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The issue with an EREV conversion is going to be weight, practicality, and thermal management of the battery. Weight: You're adding about 500 lbs to the car to

The issue with an EREV conversion is going to be weight, practicality, and thermal management of the battery. Weight: You're adding about 500 lbs to the car to do this with ~20 miles of ev range. Suspension may need to be altered to support this. Practicality: the batteries have to go somewhere and they can't go under the hood since the engine is still there, so they may go in the bottom of the trunk. From the examples I've seen there's usually less cargo capacity, and the spare tire is removed. Some vehicles that are already hybrids (e.g. Toyota sienna 2022-) have an already tight layout with exhaust and all that it becomes a design challenge to fit a larger battery. Thermals: a li-ion battery for an EREV likely needs thermal management so it doesn't lose range prematurely, so you either need a dedicated cooling line setup that works with the ac compressor (bmw i3) or an aircooled setup where the battery is in the trunk and relies on cabin ac/heat (various toyota hybrid models do this).

hwillis 2y ago
> Weight: You're adding about 500 lbs to the car to do this with ~20 miles of ev range. No. The drive unit of a Tesla + 4 battery modules weighs 500 lbs. That's 21 kWh, 80 miles of range and 500 horsepower. And 300 lbs of that is in the drive unit; more common conversion kits weigh ~150 lbs. You could use 500 lbs of regular lead car batteries and still get way more than 20 miles. https://stealthev.com/product/tesla-performance-rear-drive-unit/ https://stealthev.com/product/tesla-performance-rear-drive-u... https://www.evwest.com/catalog/product_info.php?cPath=40&products_id=583 https://www.evwest.com/catalog/product_info.php?cPath=40&pro...
- horsawlarway 2y ago
  I'm not sure I agree. You would need 24 LFP prismatic EVE cells (Which are EV rated) to get to ~20kWh (72v at ~300ah). They weigh about 5.5kg/cell. That's nearly 300lbs in cells alone (not accounting for wiring/support/cooling). I would pretty easily see total weight hitting 500lbs (or more). You can do it more efficiently with different chemistries, and you can scale down your storage for less range - but 500lbs seems pretty reasonable for a retrofit. Ex - your own linked kit doesn't include any storage, and the motor alone weighs 120lbs. There is NO WAY you're getting away with 150 lbs when the motor alone eats 120lbs. Lead acid... come on... a 100ah 12v lead acid (1.2kWh - of which only .6kWh is really usable because of chemistry) weighs 70lbs on a good day. A normal EV will do 3-4/kwh. 5kWh of usable charge (20 mile range) from those things is going to run you 10 batteries, for 660lbs. And that's NOT including any other parts of the retrofit (like that 120lb motor, or the wiring [thick wire is heavy] or the electronics).
  - hwillis 2y ago
    https://stealthev.com/product/tesla-module/ https://stealthev.com/product/tesla-module/
    - horsawlarway 2y ago
      To be clear - this is 55lbs for 5kwh of power in a 22v nominal pack. You will need more than one to get to 20 miles of range in an aftermarket conversion, and you will still have to add 100+lbs of motor on top, in addition to cooling/wiring/electronics. I see this system coming in around 300lbs on the low side. Again - the battery is not the system, and this is still 100lbs of battery to get to 20m of range in an aftermarket conversion.
- seltzered_ 2y ago
  My points of comparison are simpler - compare a 2019-2023 Subaru Crosstrek (regular non-hybrid model, curb weight of 3117-3298 lbs ) to a 2019-2023 Subaru Crosstrek Hybrid (PHEV, ~17 miles of EV range, curb weight of 3717 lbs). So roughly a 400-500lb weight increase. Another comparison might be a Jeep Wrangler base 4dr (4449 lbs curb weight and up) compared to the 4xe PHEV version (21 miles of ev range, 5,072 lbs curb weight and up). Roughly a 500lb weight increase. You could try this comparison on 2wd vehicles as well if desired (e.g. toyota prius vs. prius prime). While neither scenarios are an EREV, the comparison is a bit similar in thinking about the tradeoffs in hybrid conversions of existing ICE vehicles, where presumably the engine would be retained and drivetrain/battery components to facilitate electric propulsion are added. Designing an EREV from ground up can be much less weight but depends on vehicle type size, such as a BMW I3 (a small urban 2WD car with CFRP body panels, narrower staggered wheels and other weight savings by design) has a curb weight closer to 3276 lbs. There's tradeoffs with that low weight - the small range extender engine has less power, the gas tank only adds about 80 miles of range, etc.

