Quote:
Originally Posted by jackman08
Im finding it hard to believe that a higher amp controller will not increase speed. After installing a 400 amp alltrax; I think my speed increased greatly. If I had to guess, and thats what it would be, a guess, I would say at least 5 mph, and I would really think more. Is this just my imagination?
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If it was a SepEx Drive (DCS or PDS), there was a speed increase. This is probably due to different field mapping for the DCS. For the PDS, in addition to different field mapping, the 4200RPM limit imposed on the motor by the stock controller is eliminated and a stock PDS motor will spin at about 5600RPM at 36V.
Replacing a stock 300A PDS controller with an Alltrax DCX300, which is also a 300A controller, will up the top speed from 18MPG to 24MPH on 18" tires at 36V. However, replacing the stock PDS controller with a DCX400, or DCX500 or a DCX600 will also up the top speed to 24MPH on 18" tires at 36V.
If it was a Series Drive system, a top speed increase of 5MPH was probably due to other things replaced at the same time the controller was replaced. For example the voltage drop across the contacts of a used stock (85A) solenoid is greater than the voltage drop across the contacts of a new 200A solenoid. Same is true if with a new F/R switch and high current cables.
I'm not sure if it would produce a 5MPH speed gain, but higher ampacity controllers drop less voltage per 100A of current flow. For example an AXE4834 (300A series controller) drops about 0.30V per 100A while an AXE4855 (500A series controller) only drops about 0.09V per 100A. However at max RPM, the motor is most likely going to be drawing less than 100A, so the output voltage difference is very small. Unfortunately, I don't know what the voltage drop per 100A is for stock controllers, but it would have to be pretty high to get much of a speed gain by reducing it.