# Leaf battery pack as doner?



## Red Neck (Feb 1, 2013)

Or use the existing charger/BMS/battery as a whole, while at it?


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## favguy (May 2, 2008)

That may work for some, the battery as a whole is the wrong size, shape and voltage for my own needs though, I'll be configuring sets of 3 of the individual batteries together, then 16 sets in series to give a total of just over 180Ah x . 121.6v nominal.

The individual leaf batteries are really nicely made and can be stacked together easily, they are 2 series x 2 parallel in each battery to give just over 66Ah x 7.6v nominal: 










I can't see the BMS wanting to work at all outside of the Leafs integrated ECU environment though!


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## Red Neck (Feb 1, 2013)

Bypassing the BMS might be difficult.. What's inside? Cylindrical cells?


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## favguy (May 2, 2008)

There shouldn't be any BMS to bypass, it looks to be on an external circuit board. The only thing inside the box are these pouch cells:


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## Red Neck (Feb 1, 2013)

Hmm. These look like possible Li Poly batteries, which would explain premature ageing, compared to LiFePo4, as Li Poly usually have a rating of 700 cycles..

Do they have any markings on them?
How many of them are stacked together
in one pack and how many in total?

Can you measure the voltage?
Li Poly would have 3.7v nominal
and charging at about 4.2..


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## favguy (May 2, 2008)

I don't actually have any of these at the moment, the pictures are from the net, so I can't tell you any more about them.

They will last way over 700 cycles or Nissan wouldn't be able to warranty them for 8 years, but I don't know how they compare to LiFePo4 for cycle life.

The chemistry is: LiMn2O4 with LiNiO2


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## Siwastaja (Aug 1, 2012)

There is no such battery chemistry as "Li poly" or "lipo". Forget it, it's a marketing term that has lost its technical meaning. Originally, it has meant that the battery uses a polymerized solid electrolyte instead of liquid. It's a separate entity from the cathode material.

LiFePO4 can be lipo. Pouch cell can be lipo but it isn't necessarily so, but nowadays "lipo" is starting to mean just a pouch cell. And pouch cell can be of any chemistry - for example, A123 is LiFePO4.

And everything I mentioned is lithium ion.

Cathode chemistry isn't the only relevant factor in cycle and calendar life, even though LiFePO4 is generally believed to be significantly better than others in both.

"RC LIPO" cells are optimized for high energy density, high power density and low cost, which is quite a combination. This inevitably results in short life.

OEM electric car manufacturers mostly use mixed oxides as cathode materials. There are different cocktails with Co, Mn, Ni etc. Apparently, these new mixes do better than the plain old LiCo.


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## MalcolmB (Jun 10, 2008)

These look really easy to use. I like the way the cells are designed to be supported inside the cans. Just insert four rods through them and you can make any size module you want. I guess the terminals are female threaded (M6?). 

If you can really get these for the sort of price you mention I would be very interested in the not too distant future. It would be good to get a hold of one or two just to measure them up and work out the best way to use them.


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## Red Neck (Feb 1, 2013)

I probably should have written that they look like Kokam polymer cells.


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## favguy (May 2, 2008)

Hi Guys,

There is another Leaf salvage going through Copart on Monday, so I'll keep an eye on it, although, there's not much damage, so I expect it will be popular and cost too much.

The trick is to keep an eye out for one that's really bashed up, rolled, heavier frontal with chassis leg damage, or front and rear ended, these don't cost much because of the work involved from a repair point of view. The battery placement on the leaf is such that it's unlikely to be damaged even in quite heavy impacts. So it seems a great proposition as a doner.

The more I think it over, the more exited I get about it, a 24Kwh lithium pack for the cost of lead...

For measurements and specs. on the individual batteries, you can have a look here:

http://www.mynissanleaf.com/wiki/index.php?title=Battery_specs

@ Malcolm, The terminals are m6 female and yes, they look really user friendly to re-engineer for diy use. Nissan stack them using rods in the main battery box, no vents, so can be used in any orientation too...