hwillis 2y ago

> Weight: You're adding about 500 lbs to the car to do this with ~20 miles of ev range. No. The drive unit of a Tesla + 4 battery modules weighs 500 lbs. That's 21 kWh, 80 miles of range and 500 horsepower. And 300 lbs of that is in the drive unit; more common conversion kits weigh ~150 lbs. You could use 500 lbs of regular lead car batteries and still get way more than 20 miles. https://stealthev.com/product/tesla-performance-rear-drive-unit/ https://stealthev.com/product/tesla-performance-rear-drive-u... https://www.evwest.com/catalog/product_info.php?cPath=40&products_id=583 https://www.evwest.com/catalog/product_info.php?cPath=40&pro...

horsawlarway 2y ago
I'm not sure I agree. You would need 24 LFP prismatic EVE cells (Which are EV rated) to get to ~20kWh (72v at ~300ah). They weigh about 5.5kg/cell. That's nearly 300lbs in cells alone (not accounting for wiring/support/cooling). I would pretty easily see total weight hitting 500lbs (or more). You can do it more efficiently with different chemistries, and you can scale down your storage for less range - but 500lbs seems pretty reasonable for a retrofit. Ex - your own linked kit doesn't include any storage, and the motor alone weighs 120lbs. There is NO WAY you're getting away with 150 lbs when the motor alone eats 120lbs. Lead acid... come on... a 100ah 12v lead acid (1.2kWh - of which only .6kWh is really usable because of chemistry) weighs 70lbs on a good day. A normal EV will do 3-4/kwh. 5kWh of usable charge (20 mile range) from those things is going to run you 10 batteries, for 660lbs. And that's NOT including any other parts of the retrofit (like that 120lb motor, or the wiring [thick wire is heavy] or the electronics).
- hwillis 2y ago
  https://stealthev.com/product/tesla-module/ https://stealthev.com/product/tesla-module/
  - horsawlarway 2y ago
    To be clear - this is 55lbs for 5kwh of power in a 22v nominal pack. You will need more than one to get to 20 miles of range in an aftermarket conversion, and you will still have to add 100+lbs of motor on top, in addition to cooling/wiring/electronics. I see this system coming in around 300lbs on the low side. Again - the battery is not the system, and this is still 100lbs of battery to get to 20m of range in an aftermarket conversion.
seltzered_ 2y ago
My points of comparison are simpler - compare a 2019-2023 Subaru Crosstrek (regular non-hybrid model, curb weight of 3117-3298 lbs ) to a 2019-2023 Subaru Crosstrek Hybrid (PHEV, ~17 miles of EV range, curb weight of 3717 lbs). So roughly a 400-500lb weight increase. Another comparison might be a Jeep Wrangler base 4dr (4449 lbs curb weight and up) compared to the 4xe PHEV version (21 miles of ev range, 5,072 lbs curb weight and up). Roughly a 500lb weight increase. You could try this comparison on 2wd vehicles as well if desired (e.g. toyota prius vs. prius prime). While neither scenarios are an EREV, the comparison is a bit similar in thinking about the tradeoffs in hybrid conversions of existing ICE vehicles, where presumably the engine would be retained and drivetrain/battery components to facilitate electric propulsion are added. Designing an EREV from ground up can be much less weight but depends on vehicle type size, such as a BMW I3 (a small urban 2WD car with CFRP body panels, narrower staggered wheels and other weight savings by design) has a curb weight closer to 3276 lbs. There's tradeoffs with that low weight - the small range extender engine has less power, the gas tank only adds about 80 miles of range, etc.