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[Noleander]

Hello everyone, I am new to these forums, so I thought I'd introduce myself and my EV.
I converted my 1985 Honda Interceptor VF700F back in 2010 and have been regularly making changes to increase its performance. Below is a list of the currently installed parts:
K91-4003 Advanced motor- 5:1 gear ratio currently, but performed well enough at 3.84:1 ratio
Soliton Jr. (yes, I know it's a big controller for a motorcycle)
36*CALB 40Ah cells, configured 36s1p
Elcon 1500 charger
JLD404 intelligent Ah meter with shunt - interfaced with the Elcon to shut off charger @ 123 volts to protect cells; this is my method of battery management, which works fine so long as I don't discharge at over ~325 amps pack current.
No DC/DC, just using 4*40Ah Thunder-sky cells that failed miserably as a traction pack because they were built so poorly-they work fine at very low (<1C) discharge/charge rates.

City range (45mph): 33 miles-ish (142 calculated wh/mile
Highway range (63mph average): 26 miles-ish (180 calculated wh/mile while on a trip with 2out of 6 miles up a 4% grade @ 65mph)
Acceleration 0-60mph: 7.783s best time yet with 5:1 gear ratio
Top speed: 80mph, limited by motor RPM, with 3.84:1 gear ratio, I hit 87 mph in 14.5 seconds!
I thought I would get more range, but I am pretty throttle happy and don't even need 20 miles range.

I am thinking about upping the voltage to find out how high I can take this little DC motor without hurting it; the highest pack voltage I have fed it thus far is 120 from my current pack. I don't have any over-speeding protection other than my calculation for motor speed vs mph, which limits me to 80mph, but I won't hit those speeds for long (if at all), because I've read that those max motor RPMs are supposed to be for short periods. I also blow out the brush area once a week to avoid brush dust causing conductivity where it doesn't belong.

I can do a burnout, which is pretty cool, but the bike to way to heavy for a wheelie.

I would like to hear from others who have over-volted their motors.

[protomech]

Noleander,

You may have already read it, but check out the Ed and his Juiced racebike on elmoto. esbk.co did a podcast interview with Ed recently after the race, he overvolted his motenergy DC motor and burned it up at race pace, potentially due to lack of cooling.

http://www.elmoto.net/showthread.php?2945-Road-Atlanta-%96-fun-friends-even-some-flames

http://esbk.co/2013/04/29/esbk-studios-post-race-interviews-from-april-29-2013/

[frodus]

It's technically a 72V motor. They have 96V curves for it, but it's still wound as ~72V. You could probably go to 2x the rated voltage, but I'd REALLY suggest advancing the brushes.

[Noleander]

I plan on advancing the brushes, though the motor doesn't seem to mind my current setup-no excessive arcing or heat. As long as I don't go full throttle, the arcing is minimal and I don't get enough range to heat up the motor  enough to get into trouble. Since I rarely go WOT, I feel pretty safe about using the motor as is. I just want to know the over-volting process well enough to speak from my own experience rather what I theorize would happen.

I have also given some thought to the brushes- Helwig claims to make brushes that work better, but after reading their product sheets, I didn't read anything about them that made them seem all that special, though I have read accounts of people switching OEM brushes for Helwigs and experiencing greater motor efficiency (more range).

I have some extra LiFePO4 cells that I can use to test higher voltages on my bike, of course after advancing the brushes.

Thanks for the replies and links

[Noleander]

I've done some reading on advancing the brushes and I now doubt I'll be doing it. My experience tells me that I don't need to, unless I were to increase the voltage even higher. I read an article that was very well written on another forum that explains the loss of torque that would happen (about 2% for every degree of advance) were I to advance the timing. My motor doesn't actually experience a high enough voltage under most conditions (usually half throttle and less) to necessitate the advancing of the brushes.

I blow compressed air into the brush-area once a week and there doesn't seem to be much dust building up even after holding the throttle wide open for longer periods, so I think even brush wear isn't exaggerated much compared to the rated 72 volts. I will catch some video of the brushes under various throttle positions and review it to be sure, but I can look down and see the brushes while riding (at night, the arcing is visible)- yeah, not so safe, but I only do it when I can see for miles and nobody's around me.

[hamr1]

To be honest i do not really see the point in just throwing more voltage at the thing
Helwigs may improve performance depending on your application

[Richard230]

They are going to love you over at:  http://www.elmoto.net

[Sarge17]

I have a 2011 Zero S, I've NEVER used WOT, I've used brushed AC motors for years and noticed that brush arcing and wear is directly related to load. I am only interested in distance and longevity, so no need for WOT and increased wear and tear. Sarge