Electric car conversion: Project ForkenSwift

[MetroMPG]

Why check the motor rotation?

It occurred to me that we never checked that it was a clockwise motor. My understanding is most transmissions (input shafts) run clockwise (Honda being one exception), and some e-motors only run in one direction due to brush timing. Just verifying that we didn't have one of those motors and weren't stuck with a mismatch. (Kind of thought of that late in the process, but oh well. It all turned out OK.)

[MetroMPG]

This week Ivan made up the motor mount bracket and the bracket to secure the right axle "hanger bearing". We installed them last night. Will post some pics later.

So!

The motor is now bolted into position, with the Lovejoy coupler attached to the transmission. We just need to tighten up a bunch of bolts on the adapter plate and drivetrain mounts.

I'm going to try figuring out my golf cart controller later today ... in preparation for the SPINNING OF THE WHEELS ceremony sometime this week - on jack stands. To be followed, possibly , by our first electric test drive.

[MetroMPG]

Some pics... Clicky-zoomy...



Above: Ivan's work - adapted the original 2 "belly straps" that held the 2 motors in place under the forklift (shown at top, from under the beast) into an elegant 2-part motor mount bracket.



Motor's in the car! The e-motor shown installed on the car's original ICE mount hardware. The dimensions of the motor (length & width) are remarkably close to the ICE. Makes this stuff somewhat easier.



Above: shot from the back side of the motor, looking down and forward (firewall is bottom left, right shock tower @ bottom right) ... the hanger bearing (center) that stabilizes the longer right axle used to be bolted to the back of the ICE block. Ivan made up a couple of plates to connect it to the unused side of the tranny/ICE mount bracket.



Last thing we did was cut an inspection window in the top of the tranny bell housing so we can keep an eye on our coupler. This is the part of the works we think is most likely to wear out and/or break. Crappy pic due to glare off the adapter plate. But that's the Lovejoy in there...

[MetroMPG]

Well, here's a bit of a blunder:

Contrary to what I reported a few posts back, our motor does NOT reverse direction by reversing the polarity on its 2 terminals. And guess what: its default rotation is the WRONG way for the transmission.

Permanent magnet motors can run either direction depending on polarity of the armature. 4-terminal series motors can be run either way by reversing the polarity of the field. (Assuming neutral brush timing and perpendicular brush/commutator setup.)

But I learned last night that 2-terminal series motors (such as we have) are wired to only rotate in one direction, regardless of polarity at the terminals.

So now we have to look at rewiring the field.

I won't pretend otherwise: this could be a grande screwup. When we hooked up the motor on the bench last week and reversed the polarity, we only confirmed that the motor ran. We didn't think to actually look in the end and check that the shaft was spinning the opposite way.

Worst case scenario: we have 2 pump motors that would work great on Honda transmissions!

More likely we just have to reverse (re-route) connections between the field & brushes/rotor.

I'm sure my ignorance must be entertaining. Still on ye olde learning curve, that's for sure.

[MetroMPG]

SW appreciates my being candid:

First, thanks for sharing your experiennce, especially the small blunders. It's important to see where the difficult areas are. I found few things as infuriating as the many procedural manuals (computer and automotive alike) that said something like "simply remove the bearing and the shaft will come right out..." when it really took hours of hard struggling because I missed an important but undocumented step.

Good news that you have a 'sister' motor on which you can make your wiring experiments before "simply removing" the main motor.

Does this mean you need to retest the brush timing in the proper direction?

[MetroMPG]

Yes, that was certainly an important but undocumented missed step!

Some good news: Ivan opened up the sister motor and it looks like the wiring to the field is pretty straightforward. He disconnected both ends of the field circuit, jury rigged a patch in place to reverse them and got it to run "backwards". Also, the brushes appear to be set vertically, so they shouldn't pose a problem running opposite to the original direction of the commutator. (I'd read that some brushes are set on an angle, and that would pose a problem for reversing rotation.)

FYI for anyone interested in this, here's a link from the EV archive about 4- vs 2-terminal series motors that tipped me off to the potential roblem we were facing.

So we just have to make up a pair of "jumper" wires of the proper gauge to mod the motor to run in the direction we need it to.

Also fortunately, removing the e-motor from the car is not a huge job: maybe 10 minutes for 2 people. Much easier than the ICE removal

[MetroMPG]

Re: retesting the brush timing...

Not sure about this part. Need to do some more reading and looking at the motors.

[MetroMPG]

So, apparently the easy way to tell if a motor has neutral brush timing is to simply run it in both directions. If it runs faster in one direction, the brushes are advanced against that direction. Good thing we have 2 motors. Makes a comparison relatively easy.

[MetroMPG]

Originally Posted by SW

Hook 'em together and see which one wins.

Hoo ha! That's a good one

FYI - what happens if you run a motor backwards when the brushes are advanced against rotation in the "default" direction:

I installed my brand new 8" motor as it was shipped to me, and in the first 5 miles it burned the brushes and ruined the commutator. Turn out that unlike other cars on Hondas the motor shaft rotates CW, but default plate advance is made for CCW. No one mentioned that, and I always thought that DC motors are symmetric. Expensive mistake, exactly because of brush advancing. I'm sure I am not the only one discovered it hard way.
Source: ev archive

Most motors run CCW (facing the output shaft) by default (ie turning the tranny input shaft CW). But this guy put his motor on one of them "backwards" Honda trannys (CCW input shaft), and just reversed his field to make the motor spin the other way. Oops. His brushes were timed for the other direction. Must have been some good fireworks going on that of course he couldn't see.

I guess I'll be looking pretty carefully at this this weekend.

[MetroMPG]

Pulled the motor out again this evening - a 5 minute job. How cool is that?

Started working on the field polarity switch. Not a 5 minute job.

It's a conceptually simple task, but had to run around borrowing tools - first a honking soldering iron which wouldn't do it, then a torch set - to de-solder two connections, blah blah blah. It took a long time, and we didn't get it finished. But should be done tomorrow.

Then we reassemble and test the "new" CCW motor RPM against "stock" CW RPM of sister motor - to determine if the brushes are neutral or not. Hoping they are (it'll save time). Should have compared RPM of both motors in stock form before all this, but I wasn't being very scientific.