Hit the EV conversion motherlode

[Wonderboy]

what are your goals (range/speed)?

I plan to achieve 45mph max and hoping for something like a 20-40 mile range, but I think this could go higher. It's going to be a simple around-town car that I would need at minimum to do a 20 mile round trip at best, but I would like to go a little further if I think of other errands to run on that worst-case scenario trip.

So what are the Volt and Amp ratings on the motor? Also, how much does the vehicle itself weigh, how much hauling load is it rated for and what is it's maximum rated speed at 72V? How many Amps is the Controller rated for, and does it have a variable Voltage or a single 72V rating?

The motor is rated at 36-72V, 6 HP, 27 HP peak. Don't know the amperage.

I have no clue what the vehicle weighs, its pretty light. I'd guess less than 1000 lbs. It is NOT very fast, but this is in part due to the tiny little wheels, and the fact that it was designed to run indoors at a manufacturing plant - it's not supposed to go fast. I took it up an incline and it did not do well - it slowed down considerably, but it did still make it eventually. I hope this means the batteries are still in okay shape.

About those batteries... they are all 6v, so this thing was mis-advertised on CL (although I don't blame the guy). The motor is running at its rated 36, so I don't know how it will act with 72, nor do I know what I'll do about the battery situation.

I haven't taken a look at the controller - one thing I know is that there are (as TomEV mentioned) 3 "speeds" based on pedal position, and 3 corresponding coils under the seats that get VERY hot.

Any news? Has the Great Tear Down begun? Found a recycler to take the bones off your hands and recoup some of the cost?

I've actually been unusually busy lately making money or whatever - some old BS :-P In light of my slightly unfortunate battery diuscovery, I'm going to wait to tear it apart until I:
1.Get a better look at the controller and find out if it has a voltage rating and/or a governer on it and get that removed.
2.Get more batteries and run it with more batteries on it to see how fast it goes

I'm still looking for a host car, but no rush on that.
more to come,
will

[MetroMPG]

Oh! Sounds like you've got a simple contactor controller, with possibly 1 speed wide open (direct connection) and two lower speeds "controlled" with some combination of the resistors (potato boilers, as some of the Citicar people call them).

I thought you had a PWM controller.

[TomEV]

Depending on your tolerance for 'possible' burn-out of components, since you appear to have a contactor set up it will be easy to test it at a higher voltage. Coil -type contactor setups normally do not have a series/parallel system, and run the full pack voltage through the resistors (coils) to move at slower speeds.

Other, obsolete 3-speed contactor systems use 2 batteries (low, 12v) 4 batteries (med, 24v) and all batteries (high, 36v). You probably don't have this type of setup because you have resistor coils.

The most sensitive part will be the contactor coils (part that pulls the contactor closed, not the resistor). If they are running at 36v (full pack voltage) they won't like to be operated at 48v or 72v and will tend to burn out very quickly. If you can trace back to where the contactor coils get their power, you can re-tap the traction pack at 36 (or 12 , or 24v, whatever they use) to make them work with a higher voltage pack. The two or three amps won't be a significant mismatch across the battery pack considering your motor uses about 150 amps.

Aside from that, you can temporarily install old 12v car batteries for a test to see how it will do. 4 for 48v, and 6 for 72v. You may be able to sweet talk a junk yard or battery store into 'borrowing' a few old batteries for a test before you buy a whole new set...

One last note - If you replace the batteries with a higher voltage set, check where your 12v power (lights, etc.) comes from before you turn anything on. In many utility carts, 12v is tapped off from two of the traction batteries. You won't want to put 24v to your headlights!

[Christopher Jordan]

Originally Posted by TomEV

If memory serves, they were made by taylor-dunn

... and maybe when it grows up it can impersonate this beauty! Taylor-Dunn I think:

[Wonderboy]

So here's a general good-to-know question: In a host car where I intend to use an existing transmission, what would be better to look at if I'm looking at cars with virtually the same curb weight - more torque or less torque? It just crossed my mind how light those older 3 series BMWs are, and how light they would be minus their HUGE engines. Would this be a bad transmission to work with, or better to propel the car up to my low top speed goal? The pickins are slim for little cars around here like metros, MR2s, CRX, and even the less "famous" ones. I did find a $150 97 metro lsi hatchback shell sans tranny - I am carefully considering this because it would save me the work of ripping an engine out, and all I would have to do is go to the junkyard for a similar transmission. (The problem is that I'd have to take another long road trip to go get it.) Would a transmission like the metro's be better for an underpowered motor like the one I plan to use?

[dcb]

hmm..., what is the track width of that material handler? I'm wondering if you can just graft the drivetrain/wheels/suspension off that on to the rear underside of the lsi? And have more room for batteries under the hood.

Potato boilers, lol.

[Wonderboy]

The track is pretty thin, probably even thinner than a metro wheelbase. Even if I could get that to work (since the drivetrain is pretty small on the cart) it's geared so slow with only one gear (and I doubt it's CVT :-P) that i don't know if I could convince it to go as fast as I want nor up hills quickly enough to be safe. I will look into this a bit more in depth. I'd still really like to know if anyone has ideas on the optimal transmission for my application.

[dcb]

fyi, i just measured a 98 metro, it was ~59 inches wide at the rear as measured at the outside of the tread.

$150 for a metro if it has a clear title would be a pretty good starting point. You can also experiment with your existing cart a bit too, like weigh it down to as much as a metro and see how it performs.

[MetroMPG]

Do you actually have a lead on an old BMW? I didn't think they were very light (of course, you know my reference point).

As for transmission choice, unless you're planning a drag car I don't think you need to worry about the torque capacity of one over another. It shouldn't sway your decision all else being equal, I mean.

[Wonderboy]

old 3 series BMWs are actually easier to find around here (on CL) than typical EV conversion finds. As for that metro lead, I'm going to wait on that, because I don't think many people would bite. If they do, I'm not too concerned, something will come up eventually. Today I actually got not one but TWO CRX leads. One is $100 and the other could be free or equally as cheap. I know I'm going to be able to get a sweet deal on whatever my host car will be, so I'm anxious to bite, but not in a hurry. Still haven't made it back up to parents house to measure the wheel base. I appreciate all the input and feedback, guys.