# Motor dead AGAIN



## GizmoEV (Nov 28, 2009)

What was wrong with the motor that it had to be rebuilt? Do you have any pictures of it? It is hard to diagnose what the problem is with very little information.

Maybe you are driving it like it still has the original motor in it. You don't want to lug an electric motor. If you do for very long it can over heat so if you are driving around in 4th gear all the time that might be your problem.

Give us a little more information and maybe someone will be able to give you better information.


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## chronoassassin (Mar 3, 2012)

Sorry for the lack of info, kinda new to the whole forum thing. 

All the other times its been rebuild the guy i take it to said it was the brushes were burned up, or broken off, or even the brush holders broke off one time. 

I could believe that i am driving it incorrectly, cause from what i have read and heard others arent having this many problems.

The motor is a D&D motor systems and is rated at 40 HP peak.
also using the ALLTRAX 7245 PWM controller. This controller is rated at 24-72 volts DC and 450 amps.
It is a 72v system, using 9 x 8v lead golf cart batteries from sams club.

I would not consider my terrain as hilly, but there are hills on my commute to work.


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## chronoassassin (Mar 3, 2012)

heres video from one of the times the motor failed.

http://www.facebook.com/photo.php?v=1252916337918


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## GizmoEV (Nov 28, 2009)

chronoassassin said:


> All the other times its been rebuild the guy i take it to said it was the brushes were burned up, or broken off, or even the brush holders broke off one time.
> 
> I could believe that i am driving it incorrectly, cause from what i have read and heard others arent having this many problems.


From that and seeing that it was actually burning I'm wondering if you are running in to high of a gear and pumping extreme current through it for an extended period of time. When I had too high of gearing in my Gizmo I ended up with chipped brushes, lots of brush dust around the commutator which resulted in arching and always a hot smelly motor when I got home after climbing my hill. The sides of the brushes looked like lightening bolts which was likely from the brush leads not able to handle the current so some of it was trying to go through the brush holders.

If your controller is pumping 450A through that motor on every acceleration and holding high currents for much of your drive then you will burn up your motor. Except for short bursts when you need it you really want to keep the current to the motor as low as you can. You do this by spinning it at higher rpms. Don't drive it like you would a regular ICE. If you are staying in town you should not go above 2nd gear. Some conversions even lock the transmission in 2nd. If you can find out the gear ratios in your trans-axle you can calculate the motor rpm for a given gear and speed.

You really need to get an ammeter in the motor loop so you can see exactly how much current you have going through it. I would recommend getting a 500A shunt and a meter to match it. If you already have an ammeter in the battery loop you can add a shunt in the motor loop and wire it through a toggle switch so you can switch between battery and motor current and see what is going on.

500A meter: http://www.kta-ev.com/Westberg_Ammeter_A2C6_30_p/a2c6-30.htm

500A shunt to match above meter: http://www.kta-ev.com/Deltec_Shunt_500A_50mV_p/mkb-500-50.htm

Toggle switch: http://www.kta-ev.com/Switch_DPDT_Toggle_6_Amp_p/633-m202201-ro.htm

HTH,


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## DavidDymaxion (Dec 1, 2008)

That could be from running too hot. Can you comfortably put your hand on the motor? You could add a blower, like the one in this kit:

http://www.evsource.com/tls_motor_cooling.php

Does the internal fan have its blades? I've heard of cases where the blades get knocked off the fan (an intruding bolt can do that) and that leads to motor overheating.


chronoassassin said:


> Oh God I hope yall can help me out. Back in 2009ish I bought a Evolks conversion kit #2 and installed it in a 74 bug. Its been a struggle since day one. Seems like i can only keep the EV running for about a month at a time then something inevitably goes wrong.
> 
> Today maybe the last straw unless someone can help figure out what i am doing wrong. On my 8mile drive to work the motor stopped working AGAIN, i have had to remove the motor at least 4 times and have it rebuilt cause this keeps happening. Can someone help me figure out why this is a constant issue?
> 
> I dont want to give up on my EV but its getting to the point where its not worth the constant being stranded...


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## GizmoEV (Nov 28, 2009)

I just spoke with D&D to order my replacement motor. While I didn't ask about your motor specifically he did say that the comm bars lifting on my motor were due to heat damage from earlier in its life. You can read my post here: http://www.diyelectriccar.com/forums/showpost.php?p=288777&postcount=14

Basically a normal D&D motor can safely go up to 6000rpm. Mine only went to about 5500 rpm. Given your motor has overheated way more than mine you probably want to keep it below 5000rpm. In any case, this shows that you can shift way later than my might have been. Leave it in a lower gear. As David suggested above, you should really consider forced air cooling. D&D does sell the band which goes around the brush end for $55. That is less than I spent building my own.

