# Motor Heats up more after advancment , is this normal?



## imaspaceguy90 (Dec 14, 2008)

Hey guys, after confirming with the guy i bought my motor from that the motor is neutraly set, i decided to advance the motor 12 degrees for 144v capability. i installed the motor and hooked it up to a 12v battery in neutral. It sounds like the RPMS are a little higher, but not to much. There is deffinetly a diffrence then in reverse.

My problem is that my jumper cables seem to get a little bit warm, and i dont rember them getting warm at ALL Before the advancment. Could this be because of the extra few rpms or could it be because its a 12v battery and not a 144v pack and its pulling alot of amps from the battery?
Any help is appreciated. Thanks- Zach


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## Guest (Jan 26, 2009)

Well when you are using jumpers and a 12 volt battery you are pulling full amps and because your motor is now advanced it will require more amps from that 12 volt battery. It may not be much more than before but jumpers will get very warm if not hot doing things like that. My Starter/Generator motor got my jumpers hot when I was testing directly from the battery. It just pulled a ton of amps. Jumpers are not designed to do that. They are meant to jump start a car. Even if you use jumpers to start another car you can pull enough amps over time if the jumped car does not start and you keep running your starter. It is just like running your motor for testing. Run like that for any length of time and you run the risk of toasting your jumpers. If you can use 2/0 cable to test with. They can handle that load better. 

Pete : )

Lets ask Jim Husted if advancing the motor will actually cause it to pull more amps. I say yes until you are up and running. By advancing you actually loose low end power and that may make the motor want more amps to compensate. But at higher speeds it will be more efficient and you should pull less. There is always a trade off when you change timing. This trade off will allow you to run more voltage safely. 





imaspaceguy90 said:


> Hey guys, after confirming with the guy i bought my motor from that the motor is neutraly set, i decided to advance the motor 12 degrees for 144v capability. i installed the motor and hooked it up to a 12v battery in neutral. It sounds like the RPMS are a little higher, but not to much. There is deffinetly a diffrence then in reverse.
> 
> My problem is that my jumper cables seem to get a little bit warm, and i dont rember them getting warm at ALL Before the advancment. Could this be because of the extra few rpms or could it be because its a 12v battery and not a 144v pack and its pulling alot of amps from the battery?
> Any help is appreciated. Thanks- Zach


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## Guest (Jan 26, 2009)

Did you advance according to the information on Jim Husted's site?

Pete : )


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## hidbulb (Jan 26, 2009)

I guess it happens when you upgraded it....


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## imaspaceguy90 (Dec 14, 2008)

gottdi said:


> Did you advance according to the information on Jim Husted's site?
> 
> Pete : )


Hey pete, I couldnt find any info on the actual advancment. I measure 12 degrees and mounted the brush holder there. The brushes look to be about the same distance from the pole shoe bolts as Jims was. You think its normal or you think i got a problem? I dont see any arcing with my eye. The only time i saw arcing was when the motor was reversed. Should the copper wiring coming out of the brushes be a tad warm as well? I ran the motor for about 2 minutes and the brush wires were a tad warm and i felt the commutator bars and they felt warm as well.


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## major (Apr 4, 2008)

gottdi said:


> Lets ask Jim Husted if advancing the motor will actually cause it to pull more amps. I say yes until you are up and running. By advancing you actually loose low end power and that may make the motor want more amps to compensate. But at higher speeds it will be more efficient and you should pull less. There is always a trade off when you change timing. This trade off will allow you to run more voltage safely.


Hey Pete,

I don't think Jim will mind if I address this.

Yes, advancing the brushes will cause the motor to pull more amps at the same load. It has the effect of field weakening. This reduces the torque per amps across the whole range and increases the RPM at medium to light loads. It might increase efficiency at light loads, but will not pull less amps. It will run faster and increase power out that way, not reduce current at a given torque.

Regards,

major


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## major (Apr 4, 2008)

imaspaceguy90 said:


> i felt the commutator bars and they felt warm as well.


Hey dude,

Keep your fingers off the commutator surface. Even the slight oil from your skin is not good for the proper copper/carbon film needed for good commutation and brush wear. If you must read comm temperature, get a noncontact thermometer.

Regards,

major


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## imaspaceguy90 (Dec 14, 2008)

Point taken Major.


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## ice (Sep 8, 2008)

Hi Major,
How many percent would this reduces the torque per amps?


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## major (Apr 4, 2008)

ice said:


> Hi Major,
> How many percent would this reduces the torque per amps?


Hi ice,

I doubt there is a clear number you can put on it. Different motor designs and I don't think it is a linear relationship. But, what the heck! Here goes.

The torque is the cross product of the vector quantities of the field flux and armature mmf. This means that torque is a maximum when those vectors are at 90 degrees and torque is zero when they are aligned. And varies by a cosine relationship.

Skipping the trigonometry. For these 4 pole motors, torque per amp is the greatest when the brushes are on neutral. And zero when shifted 45 mechanical degrees. So, for a rough approximation, call it 2 percent per degree. That would be a 2 percent reduction of torque per amp for every degree of brush shift from neutral.

That would be my best guess without doing actual dynamometer tests or finite element analysis of the magnetics. If anyone else has experience, please chime in.

major


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## ice (Sep 8, 2008)

Oh I see, Thanks!


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