Electric car conversion: Project ForkenSwift

[MetroMPG]

Hmm: http://www.fsipcatalog.com/p-4053-mo...ntiometer.aspx

0-5k ohm, says an email from the vendor. Diagram shows 3-wires. It's a slide pot, but that doesn't really matter. Looks like it may also have microswitches built in.

$14 plus shipping.

[MetroMPG]

Well, I got some advice & encouragement from an experienced EVer...

#1 salient point was the special Curtis pot that costs so much money is generally thought not to be of particularly good quality. Over priced too.

He encouraged me to mod a $2 Radio Shack 5k pot instead.

Suggested looking at sizing a pulley to put on the shaft that corresponds to the amount of throttle cable travel. Or using some nylon gears.

Nylon gears, I've got.

For some reason, I'd kept an old, dead inkjet printer in my junk pile. I pulled the cover off this evening, and sure enough there were a couple of 1:4 (roughly - didn't measure exactly) gears inside (paper feeder mechanism).

I cut out the chunk of the printer "chassis" with the gear mounts, modified the shaft of my $2 5k Radio Shack pot to fit into one of them, and presto! It works. And bonus: there's even room inside my forklift potbox for this gear assembly to fit on the end of the throttle arm shaft. The ratio matches the stock shaft rotation and coordinates with the microswitches and physical "stops". Perfect!

Of course by now I could have bought the entire Curtis Company with money earned working, instead of spending all this time trying to track down some other solution, or making my own.

[MetroMPG]

More pics:

(Clicky, zoomy.)



Above: the modified potbox showing the hunk of inkjet printer chassis holding the nylon gears between the actuator shaft and the $2 Radio Shack pot (plus some custom metal work for mounting everything ). Spooky how well it all fit together.

No potboxes were harmed in the hacking of this mod. Its fully reversible should we want to reinstall the forklift pot again for use with the forklift's EV-1 controller.



Installed in the car (well, "positioned" is more accurate. Needs a few more self-tapping bolts to call it "installed"). Throttle cable travel very closely matched the travel of the potbox actuator arm. Just needed to back off the throttle stop inside the car a little bit to give the cable the needed range.

The actuator arm has physical stops at "off" and "full monty". There's also a second set of stops in the internal mechanism. The return spring is also internal - we'll probably add a second on on the actuator arm.





Made cardboard mockups to play around with battery positioning (total box height = battery height including terminals). Hood reinstalled to test for clearance (about 1 1/2 inches). It's like the car was specifically built to accept 4 golf cart batteries with an inch or 2 of clearance all around. Nice.

Next step is making battery trays/hold downs. This week my brother and I are going to look at welders.

[MetroMPG]

SW makes me blush:

Very, very nice. I am properly impressed. You do make it look easy.

[MetroMPG]

(Is it news to say "no news"?)

Nothing to report this week/end. Didn't get a welder. The weather has put a serious crimp in my desire to do a quickie road test. And I have a cold.

Spent a little time looking for angle iron for battery trays. A free bed frame would be nice (though I know some EVers say "proper", thicker angle iron is preferred). Had a couple of leads through the local freecycle group, but nothing just yet.

[MetroMPG]

RH77 chimes in...

Creative
Nice job it looks like it's coming together! Any thoughts of mounting some batts in the rear for weight distrib?

[MetroMPG]

Yeah, definitely. Remember the batts we have are 6v, so those 4 in the front represent only 24v of our 48v goal. So we'll be putting 4 in the hatchback, or under the rear seat if there's enough room - we're thinking of making a batt box that extends down into the space that the gas tank will be vacating. Probably not enough room though.

[MetroMPG]

Comments about using bed frame...

Bed frame sounds perfect to me, good reuse of materials and plenty strong.

I did that once and learned afterwards to make sure the angle iron isn't plated with zinc or something before starting to weld; it can produce poisonous gases.

Yes! I actually learned about that this summer when researching building my bicycle trailer (from zinc coated electrical conduit).

Breathing the fumes can give you "metal fever".

It's better done outdoors, with a good breeze. (Or not at all.)

[MetroMPG]

Hadn't talked to Ivan for about a week or thereabouts.

Turns out while I was tracking down a bed frame (got one this week) he was too. (Actually he got some thicker angle iron).

Word is he's already cut the pieces for the front batt trays and he's going to try to have a friend weld them together tomorrow.

Ah well, we'll likely still be able to use the bed frame metal for the rear tray.

[MetroMPG]

Supposed to be working on the batt trays with Ivan this weekend.

One good note: the freebie batteries which we got (and recharged) back in January apparently are still holding their charge. Checked them yesterday.

Still haven't load tested them, but they've now passed two tests: accepting & holding a charge.

I'm going to contact my guy at the forklift company and see if he has any more trade-ins coming in. I'm sure we'll find some weak ones in our current batch when we start loading them up, and it would be nice to have some back ups.