开云体育

Yes, absolutely you can raise the front wheels IF you supply enough amps.? When I did mine about 10 years ago, I cut my front shroud and made it into a hood.? I put the extra PbA batteries up front.? I used an Altrax 72450 450 amp controller.? This is unsatisfactory compared to the contract controller.? with the contact controller, flooring the pedal from a barely rolling start (to prevent burning a commutator bar), the current to the motor hard-pegged my 1000 amp tong tester.? The electronic controller by itself will supply a fraction of the torque supplied by the contact controller.? In a series motor, torque is generally treated proportional to the amps^2.

What I did was prepare the motor on my Terril axle motor for the added current



The ultimate current limit is that which makes the trailing arcs from the brushes reach the adjacent brush and flash over.? This can be eliminated by fitting the motor with arc scrapers.? These are small pieces of mica (min 2, preferably 3) mounted at an angle opposed to the rotation of the armature.? They almost touch the armature.? The rotating air near the commutator directs the arc off and away from the commutator,? What arc escapes the first scraper is caught by the second one.

Now the limit is the brush lead.? I took my brushes to my friend's (who unfortunately died a couple of months ago) electric motor shop.? I drilled a second hole in the rear of the brush and cemented a second lead into the hole with a copper dust/mercury amalgam.? I also had the stator dipped in Class H epoxy varnished and baked to cure it.? This greatly slows the rate of heating at high current AND it gives the field coils the strength not to blow off the poles at >1000 amps.

Since 450 amps is rather puny, I designed a controller bypass contactor system.? This contactor takes the controller out of the circuit and connects the battery directly to the motor a la the contact controller.? I designed an electronic board that is essentially a comparator.? A microswitch detects WOT.? One can't slam 72 volts onto the motor when the car is stationary.? Almost guaranteed to lift commutator bar(s) and probably break gears in the axle.? The board monitors the voltage across the motor.? I had mine set to 20 volts which is <5mph.? When the voltage is reached, the board closes the bypass controller.

When that happens, my car, even with the heavy PbA batteries up front, the steering got extremely light.? I'm not sure if the wheels actually left the ground but if not, they had practically no weight on them.? I clocked the car with my radar gun at 55mph. That's not the ultimate speed.? That's the speed when I ran out of guts!? The front wheels have almost no caster and essentially no toe to reduce rolling drag.? I built a jig so I could twist the axle such that it had 2 deg of caster and added 1/2" of toe-in. This nominally reduces the range but with a 72 volt pack, you and your butt will wear out before the pack does.

One other consideration if you go to this level of torque is the possibility of breaking the axle gears.? I had a spare axle or I would not have gone this far.

Before the steering geometry changes, at 50 mph, the car was almost uncontrollable.? worse, a bump (as in rolling over a large gravel) would cause it to hobby-horse.? I'm a former racer and am essentially feerless in a vehicle.? This had me white-knuclked!

When I had to sell my car because of health problems, I was working on fitting a sub-compact front axle to the car.? I had picked out the doner car but for the life of me I can't recall what model.? I also planned to lengthening the frame for more stability.? The previous owner had sheathed the car with aluminum panels (a very good job) so extending the panels would be simple.

To address another problem that was raised last week, namely the front brakes locking up and not releasing until the car came to a stop, here's the problem and solution.




Be SURE to read the update.? That is where the problem is described and fixed.



I don't recall what the Leaf battery amp rating is but I'm fairly sure you'll have to parallel two packs to supply the amperage.? I suggest a contactor that separates the packs for charging so that each pack has its own BMS.

PS:
A note about Tong Testers.? Everything I could find with a quick look on Google about this device is wrong.? As usual, Wikipedia is completely wrong.

The Tong Tester is a totally mechanical moving vane type of ammeter.? It measures AC, DC or AC riding on DC with equal accuracy.? It indicates true RMS.? It typically comes in a kit with the tong that clamps around the conductor and 4 range cartridges.? A cartridge is inserted into the tong and the magnetic field from the tong acts on an iron vane connected to the pointer.? It is the most accurate and repeatable ammeter I own.

Unfortunately it's been out of manufacture for a long time. They occasionally show up on sleazebay.? Two things to make sure of.? 1) the kit consists of the tong and 4 range cartridges. I've seen them for sale with only one or two cartridges. Second, the tong and the cartridges have small numbered stickers on them.? All numbers must be alike.? The cartridges have been individually calibrated to that individual tong.

I'll dig up some photos when I return from the (arggghh) dentist.

This device is so good that when I was doing my work-scholarship in a TVA nuclear plant, TVA would pay me to go to hamfests to buy up as many as I could.

John