DC motor questions....

oscarvan · 04-13-2013, 03:59 AM

Once again, I'm on this forum as none of the others get close to what I'm doing....

(see here:http://www.buggiesgonewild.com/extre...art-frame.html)

Now, this creation will have to go as fast as I can walk, say 3 mph.

I have the old style copper coil resistors. Talking to Greg at Vintagegolfcartparts.com he said that running the unit in slow gear for a long time (long being 15-20 minutes) would heat up and then fry the resistors.....

I have come up with two solutions, and I hope there are seriously electrically savvy people here to test these ideas...

1 Get a real resistor. The motor is labeled to be 55A at 36V which gives 12mph. The theory is that to reduce that to about 3mph I would run 55/4=14A (rounding up) Since: V=A*Ω 36=14*2.6..... so (again rounding up) lets get a 3Ω resistor, that can handle 36*14=504W.....

So I found this..... http://www.newark.com/ohmite/tap600k...+600w+resistor

My thinking is, that one of these instead of the coil resistor and the speed selector, so direct wire, would give me about 2.5 mph, and that it would not fry the resistor. Am I thinking straight?

Plan 2: I notice many here are going to 48V on a 36V unit to squeeze out a ferw more mph. Does it then follow that if I put a few 12v batteries in parallel I would get 36/12=3 miles per hour? Would this hurt the motor?

I can try this first to see how it works before I plop down a hundred bucks for a resistor.......

oscarvan · 04-13-2013, 06:08 AM

Edited.....I need to put the 12V batts in parallel, not series, to get 12 volt to the motor instead of 36 and thus get a third of the speed....

kab69440 · 04-13-2013, 06:43 PM

In theory, yes. Keep in mind though, the motor will pull a lot more amps on 12v to move the same weight than on 36v. I think I personally would be looking for some kind of gear reduction.

oscarvan · 04-14-2013, 02:01 AM

Understood. Weight will be a lot less than a fully loaded golf cart though. ......

Andy4639 · 04-15-2013, 06:28 PM

I don't think 12 volts will move a motor that is designed for 36 min. As a rule of thumb it's always better to go more but never less. 36 volt cart want move at all under about 30 volts.
I would scrap the resistors all together. They are old school and fire hazards! Buy a controller and it want care if your wide open are barley moving. Fix the gas handle where you only can go so fast. Another thing is make sure it has the Ragen brake workable so when you let off the gas handle the motor will come to a stop. Call Alltrax they should help you out.

04-13-2013, 03:59 AM	#1
oscarvan Not Yet Wild Join Date: Apr 2013 Posts: 25	DC motor questions.... Once again, I'm on this forum as none of the others get close to what I'm doing.... (see here:http://www.buggiesgonewild.com/extre...art-frame.html) Now, this creation will have to go as fast as I can walk, say 3 mph. I have the old style copper coil resistors. Talking to Greg at Vintagegolfcartparts.com he said that running the unit in slow gear for a long time (long being 15-20 minutes) would heat up and then fry the resistors..... I have come up with two solutions, and I hope there are seriously electrically savvy people here to test these ideas... 1 Get a real resistor. The motor is labeled to be 55A at 36V which gives 12mph. The theory is that to reduce that to about 3mph I would run 55/4=14A (rounding up) Since: V=AΩ 36=142.6..... so (again rounding up) lets get a 3Ω resistor, that can handle 36*14=504W..... So I found this..... http://www.newark.com/ohmite/tap600k...+600w+resistor My thinking is, that one of these instead of the coil resistor and the speed selector, so direct wire, would give me about 2.5 mph, and that it would not fry the resistor. Am I thinking straight? Plan 2: I notice many here are going to 48V on a 36V unit to squeeze out a ferw more mph. Does it then follow that if I put a few 12v batteries in parallel I would get 36/12=3 miles per hour? Would this hurt the motor? I can try this first to see how it works before I plop down a hundred bucks for a resistor.......
oscarvan Not Yet Wild Join Date: Apr 2013 Posts: 25

04-13-2013, 06:08 AM	#2
oscarvan Not Yet Wild Join Date: Apr 2013 Posts: 25	Re: DC motor questions.... Edited.....I need to put the 12V batts in parallel, not series, to get 12 volt to the motor instead of 36 and thus get a third of the speed....
oscarvan Not Yet Wild Join Date: Apr 2013 Posts: 25

04-13-2013, 06:43 PM	#3
kab69440 Gone Wild Join Date: Aug 2010 Location: Marion, Ohio Posts: 1,391	Re: DC motor questions.... In theory, yes. Keep in mind though, the motor will pull a lot more amps on 12v to move the same weight than on 36v. I think I personally would be looking for some kind of gear reduction.

04-14-2013, 02:01 AM	#4
oscarvan Not Yet Wild Join Date: Apr 2013 Posts: 25	Re: DC motor questions.... Understood. Weight will be a lot less than a fully loaded golf cart though. ......
oscarvan Not Yet Wild Join Date: Apr 2013 Posts: 25

04-15-2013, 06:28 PM	#5
Andy4639 48/400/Alltrax HS motor Join Date: Jan 2007 Location: Liberty SC, Garden City SC Posts: 6,190	Re: DC motor questions.... I don't think 12 volts will move a motor that is designed for 36 min. As a rule of thumb it's always better to go more but never less. 36 volt cart want move at all under about 30 volts. I would scrap the resistors all together. They are old school and fire hazards! Buy a controller and it want care if your wide open are barley moving. Fix the gas handle where you only can go so fast. Another thing is make sure it has the Ragen brake workable so when you let off the gas handle the motor will come to a stop. Call Alltrax they should help you out.

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