Who has the current highest pack energy density in production?

[dpeilow]

Piecing together anecdotal evidence, it seems that the 100D pack is at 169 or 170 Wh/kg.

- Is that right and can anyone confirm it with a source?

- Is there anyone else out there with a production pack that beats it?

 

[renim]

Kia Soul EV is 160Wh/kg https://avt.inl.gov/sites/default/files/pdf/fsev/fact2015kiasoulev.pdf
LEAF 60kWh will be close to double the pack weight density of the 30kWh version (identical footprint, but differing side profile)

 

[WarpedOne]

Pack energy density is a poorly defined term.

Some cells include fuses, other do not. Some cells have strong shields, others have cells with weaker shields and stronger pack enclosures.
Some packs include liquid cooling, others do not, some packs are structural members (and are hence stronger and heavier), others are not and are thus lighter.

It boils down to pack energy density being a nonsense term.
What it matters is car range, price, capacity degradation, pack safety etc.
Unfortunately these cannot be expressed with a single number, so people tend to use meaningless numbers like pack energy density.

 

[renim]

pretty much all packs are structural, if the NVH eigenvalues change significantly *and they do, then the packs are structural.

but some include greater armouring, some require cooling, etc etc

 

[WarpedOne]

"Require" is not the same as "include".
Leaf pretty much requires (active / liquid) cooling but is not included. None require heating in Florida, but some still include it.
These are engineering decisions that influence the quality, price etc of the car but also its battery pack energy density.

 

[dpeilow]

Yeah thanks for pointing this out but I just need a quoted number. I'm aware of the implications of the pack being structural, auxiliary systems etc.


OK attempting to answer this myself.

The 85 kWh pack was 544 kg for 7104 cells ( Tesla Model S ) and if the cells were 46g each it means the cells are 327 kg of the total.

It was reported that the 90 kWh pack's cells are 48 g each (source?) giving 341 kg total.

So we have 14 kg difference. Added to the 45 kg difference between the P90D and P100D shown in the manual means the 100 kWh weighs 59 kg extra over the 85 kWh pack.

wk057's teardown found the pack has 102400 Wh, so with 603 kg that's 169.8 Wh/kg.


The accuracy of this estimate depends on the exact cell weight of course. One other issue is that the mass of the 85 kWh pack quoted on that site above references wikipedia, which then just has a circular reference back to the same site.

 

[ecarfan]

I find that when discussing the "energy density" of an EV battery pack it is more useful to consider that value in regards to the cells and not to the pack.

 

[apacheguy]

The cells in the 90 are the same as 100 so from this perspective they have the same density.

 

[dpeilow]

I need the pack density...

 

[dpeilow]

Kia Soul EV is 160Wh/kg https://avt.inl.gov/sites/default/files/pdf/fsev/fact2015kiasoulev.pdf
LEAF 60kWh will be close to double the pack weight density of the 30kWh version (identical footprint, but differing side profile)

Hmm. This differs wildly from http://www.kia.com/content/dam/kwcm...v/specification/kia-soul-ev-specification.pdf

But there is reason not to believe that also.

 

[diesel]

The cells in the 90 are the same as 100 so from this perspective they have the same density.

If you are referring to cell density then yes, but if the 100 pack has the same volume as the 90 pack (which it does) then the pack density is obviously higher on the 100.

 

[Rashomon]

Alta Motors. 5.8 kWh, 68 pounds for the pack.

 

[dpeilow]

Technology and Design Information

Actually it's even higher - 185 Wh/kg - but 5.8 kWh / 30.8 kg actually is 188 Wh/kg


Do we know what chemistry they are using?

 

[Rashomon]

Alta uses 18650s from one of the major suppliers, nothing particularly unusual. They haven't talked about the chemistry but I think it's pretty safe to assume it's either NCA or NCM. The pack weight is from using cells with similar energy density as Tesla's -- perhaps slightly less, even -- and designing a very light pack. The cooling is passive. See US patent: Patent US20140234686 - Thermal Interface and Thermal Management System for Battery Cells

 

[dpeilow]

So to be clear: The pack itself is air cooled via the ridges on the outside?

 

[Rashomon]

The pack is air-cooled, and because high-draw events (i.e., a 20 to 30 minute motocross heat) will be relatively short, the cooling and thermal mass of the pack will get them through the event. Motocross racing actually has a small percentage of time spent at WOT (wide-open-throttle), say 1 to 5 percent compared to 30 to 50 percent on a road race course, which makes their life easier -- but cooling is much less efficient at the lower speeds in motocross. In most trail riding, where Alta claims 2 hours of riding time, the current draws are even less, and cooling shouldn't be an issue.

 

[dpeilow]

For the application I'm thinking of I might need five of these in parallel (or pack of equivalent size) operating at 0.3 C for worst case 3 hours. Be interesting to see if that would be a problem.

 

[voyager]

Can we say that 1 kWh battery (sorry for the metrics) weighs around 6 kg?
Tesla Model S 90 kWH has a 540 kg battery on board.

Are there any new developments in improving this ratio? I can remember Bosch says it will be able to slice off 30 percent weight...

 

[dpeilow]

The 100 kWh pack is slightly more energy dense and the best I have ever seen is the air cooled pack from the Alta Motors motorcycle with 5.8 kWh in 30.8 kg.

However hopefully we are close to "Battery Day" and we may hear about some developments that eclipse this.

 

[voyager]

https://www.researchgate.net/post/How_do_I_determine_the_energy_density_wh_kg_of_the_Li_ion_battery

Electric car battery with 600 miles of range? This startup claims to have done it