Another thing to consider is to go with an 8-brush design if your motor doesn't already have 8 brushes. In any case, you might want to contact D&D and talk to one of their engineers about what you can do. They are in NY so you may have a bit of shipping cost to return your motor for a rebuild but it might be worth it. D&D's website is http://www.ddmotorsystems.com/ but you should just call them. They prefer to talk over the phone and are very helpful.


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## Ziggythewiz (May 16, 2010)

Which D&D motor is it? What speeds are you driving? How long? In what gear?

I have a 144V D&D (ES-31B running at 120) and it will get toasty with just a couple min in 3rd or 4th gear on a 74 bug.


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## chronoassassin (Mar 3, 2012)

Thanx for the help guys, definitely gave me lots of good tips.
I will call D&D and see what their engineers will say, im sure the will just reiterated what yall said.

"Which D&D motor is it? What speeds are you driving? How long? In what gear?"
the motor is the 72v one, cant give more specifics than that currently, I average 30-40 mph for about 20mins. 8 miles to work with lights and stop signs. i take off in 2nd then shift up to 3 then once at 40mph shift to 4th, from what im hearing thats causing problems.


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## Joey (Oct 12, 2007)

Don't give up just yet. I'm afraid that it will be a steep learning curve for me as well to let the car run at higher RPM, once I get my EV on the road. It is counter to what you have learned about driving a car.

I second the idea of a current meter on your motor current. 

Aside from the motor issues, is the balance of your system performing well? I'm just curious, because once you figure out the motor issue, you may have a nice, reliable ride.


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## chronoassassin (Mar 3, 2012)

Aside from the motor issues, I've killed my first set of batteries, but that also seems customary. Also stripped out 2 couplers. So reliability has never been my bug's strong suite.


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## Ziggythewiz (May 16, 2010)

What kind of batteries? I wore out the teeth on my first coupler also, replaced it with a springy type, will see how that one holds up.


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## chronoassassin (Mar 3, 2012)

8v golf cart lead batteries from sams club. 
What is the springy type coupler ?


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## Ziggythewiz (May 16, 2010)

How long did the 8vGCs last? Recently upgraded most of my pack to them.

The springs are supposed to reduce some of the impact on the splines, as with stock.


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## GizmoEV (Nov 28, 2009)

chronoassassin said:


> "Which D&D motor is it? What speeds are you driving? How long? In what gear?"
> the motor is the 72v one, cant give more specifics than that currently, I average 30-40 mph for about 20mins. 8 miles to work with lights and stop signs. i take off in 2nd then shift up to 3 then once at 40mph shift to 4th, from what im hearing thats causing problems.


That is definitely a possibility. If you have some level ground you could calculate the gear ratios by putting it in 1st gear and roll the car for one tire revolution and count the number of turns of the motor. Do the same thing with each gear. You can then calculate the RPM at a given speed from that and the circumference of the tires. If you can't see the end of the motor shaft just remove the snap in cover covering the end of the shaft. If you need help with the calculations just post the numbers here and we can calculate them for you.


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## GizmoEV (Nov 28, 2009)

chronoassassin said:


> What is the springy type coupler ?





Ziggythewiz said:


> The springs are supposed to reduce some of the impact on the splines, as with stock.


The application of torque from an electric motor is nearly instantaneous when compared to an ICE. Sort of like the difference you feel when falling on a concrete floor vs a wooden floor. That constant hammering away when torque is applied pounds away on the drive system. Add to that the shock that comes from road imperfections and you have a recipe for destroying things. Those springs are your friend.


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## Ziggythewiz (May 16, 2010)

GizmoEV said:


> That is definitely a possibility. If you have some level ground you could calculate the gear ratios by putting it in 1st gear and roll the car for one tire revolution and count the number of turns of the motor. Do the same thing with each gear. You can then calculate the RPM at a given speed from that and the circumference of the tires. If you can't see the end of the motor shaft just remove the snap in cover covering the end of the shaft. If you need help with the calculations just post the numbers here and we can calculate them for you.


I don't think there's any issue of him over-reving it, it's likely overheating because of having to run in 3rd or 4th to get decent speeds. VW gear ratios are pretty easy to find.

6000 rpm in each gear would be these speeds:
24.85
46.12
73.34
109.12


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