ishiwgao Great question, certainly no offense taken this is an open discussion where anything relevant goes.
I'm really into rock crawling. It's super fun. Very technical driving, thats slow paced so for the most part there is low risk of injury while still keeping the adrenaline up. I had a solid axle swapped 1989 Toyota 4runner, locked differentials with lower gears, chromoly axles and 39" tires. It is great fun to go for a camping/wheeling weekend where you basically drive on trails, drink beer eat food and talk shit all day and night.
Part of going off roading with decades old, beat up and neglected trucks is that they are pretty much always on the verge of breaking down for lots of reasons. I think an electric motor and batteries, after a few bugs are worked out, will be significantly more reliable than the old Toyota ICE and supporting systems. More time having fun, less time broken on the few weekends a year we get together.
Rock crawling specifically is also well suited to electric drive, where low end torque is desired over sustained high output. You can have fun all day in a rock crawler and never go farther than a 5 mile radius from camp or go over 20 mph.
So I've been talking/dreaming about it for years, and finally overheated my motor earlier this year and its not worth repair. Lots of thought/research, including guidance from this site, plus budget constraints led me to the Leaf components. A running driving Leaf could be had in the ~$3500 range, which would yield a motor and batteries. Thunderstuck has the Leaf VCU for $500, and I knew there would be more components to buy but I figured this was the most economical way to get my 'runner de-ICEd with a modern, powerful AC motor(regen) with Li-ion batteries. I knew the capacity wouldn't be great, but I decided it was a compromise I was willing to take for now. The idea being get the thing running and driving, and in time upgrade the batteries. So I bought a donor September '20, a 50k 2015 Leaf salvage title running and driving for $4000 and started collecting parts.
Then I got a call that there would be a new EV only class at the February 2021 King of the Hammers event. KOH is the largest rock crawling event in the world, over 50,000 attend annually for a week of racing in the So Cal desert.
Element of Survival is a really cool video to watch to get an idea of the cars and terrain, lots of other videos documenting the race can be found easily.
That's when the plan changed, I knew I had to compete. A team was made of coworkers, friends and family. We don't have time to turn my beat up Toyota into a racecar due to what's required for safety. A friend who had an old 4600 class 4runner racecar that has previously competed in KOH offered his chassis to convert. So I sold my crawler and am all in on converting this car.
The challenge is a ~90 mile loop, with 2 pit stops. There will be about a 20 mile section, pitstop, 45 mile section, pitstop, and a third ~20 mile section. It will include steep sandy hills, rock crawling, and long straight flats. The 24kwh pack that came in the car will not be anywhere close to accomplishing this. We decided swapping discharged batteries for charged ones at pit is how we will tackle the problem. Based on napkin math, two fully charged 24kwh packs cannot be relied upon to take the vehicle 45 miles. So we need to used the later model higher capacity packs. Sticking with Leaf modules because I've already invested in the Dilithium 96 cell BMS and am somewhat comfortable with them. I like the simplicity of the aircooled design, even though it compromises performance.
The late model packs are hard to find. I found a salvage yard that has a 40 and a 62, and they are charging the same price. I know the 40 will bolt into what we built, but I couldn't bring myself to pay the same price for ~50% less capacity. I am also actively searching for two more packs, ideally 1 40kwh and 1 24kwh. That would give us lots of battery options, and those packs would have basically no more unknowns when it comes to packaging/wiring. Also, after the race, the loose plan is to get myself another rock crawler chassis, another Leaf motor, and split the batteries between the two vehicles, on an agreement that owner of this car will purchase the batteries/electronics that stay in his car.
That pretty much brings this story up to date. It has defiantly been an evolution. Ideally there would have been a clear goal, component list and execution plan from the outset, but that's not how this one is working out. Have learned alot so far, looking forward to the real-world data of EV energy consumption in a 4x4 vehicle that weighs 5000lbs+ with 35 inch offroad tires traveling some of the gnarliest terrain in the world.
62kwh pack ships today from Tennessee to California, cant wait to get it here and tear it down.
Pictures of Hammertown and race action on the trail Backdoor, roughly 2015 perhaps earlier.