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Old 03-25-2008, 10:53 AM   #7 (permalink)
Ford Escort 2.0
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Join Date: Feb 2008
Location: Alameda, CA
Posts: 240

Electricar - '89 Ford Escort LX Hatchback
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I have a 48v system and an Alltrax 4844 controller, and a series DC motor. You also have a series motor - two of the posts are for the armature (A1 and A2 connect to the brushes) and the other two (S1 and S2) are for the field.

This will increase the top speed of a series motor, essentially when the Alltrax (or whatever type of controller / contactor you have) is at full, stable power. In other words, your accelerator is hammered down. If you have top speed issues (such as you can't get more than 50 MPH with ForkenSwift) then adding a field weakening setup could give you another 5 MPH or so.

It may not seem like much, but the extra 3 or 4 MPH I get is a big difference.

You can do a quick and dirty test by using a jumper cable (one of the thin, cheap ones - #6 wire) to jumper S1 and S2. The cables will have enough resistance to weaken the field somewhat without a regular resistor (some people just use cable as the resistor). Probably best to have a passenger connect the cables while you drive the car. If it has an effect, it will increase speed slowly (over a few seconds) but noticeably.
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