Saturday, January 31, 2009

Pumpkin Interference, IV

It's full steam ahead on the "rotate the motor 180 degrees" project to overcome the pumpkin interference. I removed the motor and installed the new mounting points and bushings:

It was not strictly necessary, but the old ones were in questionable shape, and these are heavier-duty (designed to support the 4.0 liter engine). I also rotated the profile plate 180 degrees - note that the motor "feet" are now on top:

And I cleaned up and cut all the metal pieces for the motor mounts:

I spent some time drilling holes, but there are quite a few more holes to drill and welding to do. Cooler weather is rolling in; hard to tell how much I'll get done tomorrow...

Friday, January 30, 2009

Pumpkin Interference, III

I spent most of my spare hours this week wracking my brain for a solution for the motor mounting problem. I finally bit the bullet and drew a very accurate SketchUp model of the AC55 motor, plus a drawing of the new motor mounts & bushings. I also carefully measured the distances between the motor mounts, as well as the angle of the motor (5 degrees). Using all this information, I figured out a motor mounting scheme that, although a little baroque, I think will work very well:

Here is just the left side, from behind. The new mount has mirror-image left and right sides. Each side is composed of two parts which swivel about a large 1/2" bolt. Below, you can see the two parts - one of them is bolted to the motor mounting point, and the other gets bolted to the motor. This pivot allows some adjustment to be made to the motor angle (I'll probably also enlarge the hole that the pivot bolt goes through to allow for some adjustment). The two halves will be welded together, but there are 1/2" bolts on the part that attaches to the motor to give it more tensile strength:

Here are a few exploded views of all the parts. Once I get this built accurately, I'll take final measurements and update with a PDF drawing of the assembly:

Tomorrow promises to be warm-ish (55 degrees) and sunny - perfect welding weather... hopefully I can get this completed in one day.

Tuesday, January 27, 2009

Pumpkin Interference, II

After some thought, I've decided on a combination of approaches to solve the motor / differential interference. First, I bought some aluminum 1.5" lift spaces and installed them this weekend (side note: I'm tired of wrestling these springs. This is the *last* time I remove / reinstall them...):

This shows the clearance gained by doing this:

That's without batteries installed, of course - with 500 pounds of lead in front, and with a new adjustable trackbar installed, I expect that clearance to shrink to about 1.5 inches (which, no surprise, is the height of the new spacer).

Next, I'll gain another inch by either rotating the motor 180 degrees or by moving the motor mounting points back (stay tuned...)

It's been really *cold* this week, so that is likely all until this weekend.

Saturday, January 17, 2009

Pumpkin Interference

No, not the gourd - the differential case is sometimes known as the "pumpkin". As I was preparing to put the ElectroJeep back in the garage for the miscellaneous final things that need to be done, I took a look at the front differential - I expected the springs / shocks would have settled some after going over the curbs, etc. And I was right. The motor mount was resting on the front differential. This is very bad - going over a bump with any significant force would cause serious damage. In fact, even the 100 gentle feet I drove caused damage to the mount - see the lower left corner - bent and scarred (this picture was taken with the Jeep jacked up, so the front axle is dangling):

So, the whole thing needs to move up. I have about an inch of clearance on top:

I also need to move the crossmember toward the rear of the Jeep. This causes, umm, interesting challenges if I am to use the original motor mounting points. Here is one design, showing a heavy 1" box tubing framework that pushes the hanging point toward the face of the motor (it would all ride on a 1/2" threaded rod, shown, that runs the whole length of the assembly):

I would also have to remove most of the aluminum foot on the driver's side of the motor (highlighted in blue here). This would give me nearly two inches of clearance - and I could put a rubber "bump stop" or something down there in case of an extreme bump.

The other option, not shown, would be to rotate the motor 180 degrees so the "foot" is on top, and the motor is hanging from a support stretched across / between the two motor mounting points. But the size of the foot means that there would not be as much clearance between the differential and the motor. And I think I need all the clearance I can get...

