Right, you need to do that engineering yourself. And ICE engines are heavy, so it typically is reasonable to work out as the lighter engine compensates for the battery weight. It is a design task, not a project killer.
If modern EVs are anything to go by, the battery weight will be substantially more than the weight of an ICE engine plus gearbox etc. But yes, it'd be for the hobbyist to figure out the details and whether it is safe enough to drive.
The EV version of the Hyundai Ioniq is only about 60 kg heavier than the hybrid version and at about 1 500 kg is not much over the average for cars of its class.
EVs really are not a great deal heavier than the ICE versions of the same or similar vehicles.
The Jaguar I-Pace EV is lighter than some variants of the F-Pace ICE.
Hyundai offers an EV version of the Casper: it's 1335kg vs 985kg for the petrol variant. Surely that's a great deal heavier? The Aygo finds an all-electric competitor in the Renault Zoë whose battery pack alone weighs 300kg, a hefty increase compared to the 70kg engine of the aygo. Volkswagen's up! comes in at 929kg; the e-up! registers at 1229kg.
Regarding the I-pace vs the F-pace I was unable to find more than a single version with a greater weight than the I-pace, though I admit I haven't analyzed the specs of all 108 editions. That single example weighing more was, of course, a hybrid.
EV versions are, primarily due to the weight of their battery packs, significantly heavier than their ICE counterparts and that's fine.
I'm not sure modern EVs are anything to go by. They are trying to meet the needs of a broad audience whereas you know exactly what you need out of a vehicle. For example, if you only need a 50 mile range, not 250, that is 80% of the weight down. No major manufacturer would put that out, but most drivers do less than 50 miles a day.
There are all kinds of design choices that can be made to fit completely within the original specs of the chassis.
I’m honestly amazed there are not more conversion kits. Pull the IC powertrain and gas tank, replace with battery and electric motor. It’s obviously way harder than it seems or I think a lot of folks would be doing it.
I think the main issue is that it takes a lot of engineering from the ground up to make an electric car with good range and performance. Maybe if batteries get significantly better, then conversions will get more popular.
They actually even make cars exactly like that. They’re pretty compromised cars though. An E-Golf for instance is just what it sounds like: they took the existing Golf and made it an EV.
