, but at our going rate, neither of them will have 100K on them by then

Don

[PV1]

Doing some calculations, and given the size of the LEV50(n) cells, a box with the same dimensions can fit roughly 80 Ah of 18650 cells, boosting the range from 62 to 100 miles. I would imagine someone would build custom packs to keep these older EVs on the road. Whether or not the owner would pay to have a battery re-packed is less likely, but assembling large cells with 18650 cells should be pretty straightforward, albeit with all cells in parallel, not series (each group of cells are wired in series, though). The 18650 cell is quite capable.

I'm having trouble keeping my pack cool with this heat wave these last couple of days. The car, only driven 35 miles all weekend, has a pack temp of 93 degrees F. Can't do much long range driving this week.

[zzcoopej]

assembling large cells with 18650 cells should be pretty straightforward, albeit with all cells in parallel, not series (each group of cells are wired in series, though). The 18650 cell is quite capable.

There is a company in Sweden called Vtech Tuning who have disassembled an Outlander PHEV battery pack (very similar to iMiEV one) and are planning to replace the contents with 18650's. Their calculation was that it would give a 50% increase in range. Not sure their progress, I think the biggest issue will be tricking the BMS into still charging it, considering all the voltage and temperature sensors inside the pack.