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## rochesterricer (Jan 5, 2011)

I was wondering when I was gonna start seeing this. As factory EVs become more common, using salvaged parts from them will become cheaper than new conversion parts. We may even start seeing conversion parts tailored to adapting these parts.


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## Karter2 (Nov 17, 2011)

There is a long thread on these cells over on the ES forum, with test data and capacity checks etc..
As has been stated they are LiMn2O4 chemistry with a 3.8v nominal ( 4.2 v charged). 
Capacity test on used cells ( >700 cycles ??) showed 28Ahr when discharged to 3.5v,..with some capacity left in still before the 2.5v min is reached.


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## favguy (May 2, 2008)

Do you have a link to that at all please?


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## MalcolmB (Jun 10, 2008)

I think this is it: http://endless-sphere.com/forums/viewtopic.php?f=14&t=52162

The discharge curve looks similar to the curve for the Konion cells used in the Bosch power tool packs (also lithium manganate). The Bosch packs don't have a BMS. I've been using them for a couple of years on my electric bike and they've been very robust. The only downside is that the steeper discharge curve means that the pack feels "softer". The voltage drops off progressively with discharge, instead of plummeting at the end, as it does with lithium phosphate.


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## rochesterricer (Jan 5, 2011)

Any Mitsubishi i-Mievs being salvaged? It might be fun to experiment with their Toshiba SCiB batteries.


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## tenthousandclowns (Jun 21, 2012)

There are some good photos of taking the Leaf pack apart here.

http://autobeyours.com/2011%20Leaf%20Battery%20Pack.htm

I would guess that the BMS would be too encoded with the rest of the car to be useful to us, but that's just a guess.


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## MN Driver (Sep 29, 2009)

rochesterricer said:


> Any Mitsubishi i-Mievs being salvaged? It might be fun to experiment with their Toshiba SCiB batteries.


Ben Nelson in Wisconsin has a blog where he took apart a Hurricane Sandy saltwater flooded iMiev. Some of the cells came back and some didn't. Not sure what he's doing with the car now. He didn't know it was flooded from Sandy and thought he could salvage the car but it doesn't seem like that's the case since there is corrosion everywhere and cells that didn't recover from zero volts. From everything I've read, the US iMiev uses GS Yuasa cells and not SCiB cells.

http://300mpg.org/2013/02/17/flooded-mitsubishi-i-miev/
and
http://ecomodder.com/forum/showthread.php/bens-refurbished-mitsubishi-miev-24792-26.html


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## rochesterricer (Jan 5, 2011)

MN Driver said:


> Ben Nelson in Wisconsin has a blog where he took apart a Hurricane Sandy saltwater flooded iMiev. Some of the cells came back and some didn't. Not sure what he's doing with the car now. He didn't know it was flooded from Sandy and thought he could salvage the car but it doesn't seem like that's the case since there is corrosion everywhere and cells that didn't recover from zero volts. From everything I've read, the US iMiev uses GS Yuasa cells and not SCiB cells.
> 
> http://300mpg.org/2013/02/17/flooded-mitsubishi-i-miev/
> and
> http://ecomodder.com/forum/showthread.php/bens-refurbished-mitsubishi-miev-24792-26.html


Hmm, upon further investigation it appears that the US Mitsu uses a variation on the Lithium Manganese chemistry used in the Leaf. The other EV I remember reading had the SCiB was the Honda Fit. IIRC, those are lease only though.


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## ga2500ev (Apr 20, 2008)

I've followed the endless sphere thread. One item I've had a tough time tracking down is the continuous and pulse current ratings on the modules. The best that I've found so far is from this mynissanleaf wiki page which indicates a continuous 3C and pulse 10C maximum discharge current. So the module as configured with a nominal 66.6 Ah rating can be discharged up to 200A continuous and over 600A pulse.

