Citicar - from 48v to 64v

[MetroMPG]

Oh, I don't know about that.

Want to do a virtual drag race?

[MetroMPG]

3) How fast does it go?
It’ll hit 50 km/h (30 mph) in normal driving just fine, but it doesn’t get there particularly quickly. On a fresh charge it takes about 21 seconds to hit that speed. My 7 year old nephew could out sprint the car in a drag race for a good 5 car lengths!

Three Dirt Cheap DIY Electric Cars – Part 3

That's flat out, probably a 3rd gear start (I forget whether I had yet learned that it accelerates better in a higher gear), with a 400A controller.

[TomEV]

Virtual Race Info:

With my Citicar at 48 volts, it would accelerate like this:
0-25 ~ 6.5 seconds.
0-32 ~ 16.0 seconds

With a top speed of about 37 MPH field weakened. I estimate that the 48v 1/8 mile time/speed would be about 19 seconds @ 36 MPH.

>>>>

At 64v, I rarely use FW as it accelerates just fine without it. It gets to 40 MPH as well as a normally accelerating IC vehicle, and does about 42 or so without FW.

One nemesis was the tunnels leading in and out of Alameda. The speed limit is 45, and at 48v it would get there reasonably well (going downhill...) and was able to hold 45 on the floor of the tunnel with FW on. Going back out (uphill) was another matter. Even with FW on, the speed wold decay to about 30 to 32 MPH. With FW off, it would probably decay to about 27 MPH. Once outside the tunnel on level ground, it would take a while to accelerate back to about 35.

At 64v, the speed downhill and on the floor, without resorting to FW are the same as I limit it to about 45 to keep from over-revving the motor. Going uphill, it now maintains 40 with FW on, and gets back to 45 once out of the tunnel quite easily.

[MetroMPG]

Well, not only is your car more functional now, you won the virtual drag race even before upgrading!

The ForkenSwift suffers from a pretty significant weight disadvantage though: 2070 lbs, empty, vs the Citicar's 1300 lbs.

[TomEV]

But at least ForkenSwift doesn't rain inside when it is raining outside! The old-school 'side curtains' keep some of the wind out, but I really don't like to drive the Citicar in rainy weather.

[MetroMPG]

You're right - the rain doesn't come through the windows of the ForkenSwift.

It comes through the Flintstones-style holes in the floorboards in the form of road spray.

[Ryland]

That is why I really like the Commuti-car doors with their solid windows that slide instead of being removed to open them, they are pretty decent in the rain, humidity still builds up in the car, part of why I got a small dehumidifier that I plug in.
Tom, any idea if my 6hp motor is really any bigger then the 3.5hp motor you have? I have a "low speed" rear end so my top speed is also about 35-37mph at 48v but I feel like I accelerate pretty well.

[TomEV]

The GE 3.5 and 6 HP motors are virtually the same electrically - Same field shoes, same brushes, same armature windings. Main difference is the armature shaft is male on the 3.5, and female on the 6. (there are a couple of other structural differences so they mate properly with the Terrell or Dana axle).

They have different ratings because the 3.5 is a 'closed' motor (no ventilation) while the 6HP has a cooling fan.

The high speed is mostly limited by the amount of RPM you can attain before counter EMF forces self-limit the motor RPM. 35 to 37 MPH is what I would expect in a stock Comutacar/Dana axle, and about 32 - 34 in a Citicar/Terrell axle. Ways to decrease counter EMF force is to use field weakening (weakened counter EMF, allowing the motor to turn faster at the top end) and/or increasing the voltage. Going to a higher amperage controller only affects low speed acceleration, as these motors can only use over 400 amps up to about 1,000 RPM.

You'd probably only notice the difference in speed and acceleration if you broke out the stop watch and timed a 48v Citicar and a Comutacar zero to top speed. Do you have any 'virtual drag race' numbers for your Comutacar? With the Comutacars I've driven, (sample of two) I found them to be somewhat slower to accelerate - but very much quieter. My 'silent' EV is anything but! I am very jealous of the Dana axle... Imagine a '30's pickup in granny low - and then put that gearbox sound in a plastic car, going 35 MPH.

Replacing the transaxle was one reason why I got a basket case Comutacar - unfortunately, someone had modified the transaxle with 12:1 ring and pinion - not terribly useful. I donated the Comutacar to the local high school for a project/instructables car as it didn't have any of the body panels, and was missing too many parts to make it into a road worthy vehicle.