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My project is using a Nissan Leaf motor that I need to spin up to 10k RPM. In order for the motor to reach 10k RPM, it needs 360V nominal. In order to reach 360V, I need 400 lb worth of Leaf battery. I would love to cut that pack in half (or more), as I don't need that kind of range, and weight/space is at a premium.

I looked around at other popular battery packs, and it doesn't look like I would lose much weight with them—certainly not 200 lb. I looked into reconfiguring each Leaf module from 2s2p to 4s1p, and it looks tedious, finicky, and risky.

Any batteries I might be missing? Easier way to reconfigure Leaf batteries? Any other way to boost voltage (even if efficiency suffers)?
 

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A Chevy Volt pack will give you the voltage at about 2/3 the weight - probably less

I weighed my modules when I had my pack apart - but I can't find the numbers!

I have effectively two 7 kWh "assemblies" (3 x 2 kwh + 1 x 1 kWh) - I remember being able to pick up each of the 7 kWh assemblies they were heavy but not impossible
 

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Ya know, I eyeballed the Volt pack and it seemed like a lateral move...I thought the full pack was 360V, 400+ pounds, with 16 kWh compared to the Leaf's 24 kWh...

Did things improve from 2011? There's also mention that they're not designed for continuous output, but who knows...I pulled the specs from here:

https://endless-sphere.com/forums/viewtopic.php?f=14&t=89680

Pack: 16 kWh, 435 lb, 360V nominal, 9 modules
Module: 1.8 kWh, 48 lb, 40V nominal

Maybe there's a good 100-200 pounds of battery case to shed...?
 

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I see 45 lbs/ 2kWh module

So 16 kWh - 360 lbs

75 lbs of case, electronics, armoured baseplate - sounds about right

Each of my assemblies would be 157 lbs - sounds about right
 

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If you charge to 4.15 a cell you get 2kwh extra @ 398v for 18 kwh.but that is wobbly territory.

Cover is 20 lbs, figure 5 lbs of screws holding it together, Yabert got his down to 88 lbs by taking it apart and building new cases.
 

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Any plug-in hybrid pack is a potential candidate, since they are typically designed for the same nominal voltage as typical EVs (360V from a 96S configuration), but are smaller since less energy storage is needed (8 kWh to 16 kWh). The Chevrolet Volt is the classic example of this, of course.

While the energy density is not great, that's no accident - they are designed to meet a power density target... and you need that too, right? Even if you can live with half a Leaf pack, it is only good for 40 kW, by Nissan's standards (the stock 80 kW motor power limit appears to be imposed to protect the battery).

Various resellers offer the LG Chem modules used in the Chrysler Pacifica hybrid. Bare modules (no cooling, no external housing, no BMS) are 16S and 38 pounds each, or 228 pounds for a 360 V (nominal) and 16 kWh pack... plus all the stuff that doesn't include. This style of module uses a cold plate (in addition to the module), while the Volt and Tesla modules include internal cooling already accounted for in the module weight.

All pack weights in production EVs include substantial housings. If you think that the risks are different in an DIY project, you can do without what production vehicle designers included, and have a lighter pack. Similarly, if you think that the Pacifica modules can survive your use without active thermal management, you can try that and save the weight of a cooling system.
 

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Ya know, I eyeballed the Volt pack and it seemed like a lateral move...I thought the full pack was 360V, 400+ pounds, with 16 kWh compared to the Leaf's 24 kWh...

Did things improve from 2011? There's also mention that they're not designed for continuous output, but who knows...I pulled the specs from here:

https://endless-sphere.com/forums/viewtopic.php?f=14&t=89680

Pack: 16 kWh, 435 lb, 360V nominal, 9 modules
Module: 1.8 kWh, 48 lb, 40V nominal
It's strange to list specs for only one module, when this pack contains two different sizes of module; the image on that page shows the larger module. Neither of them has a nominal voltage of 40 V or 48 V (they are 12S and 6S).

Those are the specs (sort of) for the first-generation Volt pack. Yes, it did change for the second generation in model year 2016, from 96S3P to 96S2P with larger cells, and a different split between modules (resulting in fewer modules). The capacity increased a bit.
VOLT_BATTERY.pdf
The cell count reduction implies a reduction in the number of interleaved cooling plates (there is one for every pair of pouch cells, regardless of the electrical connections between cells), which probably accounts for the weight reduction despite the capacity increase.

No battery pack is rated for the same continuous and peak output.
 

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"I looked into reconfiguring each Leaf module from 2s2p to 4s1p, and it looks tedious, finicky, and risky."

So installing a completely different battery pack isn't?

This module mod is a piece of cake...once you get 3 or 4 under your belt, you can do it while watching TV.

You'll also come up with a more productive way to do it than the guy who obviously has shares in 3M with all the tape he uses.

I say go for it. But, there's no free lunch - you get half the rated current. Which doesn't matter that much if you're only running it for 15 or 20 sec then have a cooldown.
 

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"I looked into reconfiguring each Leaf module from 2s2p to 4s1p, and it looks tedious, finicky, and risky."



This module mod is a piece of cake...once you get 3 or 4 under your belt, you can do it while watching TV.
What method would you propose using to convert a leaf 2S2P module to a 4S1P module please ?

You give the impression that it's a trivial task ....
 
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