Hot Motor

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nino500
Posts: 63
Joined: Tue Jul 08, 2008 11:24 pm
Location: Isleworth, Middlesex

Postby nino500 » Thu Oct 23, 2008 6:43 pm

Back on the upping voltage score, I would suggest checking in with someone like EVguru on whether the contactor coils etc.will be ok on the higher voltage.

Nino.

Tom Thomson
Posts: 64
Joined: Fri Aug 31, 2007 12:48 am

hot motor

Postby Tom Thomson » Fri Oct 24, 2008 11:42 pm

Thanks for the replies. I don't think I have anything binding or dragging and in any event, that would show as an increase in amp draw. This car, with Nokian tires, will coast for over 1/4 mile from 30 mph. The factory guy returned my call today and thought that perhaps a commutator bar had lifted. He says that the result would be increased heat without increased amps. I hope that is not the case, because he also said that it is not repairable.
My altrax controller will tolerate pack voltage up to about 92 - 93 volts before going into shutdown and my charger puts the pack at 95-96 volts at full charge. This requires me to leave the headlights on for a minute or so before driving away. The low voltage shutdown is supposed to be 60V but mine was never programmed and will function as low as 20V.
tommyt

Nigel P.A. Smith
Posts: 63
Joined: Thu Apr 24, 2008 5:23 pm
Location: Bath

Postby Nigel P.A. Smith » Sat Oct 25, 2008 1:03 pm

Hi Tom,

Maybe if the commutator bars are burnt like Badgers Berlingo commutators, (see pics)

http://www.flickr.com/photos/24533244@N ... 454630810/

they could be resurfaced by a lathe or fine wet or dry paper?

And Nino,

My charger maybe not charging at enough amps; it's an old
Westinghouse C10/96 variable output from 6 to 120 volts, 15 amps but
says not to charge over 10 amps, still charges quite quickly at 7amps
and no floating charge so just turn it off when the Curtis charge indicator
is full.

I was told they should be charged at 28 amps for a 72 volt pack, 3 times
the power and they say the high frequency makes the batteries last 50%
longer? I thought it was a slow trickle charge to make them last longer! :?

Thanks Nigel

Electric Rover
maybe slow but I'm not fuming 8)

Tom Thomson
Posts: 64
Joined: Fri Aug 31, 2007 12:48 am

hot motor

Postby Tom Thomson » Sat Nov 01, 2008 12:52 am

The more I learn the less I know. It has to end. The comm checked ok visually and the motor turned freely. My next step was to get a temp marking pencil with a melting point of 300F. It's soft and crumbly so I taped a chunk to each side of the motor case with duct tape and went for a drive. With gear selection and throttle I held the temp gage at 300 for a few minutes then went under the car. As the temp reading was at the brushes, I didn't expect the case to be hot and it wasn't. In fact, I could hold my hand on the case. I think I'll put the duct tape on the gauge face and press on.
tommyt
ps the motor guy says it is because I'm driving in too high a gear.
correct me if I'm wrong, but if a motor is pulling 100A, what difference
does it make what gear the transmixer is in??????

Tom Thomson
Posts: 64
Joined: Fri Aug 31, 2007 12:48 am

hot motor

Postby Tom Thomson » Sat Nov 01, 2008 11:29 pm

The motor is now at ambient and will be for a while. On the way home from the coffee shop this morn, the controller failed in a most violent manner. The side blew out, coating all nearby bits with black soot and filling the car with vile smoke. It sounds unlikely, but I wonder if the motor heating problem could have been due to a progressive failure of the controller - or perhaps the converse???
tommyt

EVan
Posts: 124
Joined: Tue Apr 10, 2007 8:27 pm
Location: Fife

Re: hot motor

Postby EVan » Tue Nov 18, 2008 9:28 am

Tom Thomson wrote:The motor is now at ambient and will be for a while. On the way home from the coffee shop this morn, the controller failed in a most violent manner. The side blew out, coating all nearby bits with black soot and filling the car with vile smoke. It sounds unlikely, but I wonder if the motor heating problem could have been due to a progressive failure of the controller - or perhaps the converse???


Sorry to hear your controller blew up, we've all been there..

It sounds as though your motor's field wasn't doing much, causing the armature current to be too high. This would tend to stress the brushes and the controller.
The cause could be that the field has shorted through and caused a whole coil or a few turns to be out of circuit.
Anyway you need to check the motor properly before putting in a new controller - get a motor shop to put it on a growler and do an insulation test and so on.

To be honest that motor doesn't really sound big enough for the car anyway.

Nigel P.A. Smith
Posts: 63
Joined: Thu Apr 24, 2008 5:23 pm
Location: Bath

Postby Nigel P.A. Smith » Tue Nov 18, 2008 11:19 am

Hi Tom,

Sorry to here the bad news on the controller, was it the 72 volt Altrax
not having enough volts for the batteries;

"My altrax controller will tolerate pack voltage up to about 92 - 93 volts
before going into shutdown and my charger puts the pack at 95-96 volts
at full charge. This requires me to leave the headlights on for a minute or
so before driving away." Tommyt.

Maybe the shutdown switch was set to high?

This has put me off the idea of adding 1 or 2, of my good but old 6 volt
batteries to the pack to get 84 volts, but I don't want to blow my Curtis
controller, should I wait to get a more powerful controller first?

Sounds like you need a 96-120 volt controller Tom.

Regards Nigel
Electric Rover
Maybe slow but who's fuming 8)

Tom Thomson
Posts: 64
Joined: Fri Aug 31, 2007 12:48 am

Postby Tom Thomson » Thu Nov 20, 2008 11:00 pm

Better news on the Alltrax. Yeah it blew up and no I still don't know why but the factory is sending a new one - no charge! Color me satisfied.
tommyt

User avatar
nino500
Posts: 63
Joined: Tue Jul 08, 2008 11:24 pm
Location: Isleworth, Middlesex

Postby nino500 » Sat Nov 22, 2008 9:30 pm

Just a thought from a non-engineer, but Iwas thinking about the possibilty of a short in the field and the fact that your amps hadn't gone up at the same load seems to rule that out. Obviously, I'd still check everything though.

I was wondering if the brushes might have worn down to the point where the copper wires are embedded and caused more arcing and faster heat transfer through the brush.

Best of luck and let us know the outcome. I have a motor quite similar to yours, which I'm going to try on the 126 (along with several others).

Nino.


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