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[Axelwik]

I just joined the forum.

Picked up a rolling chassis the other day (Suzuki Katana) and plan to use LiFePO4 batteries, but can't decide whether an AC induction motor or series DC motor is the right solution. Is the AC motor worth the extra cost (prices have seemed to come down)? I don't want to spend a fortune, but I'm not poor either. My goal is a bike that will have a range of 60 to 100 miles and a top speed of 100 MPH. I have $4,000 to $6,000 to spend. I'll do all the work myself. Am I far off the mark?

[frodus]

6-8k probably won't get you that range. Expect to spend 6k just to get to the 40 mile mark. 100 miles is going to cost you much more.

I'd recommend going AC if you want to get anywhere near 100mph and that type of range, due to its wider RPM range and higher efficiency.

Batteries are going to run you between $3 and $4k for decent batteries with high enough power to get you to 100mph, and even then, thats only 6kwh. Note that the faster you go, the more power you draw and less range you get.

You'll need a BMS for them, expect to spend anywhere between $400 and $1000 for that.

AC motor and control will be over $3k

Contactor another $100-150

DC-DC converter another $150 or so

Charger another $500 or so

Cables, wiring harness, any extra gauges you might want, add another $200-500

New rear sprocket $100

New chain, front sprocket $50-100

I'm into mine for about 8-9k right now including chassis.
Specs:
192 Headway 38120S cells
Elithion BMS
AC-15 and a Curtis 1238-7501
Vicor DC-DC converter

[Axelwik]

For that kind of money I might as well reserve one of the 100 MPH Brammo bikes coming out next year. How do they do it so cheaply then?

[Axelwik]

Another question:

With an AC motor and controller, for example your AC-15 motor with a controller DC input of between 48 and 84 volts, does the input voltage matter in terms of motor output power and torque (as long as it's between 48 and 84 volts)? It seems to me that the controller, having an integrated inverter, would put out the correct AC voltage, phase, and amperage that the motor needs, right?

[frodus]

For that kind of money I might as well reserve one of the 100 MPH Brammo bikes coming out next year. How do they do it so cheaply then?

Yup.

How do they do it so cheaply?

http://en.wikipedia.org/wiki/Economies_of_scale

[frodus]

Another question:

With an AC motor and controller, for example your AC-15 motor with a controller DC input of between 48 and 84 volts, does the input voltage matter in terms of motor output power and torque (as long as it's between 48 and 84 volts)? It seems to me that the controller, having an integrated inverter, would put out the correct AC voltage, phase, and amperage that the motor needs, right?

Yes. It pushes out the torque a little further on the RPM curve. Going from 48V and the 550A controller, to 84V and a 550A controller you almost double power. And BTW, the voltage on the 1238-7501 can go up to 130V off a fresh charger. I'm building mine for 102.4V nominal (32s6p).

The controller takes in pack voltage and converts that to the requested load on the AC motor at a certain Frequency. Higher frequency, the higher the RPM. Everything is done automatically, but its not trivial. The controller has algorithms inside to calculate voltage, current and frequency.

[Axelwik]

Another question:

With an AC motor and controller, for example your AC-15 motor with a controller DC input of between 48 and 84 volts, does the input voltage matter in terms of motor output power and torque (as long as it's between 48 and 84 volts)? It seems to me that the controller, having an integrated inverter, would put out the correct AC voltage, phase, and amperage that the motor needs, right?

Yes. It pushes out the torque a little further on the RPM curve. Going from 48V and the 550A controller, to 84V and a 550A controller you almost double power. And BTW, the voltage on the 1238-7501 can go up to 130V off a fresh charger. I'm building mine for 102.4V nominal (32s6p).


The controller takes in pack voltage and converts that to the requested load on the AC motor at a certain Frequency. Higher frequency, the higher the RPM. Everything is done automatically, but its not trivial. The controller has algorithms inside to calculate voltage, current and frequency.

Thanks. I'm now thinking about using a DC motor to save some money (maybe). I'm just going to have to do some more reading before investing the money. I want to make sure everything works together in the most efficient way possible.

[frodus]

DC would be a good start, especially if you used a 6.7" motor with the same face mount as an AC motor you might "upgrade" to. They'd be fairly easy to resell too.

Series wound ADC k91-4003 motor with a Synkromotive controller is what I started with, and went to the AC15.

[Axelwik]

DC would be a good start, especially if you used a 6.7" motor with the same face mount as an AC motor you might "upgrade" to. They'd be fairly easy to resell too.

Series wound ADC k91-4003 motor with a Synkromotive controller is what I started with, and went to the AC15.

Did the ADC motor and Syncromotive controller work well together?  Any issues in terms of setup, reliablity, etc?

[frodus]

Yes, the ADC motor and Synkro contorller were great, but you can't get the Synkro controllers anymore. It'd be great paired up with an Alltrax, Curtis or a really high current Kelly controller.

look at my website for all you ever needed to know about the conversion....

www.evfr.net

*hint: go to the "archives" on the right side, drop the pulldown menu and start at the beginning (august 2007)

[tomaj]

Hi,I am from Slovenia and this is my first post on this forum

So I am building up electric powered motorcycle on Hyosung GT250 base.
I will use Kelly controller and 72V 100Ah LiFePO4 batteries.
I want max. speed 100-130 km/h and range around 100km.

Which motor is the best choice?
http://www.kellycontroller.com/mars-3001etek-comparable-pmsmbldc-motor-p-29.html

or

http://www.goldenmotor.com/   (5kW BLDC motor)

Or maybe some other brand?