[hppyfngy]

Hi, nOOb here.

I have a Ninja 250 as a donor bike. I want to build a relatively simple inexpensive EV as a starter. Range 10-15 miles, maybe less. Speed 30mph.



I am a pretty good mechanic if I have instruction, but don't know a lot about electronics. Weld some with mig and oxy/acetylene. Still learning...

So, where would you have me start?

Oh and this is my inspiration. My 1973 Auranthetic.



Thanks,
Randy

[kek_63]

Why don't you pop in at www.elmoto.net . It's an EV forum dedicated to motorcycles. There are a number of 250 Ninja conversions going on there.

Keith

[BradQuick]

I have a Ninja 250 that I've converted. Why settle for 30 mph, when you can fairly easily do 50 mph?

I'm using six B&B 35ah deep cycle AGM batteries, a Perm 132 motor and a Kelly 72v, 450 amp controller.

The bike is a little heavy, but it's a lot of fun. It will do 54 mph off the charger and 52 after 10 miles. Useful range is 15 miles when travelling around town at 40-50 mph.

This is a link to my build. I later switched to lead acid batteries and I ended up fixing the perm motor after they sent me a new rotor for nothing.

http://www.endless-sphere.com/forums...p=67172#p67172

[hppyfngy]

As I research it, I'm beginning to see the initial expenditures will be the largest, and I probably won't limit the build to a 30mph goal.

But, I may have to add components as $$ permit.

I have heard the heat may be an issue with this motor if I tried to run it at 72V. Also, the controller in this "kit" is 24-48 Volts/300 amp. Am I going to be really disappointed if I don't spend the $150 more for the 24-72 V/400 amp controller?

Also, I'm on the fence about batteries. Voltage and type.

What's the best bang for the buck nowadays? Remember, this is a toy for me, not even a commuter. A grocery getter. I don't need great range or speed, although more is always better, no?

Thanks for the link...

[Drew]

you might be interested in something like these

http://www.thunderstruck-ev.com/AC_d...erformance.htm

I don't know if anyone on here has used them but they're very cheap for AC and give you a much wider operating range which means better performance, AC is also typically a lot more efficient than DC

[hppyfngy]

don't confuse me...

[Qer]

Originally Posted by hppyfngy

don't confuse me...

You better not get confused since that's mainly bollocks anyway. It's true that AC motors are more efficient than DC but on the other hand DC controllers are more efficient than AC ditto so the difference won't be that big in the end, and with lead acid (which I presume you'll be using?) your main problem with efficiency will be the batteries anyway (because of peukert effect).

Also, for example a 20 kW AC motor and a 20 kW DC motor still gives 20 kW (duh), it's just that the AC motor will give more RPM where the DC motor will give more torque (since power = rpm * torque) and while the DC system will typically demand more current a AC system will demand more voltage (since power = voltage * current).

Get a motor that fits your frame, your wallet and that has a reasonable system voltage. AC or DC are just different technologies, it's simply not possible to claim that one technology is "best" or gives "better performance". It's like claiming that V-motors are always better than inline motors or that cake is better than pizza. Besides, I bet the pack will be the bottle neck anyway.

That said, those motors do look interesting. If they're better or worse than a DC system, well, that depends on WHICH DC system you compare with. Of course.

[Drew]

Qer, I was under the impression that a matched set for an AC system was around the mid 90's region in terms of percentage efficency. Being that the Perm 132 motor has a peak rated efficiency of 86% at rated voltage and 88% at 72V that would mean that a DC controller would have to be about 110% efficient to match an AC system yes?

This isn't the main benefit I see to AC though, the main reason that AC interests me so much is because of the operating range, because an AC motor seems to reach peak power and then continue with overrun it means that you can gear the motor a lot lower than you would a DC motor with a single drive ratio and still get the same top speed. This would mean that you'd get better off the line performance and better responsiveness through the range.

This is just based on the information that you and a number of others gave me during the AC vs DC thread a while back, but I would assume that DC was presented in the best possible light considering that there are a large number of DC proponents on this site

[Qer]

Originally Posted by Drew

Qer, I was under the impression that a matched set for an AC system was around the mid 90's region in terms of percentage efficency. Being that the Perm 132 motor has a peak rated efficiency of 86% at rated voltage and 88% at 72V that would mean that a DC controller would have to be about 110% efficient to match an AC system yes?

Without going into boring math about power electronics (which is Tesseracts domain anyway) I'd say that it might be realistic to expect mid 90's efficiency for the AC-controller on a good day and under perfect conditions, but you'll probably see it drop lower than that when you start to push it (especially at low RPM's where everything dips fast towards 0% efficiency). So if you go find that 110% efficient AC motor I'll see if I can dig up a 110% efficient DC controller.

More seriously, you still can't compare technologies, you have to compare systems. If you say "THIS AC-system beats THIS DC-system" (for example, that AC system you pointed at looked pretty interesting), then I'm all game, but you can't claim that "Apples beat oranges" and hold that as an ultimate proof.

Originally Posted by Drew

This isn't the main benefit I see to AC though, the main reason that AC interests me so much is because of the operating range, because an AC motor seems to reach peak power and then continue with overrun[...]

¿Que?

All systems have peak power, after which the power will start to drop again. Nothing magical going on here.

- You cannae change the laws of physics, capt'n.

One of these days I think I'll have to put that in my sign.

[Drew]

Sorry, I was thinking of permanent magnet AC systems rather than a squirrel cage setup, but the two systems I've found which I have found data for are the AC150 setup and the Azure Dynamics AC24 system and they are 91% and 87% peak system efficiency respectively. AFAIK that is electricity into controller vs mechanical output from the motor.

Either way, the point that I was getting at is that the AC24 for example reaches peak power at 4000RPM or so, but revs out to 12000RPM which means that you can gear the bike to generate something more like peak tractive effort for the tyres and still have enough overrun RPM to achieve a good top speed. From what was said about DC motors it is not possible to achieve such favourable gearing and still maintain a good level of overrun.