RE: (ET) chargers

["David Roden (Akron OH USA)" <roden ald net>]

On 1 May 2002 at 16:53, SolidTech wrote:

> So, to use this type of controller what happens
> to the field weakening - just not used?

This looks like a Curtis of some type.  It's most likely designed for 
series golf 
car motors.  

I've thought about trying one of these on the ET, but hesitated.  The 
reason is 
that series motor controllers count on having a fair bit of inductance in 
the 
motor (thanks to the series field), and I'm not at all sure that the ET 
motors 
have enough. 

What happens of there's not enough motor inductance?  A couple things, I 
think (I'm not an engineer, I'm going on a somewhat hazy understanding 
here, 
so someone should correct any misstatements I make).

First, Curtis controllers seem to start very jerkily when there's not 
enough 
motor inductance.  It's like starting in maybe speed 2.  To me, having 
smooth 
low-speed control is the big advantage of a transistor controller, so if 
that's 
missing, I'm not very interested.

Second, I think that if the inductance is too low, the current limit 
doesn't work 
right.  This can cause the MOSFETs to commit hari-kari (burn out) if you 
overload the motor.

I'd say "proceed with caution," and let us know how it goes.  

BTW, if you miss this one, no sweat. I'm pretty sure these guys have been 
selling these controllers for quite a while (the name sounds familiar).  
You 
can also get rebuilt Curtis golf car controllers for a little more, 
generally for 
around $175-220 or so, from Golf Tech Industries : 

     http://www.golftechind.com/

David Roden
Akron OH USA