Friday, January 9, 2009

More Motor Notes

I stumbled across some data on the Jeep's original engine and its performance. The original gas engine was an "AMC 250 I4" - a 2.5L 4-cylinder engine. This curve shows its torque versus the various electric motors I have data on:

Here is its horsepower - immense at high RPM. However, nobody runs the engine at race-car speeds of 5000+ RPM. When we drove it around before, we typically kept it under around 3000 RPM because nobody liked riding in the Jeep with the engine / tranny screaming like a banshee:

Using the data on the gearing ratios of the AX-5 transmission and Dana 35 rear axle, here are the various shifting ranges. The solid lines are the AC55; the dashed lines are the original AMC 250 I4. I assumed that both gas and electric would not be run at more than about 3000 RPM to make this chart.

Again, this highlights why you want a transmission. Although you *could* just run around in 4th gear all the time, you'd be really slow off the line as you started. And running electric motors at low RPM is fairly inefficient.

It will be interesting to see if that comparatively low performance above 60 MPH will limit the vehicle usability in any way. I suspect not - it is an in-town vehicle. Even at 75 MPH it's only missing about 15% performance relative to the gas motor.

For future reference - I believe the gearing ratios of my Jeep are:

  • First gear: 3.93
  • Second gear: 2.33
  • Third gear: 1.45
  • Fourth gear: 1.00
  • Fifth gear: 0.85
The Dana 35 final axle ratio is 4.10, and I'm assuming I'm running 31-inch tires.

Thursday, January 8, 2009

It's alive! Really alive!

YouTube link.

After some email back-and-forth with Azure Dynamics, they figured out that I had incorrectly labeled my 3-phase motor cables. I had swapped "A" and "B". To keep the lengths properly aligned ("C" must be 1.5 inches longer than "B", and "B" must be 1.5 inches longer than "A") and to avoid further shortening my motor cable, I made up three patch cables of the proper lengths. The labels on these patch cables are "AM" for "A, motor side", "AC" for "A, controller side", "BM" for "B, motor side", and so forth:

I unbolted the motor cable, and bolted the extensions on with stainless steel hardware:

I heat-shrink wrapped all three:

I still had the shielding braid from the really long cable, so I cut a piece to an appropriate length to splice between the DMOC and the original shield:

I zip-tied the new shield over the old shield, providing a continuous ground contact, bolted the three cables in, and tightened the fitting:

And it works! I drove the Jeep out and around, and parked it back in our gravel drive:

And here it is, charging next to the Volt914:

Sadly, during all this, the Manzanita Micro charger has developed a fault - it blows the breakers in the house panels when it is turned on. So, I get to send it back for diagnosis and repair. But I can charge the batteries individually for now...

Thursday, January 1, 2009

Electric New Year, Jeep Style

Just like on the volt914, I mounted an "ELECTRIC" label on the back of the Jeep. Happy New Year - and good luck to all those conversion fanatics out there!

Potbox / Throttle

Today, I mounted the potbox and attached the throttle pedal to it. I started with some 2" by 1/8" aluminum bar stock and made some bends:

And more bends... (sadly, I made this bend backwards):

Here's the final bent-up mount. Because that bend above is the wrong direction, I had to add one more bend to turn the forward extension around 180 degrees. You can see the four holes on that extension where the potbox will be mounted:

Here's the potbox mounted in its new home:

And here's the whole thing in its final location. The springs in the potbox push the lever toward the front of the Jeep. The threaded rod pushes on the throttle pedal. Because of the lever point, this means the footrest on the pedal moves *backwards* and resists foot pressure:

It works fairly well. I may upgrade the 10-24 threaded rod to 1/4-20 - the 10-24 was fine when I was thinking of using the throttle to *pull* the arm back, but *pushing* causes the thin rod to bend a bit, adding some undesirable "springiness" to the assembly.