It's clearly no LiFePo4 from the discharge curve. But in the ballpark of 22 cents a Wh for used modules, it looks like repurposing used Leaf modules is definitely going to be a winner in the future.

ga2500ev


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## truckguy (Feb 5, 2014)

Hi everyone I've been keeping an eye those leafs and they went from 27 or 29 leafs to 19 now most of which are in new York some have been going for a few hundred to 6k so far the recks are going for more but the flood damage are going for less. I was just wondering. I bought one of those renult battery packs from evtv even with shipping and the exchange rate it's still cheaper then what there going for now. For my conversion i need atleast another 48 moduals, and been looking at getting atleast another pack I am under the impression that the battery pack is water proof since it is placed under the car and the pack was sealed from water penetration. The renult battery pack is designed to seal to the car it several places. Just looking for feed back.


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## jddcircuit (Mar 18, 2010)

I am also wondering about those flood damaged leafs and how waterproof is the battery pack?

Jeff


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## sunworksco (Sep 8, 2008)

Fresh water is not a problem but saltwater is a big problem because it is a conductor of electricity and highly corrosive to metal.


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## jddcircuit (Mar 18, 2010)

truckguy said:


> Hi everyone I've been keeping an eye those leafs and they went from 27 or 29 leafs to 19 now most of which are in new York some have been going for a few hundred to 6k so far the recks are going for more but the flood damage are going for less. I was just wondering. I bought one of those renult battery packs from evtv even with shipping and the exchange rate it's still cheaper then what there going for now. For my conversion i need atleast another 48 moduals, and been looking at getting atleast another pack I am under the impression that the battery pack is water proof since it is placed under the car and the pack was sealed from water penetration. The renult battery pack is designed to seal to the car it several places. Just looking for feed back.


What do think the ones in NY will go for? I live 1200 miles from NY which kind of sucks. I am not sure what it will cost to transport.


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## sunworksco (Sep 8, 2008)

Beware of the batteries!
You may want to test them first.


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## lithiumlogic (Aug 24, 2011)

The first generation Leaf cells were Lithium Manganese Oxide, not sure if they've switched for the current model, which has a bit more range.

Back at the time the Leaf was conceptualised, there were only 3 Lithium chemistries in the game -

Lithium Cobalt - Tesla
Lithium Manganese Oxide - Power Tools
Lithium Iron Phosphate - DIY EV etc.

Manganese Oxide is kind of halfway between Cobalt Oxide and Iron Phosphate on the safety/capacity trade off. Iron Phosphate - very safe, but would give the Leaf an even shorter range. Cobalt Oxide - not safe enough without liquid cooling, which Nissan didn't want to bother with. Manganese Oxide is still safe enough to go air cooled but has better range than Iron Phosphate.

The drawback of this chemistry is shorter lifespan. I suspect that has something to do with full charge voltage being 4.2V, same as Cobalt chemistries, so electrolyte breaks down faster. Cobalt oxide batteries could be charged to a lower voltage level to give the same daily driving range, so would last longer.

Still, if you undercharge those Leaf batteries for daily use, and only go to 4.2V range mode rarely, you'd expect them to do OK. You could even rig up a forced air cooling system if it concerns you that much.


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## sunworksco (Sep 8, 2008)

I'm thinking about using polycarbonate dual glazed panels in between the Leaf battery modules for air circulation cooling.
Would 4volt charge be at a safe level?


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## lithiumlogic (Aug 24, 2011)

4V should be fine, I think the degradation rate increases exponentially above there, 4V is about 80% isn't it?

Active air cooling - i'm trying to think why it might be needed. Well, if you're racing and pushing higher than stock sustained power, maybe. Fast charging - well no, DIY EV chargers max out at 4kw which is nothing.


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## sunworksco (Sep 8, 2008)

Maybe the polycarbonate is not needed.


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## Karter2 (Nov 17, 2011)

> I am under the impression that the battery pack is water proof since it is placed under the car and the pack was sealed from water penetration.


 Even if the pack is well sealed, how well protected are all the other electrical contacts and systems ?
you only need one minor circuit to keep draining at low power over a few months to pull that pack down to the point of no return.
Its a blind gamble to bid for one without the opportunity to do some basic checks.


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