OK, my mass numbers might be off. I'll take another look at it.
Car and Driver reviewd a 2014 BMW i3 years ago when it was all new, smaller battery, etc., and said:
"BMW calls its skateboard the Drive Module, and fashions it almost entirely from aluminum. The framework surrounding the 450-pound lithium-ion battery pack
, the front control arms, and even the bolts that attach the chassis to the body are all aluminum. Only the rear suspension links are steel. Atop the Drive module sits the Life module, which is crafted primarily from carbon fiber. The body structure and roof panel are made from that stuff, while the body panels are composite. Throw in some other lightweight materials, such as a magnesium dash brace and hemp-reinforced interior plastics (maybe that’s why the drive program was conducted in Amsterdam), and the whole thing (with range-extender) weighs about 2900 pounds
. That’s roughly 450 less than a Nissan Leaf and in the same mass neighborhood as a Chevy Spark, an entirely conventional car that is a bit smaller than the i3. Remember that business about BMW core values? Naturally, those 2900 pounds are evenly distributed between the front and rear axles." -- https://www.caranddriver.com/reviews/a1 ... ve-review/
I think the 450 lb battery pack weight they mention (22 kWH battery from 2014) includes all the metal hardware surrounding the battery, not just the cell weight, BTW, it's the whole unit battery pack. ...... For comparison, the 21 kWH LG Chem pack in the Ford Focus Electric of that same era was 640 lbs, so 450 lbs sounds like they could be leaving something out. Not sure. Or it just beat the old LG Chem pack by 200 lbs(?).
When the IIHS crushed the roof of a 2019
BMW i3 (not ReX), they actually weighed it on their own scales at 2,920 lbs, & since they do that in the U.S., I assume that was without a driver, IOTW, a U.S. style "curb weight".
Similar to a 2019, a 2020 BMW i3 (not Rex) is listed by Car and Driver as "2,972 lbs", and they now say a 2014 i3 (not ReX) is 2,860 lbs.
So going from 2014 to 2020, the higher 120 Ah battery packs do add mass, as expected.
Here, from the Deep Blue BMW i3 120 ah battery Torqeedo will sell you, straight from the BMW-Dingolfing factory, is:
.... which is the complete stressed-member Battery Box weighing 613 lbs. Compare to a Bolt's battery box at 960 lbs (or 947 lbs for their latest version according to GM), also a stressed box package. We could also add in a little extra BMW i3 structure to handle our imaginary battery swap for the bigger Bolt battery, probably around 30 lbs extra structure needed for bracing.
From what I can see, getting info from multiple sources, the numbers I used originally are right.