I put an almost empty pack(CA indicated nothing in the battery charge indicator, but resting voltage was about 44V, demonstrating it maybe had 20-25% charge left) up to the Satiator charger today. It charged it to full in 2.5 hours, putting 7.4AH back into the pack, the pack being rated 46.8V 10.5AH. I got about 45 miles from those 7.4AH. So, the 8 wh/mi I've been getting over the past two days is consistent, and this is in cold weather where efficiency and deliverable capacity both tend to suffer.
That is not bad.
I also rode it for 4 miles with the battery disconnected and the motor giving me its cogging losses. I maintained a rolling average of 14.5 mph. Keep in mind I live in a hilly area. And I'm still operating without the tail, which the lack thereof adds a noticeable amount of drag. I peaked at 38 mph going down a moderate hill for that ride, and on anything resembling a flat section, was holding about 20 mph.
Once I get the tail on it, and work out a few issues with the torque sensor so that it more accurately reads human power(and would thus probably require me to put out a little more pedal force to maintain 30 mph), maybe I'll have an 80 mile range at 30 mph with everything turned on. That would be very good range for a 491 Wh pack.
I'm looking forward to what the future holds for this project. This is going to be an excellent test bed to figure out what I really want for the next build. I'm going to make a 3rd body shell for this KMX for sure, just to try to get the aero right. I want to be able to sprint to 40 mph on flat ground with the EV system shut off and while overcoming the motor's cogging losses. As it was with the tail, I could only reach 37 mph, without the heavy/lossy motor in the back slowing me down, and now with the motor installed but without the tail, my flat ground sprints top out around 32 mph when everything is disabled.
I'm about to go for another ride and find a good place with no possibility of law enforcement encounters and do a genuine top speed run with the motor on.
Some brainstorming/musing for what may be the next build:
I think my next build is going to have the same 39" track width, but the wheelbase will be extended out another foot or more, and it will use a rack and pinion steering system like a car(probably one sourced from a racing kart) where one-half turn of the steering wheel from center equates to a turn of minimum radius, which would allow me to keep the brake levers on the steering, and the "wheel" will be a butterfly style like found on a fighter jet. I'd make a custom frame designed to allow the seat to be lowered an extra 2" from what I have now, and it would be reclined a lot more, to keep the center of gravity as low as possible. Probably go with 16" motorcycle wheels all around with Mitas MC2 LRR tires, hydraulic disc brakes, full suspension with about 1.5-2" travel(really don't need anymore), and a ground clearance around 4-4.5". I'd have some wheel hubs custom made, strong enough to handle highway speeds with reliability, laced to some light-duty motorcycle rims. I'd work on making the body as slippery and low frontal area as possible in the context of the wide front track width, possibly frontal area in the 0.45-0.5 m^2 region. This one may end up shaped something like the Versatron Vector from the 1980s, but with less glass and more roof, and solar panels on that roof, perhaps as much as 200W worth of them could fit on the vehicle.
A Leafbike 1500W 3T wind would be a good start for the motor, and I'd get one of the high-end controllers(Nucular Electronics, BAC8000, ect) and run it at like 96V or more, so the top speed would be no less than 90 mph, maybe more if a higher voltage pack can be accommodated, since 100+ mph would be really nice. A 150A max phase current and 7 kW power limit should be good for 0-30 mph in 4 seconds, 0-60 mph in 10 seconds, assuming an unladen weight of 100 lbs and a 140 lb rider with 30 lbs tools/luggage/spare parts. It would need a torque sensing bottom bracket modified to accommodate a Schlumpf HS drive with a triple crank, and perhaps a 26/40/52T crank that the HS drive could multiply by 2.5x into a 65/100/130 when engaged, with a 7-speed 34-11 freewheel in the rear. This would give gearing for climbing a steep hill unpowered and loaded for touring at 2.6 mph at 60 cadence, in top gear cruising at 70 mph at 100 cadence, and careening down the highway at 100 mph at 140 cadence. Get it efficient enough, say a CdA of 0.06 m^2, and a fit rider might still sprint to 45 mph on flat ground with the motor turned completely off due to a drained battery and suffering the cogging losses from no power going to the motor at all, and be able to maintain 25 mph for hours on end.
I know this is possible. My current preliminary results are very encouraging. And speed/performance is only a question of when hub motors catch up to existing technology, as the Leafbike is a far cry from what is possible from even 5 years ago. A 7 lb synchronous reluctance hub motor could be made for 3 kW continuous and 15 kW peak at 96V due to its high efficiency, make cogging losses and rotational inertia almost completely unnoticable to a fit rider when ridden powered off, and such a thing would make musclecar-like acceleration in a vehicle like this possible, forget the slow ass 0-60 in 10 seconds proposal, maybe 0-60 mph in 4-5 seconds in such a vehicle can be done... What fun that would be! And once solid state batteries enter the market in the near to mid-term future, we're looking at the prospect of stuffing a 4 kWh pack in a 15 lb package, which could give such a thing a 200+ mile range at 60 mph with the rider inputting 150W and the motor doing the rest. The operator would literally get thousands of miles per gallon over the life of the vehicle, and it would be efficient enough for solar to be the sole source of power for most people given that a modest amount of solar could give it 100+ miles range a day in most of the world.
This is the type of "car" that can be sustainable if all 8 billion people on Earth were to have one. And it wouldn't have to suck.
