60kWh software limited battery swap?

[cashcow]

[moderator edit - "kw" is changed to "kWh"]

Seeing the RAV4 EV runs a 40 something ish kWh battery pack it made me wonder if the 60kWh software limited battery packs some "40kWh" Tesla Model S EVs are running could be the same size / compatible with the rav4 ev battery pack size/bolts/space? I don't know if it is the same size or well more specifically same form factor but it made me wonder. I would guess the wiring harness would have to be upgraded? Unless the cables are thick enough? The bigger problems... I would guess... would be the software side of the upgrade?

 

[TonyWilliams]

I seriously doubt it would fit, but somebody could do a little measuring. It is probably smarter to just change the cells inside the battery box. Even if it bolted in, the voltage isn't exactly right.

The 2012-2014 Toyota RAV4 EV uses a Tesla built battery pack, with Panasonic 18650 cells rated at 2600mAh.

There are 4416 cells at 4.2 volts per cell maximum. That is 386 volts maximum pack voltage.

92 in series * 48 in parallel = 4416 cells total

4416 cells * (2.6Ah * 3.7v nominal) = 42.5kWh

************************************************

The Tesla Model S with 60kWh (first generation) is also Panasonic 18650 cells, however the cells are 3100mAh.

5040 cells total, 84 in series * 4.2 volts per cell max = 354 volts max pack voltage.

84 in series * 60 in parallel = 5040 cells

5040 cells * (3.1Ah * 3.7v nominal) = 57.8kWh

***********************************************

Telsa Model S with 60kWh pack (second generation), limited from a 75kWh total capacity also uses 18650 cells @ 3100mAh.

6216 cells total, 84 in series * 4.2 volts per cell max = 354 volts max pack voltage.

84 in series * 74 in parallel = 6216 cells.

6216 cells * (3.1Ah * 3.7v nominal) = 71.3kWh

 

[EnerGene]

Tony, do you have some good high res photo's of the RAV4 pack opened up?

 

[TonyWilliams]

Tony, do you have some good high res photo's of the RAV4 pack opened up?

Sorry, I don't... someday. It won't look significantly different than all the pics on the web of the Model S battery. Just Google "tesla battery inside" and you'll get all kinds of pics:

http://insideevs.com/look-inside-a-tesla-model-s-battery-pac/

 

[cashcow]

Great idea Tony on replacement of individual batteries inside the pack instead of doing a full pack transplant. Would you recommend this for bringing the current pack to 'new' stats (No degradation) or instead swapping the batteries for the newer ones (Talking about the new 21700s batteries).

Also if we use the newer batteries will we still aim for the 386 Volts maximum pack Voltage?

Is the voltage aim mainly because of the software the rav4 ev uses to manage the charging?

 

[Larry_in_Seattle]

It sure would be sweet to be able to do a drop in 71 kW replacement battery pack for our 41.8kWh ones! Almost double the range, JdeMO and a cold beer right now as I fantasize about it.... YEAH. (At least I got a cold beer out of this!)

 

[TonyWilliams]

I seriously doubt that the 2170 cells would be a fun swap.

I suspect it is smarter / easier / cheaper to continue use of the 18650 cells.

If the existing 2600ma cells were swapped with 3400ma, you would have a pack that has about 30% more capacity.

92 cells in series x 48 parallel = 4416 cells

382 volts @ 4.15v (resting OCV max)
386 volts @ 4.2v (charging / regen max)

 

[miimura]

The numbers just hit me. Doing a production run of new modules for battery packs for just 5% of the RAV4 EVs ever made (130 cars) would require 574,080 battery cells. Damn. I just did the math because I was thinking about what would be required to make new modules to put in the RAV's battery pack shell. It's a lot of fixtures and you would need a special wire bonding machine, at a minimum.

 

[TonyWilliams]

Yes, not insignificant costs and effort.