# Anyone have a 72 volt controller?



## frodus (Apr 12, 2008)

72V sounds kinda low for a car.... its not going to be neck breaking speeds.

Does the controller you have have a current limit in place?

600A on that thing is absolute max, something like 400 for 2 min and 300 continuous... but you should see some currents above 300. Your gauges might average the levels, so you may never see the spikes.


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## VDubber (Jun 2, 2008)

What is the motor and the batteries being used? What are the guage of wires that are feeding the motor and controller? What voltage exactly do you read under full throttle?

Perhaps you are hitting a current bottleneck somewhere else in the system...

But the recent crop of "My Kelly does not put out much power and blows her top easily" are starting to make me reconsider my initial shopping list.


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## frodus (Apr 12, 2008)

well, they're not isolated, they're low power but say they're 600A, people have issues wiring the throttle, they've had issues going to the higher voltages (144V).....


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## adric22 (Jan 17, 2008)

VDubber said:


> What is the motor and the batteries being used?


Batteries are Trojan T-875, motor is a D&D ES-15a (10 HP continuous, 40 peak)



> What are the guage of wires that are feeding the motor and controller?


They are 2/0 stranded (welding wire)



> What voltage exactly do you read under full throttle?


Under full throttle, normally it reads about 62 to 64 volts.


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## Batterypoweredtoad (Feb 5, 2008)

Have you tried a full throttle run from a standing start in 4th gear? From the few motor graphs ive seen, not many motors will pull more than a few hundred amps through very high rpms when driven by 72V. You would have to lug it hard to get the high amp situations on only 72v.


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## adric22 (Jan 17, 2008)

Batterypoweredtoad said:


> Have you tried a full throttle run from a standing start in 4th gear?


No, I haven't tried that. I'd be afraid I'd burn something out. (probably the motor)


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## VDubber (Jun 2, 2008)

Good point. To get the motor to draw more amps, you need to upshift sooner (or start out in a higher gear). Many people seem to start in second gear, and shift to 3rd at 20-30MPH.


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## Batterypoweredtoad (Feb 5, 2008)

Found this:
* Q:  In reference to shifting vs. not-shifting. What is the practical RPM range, and could a tachometer be useful in deciding when it is appropriate to switch gears? 
* *A: * With our ES-15A D&D Motor that is used with Kit #1 & 2 at 80 lbs torque the RPM of this motor is 1616. At the other end of the spectrum at 2 lbs. of torque the RPM is 5686. Most the time it will be running around 2700 RPM using 25 lbs of torque. At that point it is drawing around 175 amps. Shifting gears it feels pretty close to a normal standard clutch car. So it isn't hard to tell when you want to shift. With our ES-31B D&D Motor that is used with Kit #3 & #4 at 80 lbs torque the RPM of this motor is 1386. At the other end of the spectrum at 5 lbs. of torque the RPM is 3831. Most the time it will be running around average 2287 RPM using 25 lbs of torque. This is running it at 72 volts. Volts do make a difference so at 72 volts with this motor it will do 80 lbs of torque and at 144 volts it doubles at 160 lbs of torque.


Found here:
http://e-volks.com/questions.html


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## 3dplane (Feb 27, 2008)

Adric22!
I think you are doing pretty good for a 72 volt system. A member here Coley runs an alltrax 7245 in his Yugo with nearly identical top speed as yours.I think he limited his current draw to 200 amps, and draws about 100 amps at 40 mph. another one is Dr Larry with his metro running a 7245 and if I remember correctly his max amp draw going up a hill was 230A. Now he runs 84 volts with the same setup and can hit 70mph freshly off the charger.BTW isn't that kelly good for 84 volts? That would help with pulling more amps on take off. I run a 7245 in my golf cart and able to pull 235 amps for a split second on take off (but in the next two seconds its down to about 60 amps because its going 20+mph and I can't shift) I'm sure glad for these kelly threads popping up because now I have a different view on them too.Thanks Barna


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