Re: (ET) Replace a lift strap, motor, etc....

["David Roden" <etpost drmm net>]

If the motor smells funny, and it's not a hot oil smell, you're probably 
cooking the varnish on the windings.  

I run my lift motor at 24v, and I think that's as high as I'd want to go 
on 
a motor designed for 12v.  

I'm  not an engineer, but as I understand it, at nominal voltages a well-
designed series motor's natural back EMF will help to regulate the current 
it draws at speed.  

I think you're right that for a given power output, double the voltage 
SHOULD mean half the current.  But that doesn't mean that you should just 
double the voltage, because the power oiutput WON'T stay constant.

When you increase the voltage, you increase the available power output at 
all speeds.  I think this is not just because of Ohm's law, but also 
because 
it bucks more of the current-limiting back EMF.  Again, my understanding 
from EV work (subject to revision by true engineers) is that the main 
danger 
is at high load, low speed, and therefore high current.  However, at high 
speed you can also fireball the brushes with too much voltage.  So getting 
carried away with the overvoltage thing is a hazard all round.

Be a bummer to have your lift let its smoke out in the middle of moving 
18" 
of snow, eh?


David Roden - Akron, Ohio, USA

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