Differences between AX2500 and AX3500

We have been using Roboteq motor controller for over 2 years now. Our original application used the AX2500 with no problems. The current requirements for our application rarely exceed 40-45 amps, so we moved to the AX3500 early this year.
Here are a couple of undocumented differences (as far as I know) between the controllers:
- Grounding. The AX2500 has a separate ground for the motors and the power in to the controller electronics. This allows the vehicle to have the motors are a separate 'dirty' power system and the controlling electronics do not have the deal with the noisy ground place created by the motors. The AX3500 has these grounds tied together.

-Over voltage Protection. Our system is a 36VDC system. When the system is charging is has voltage of around 42 VDC. While charging the system, we sometimes run tests that involve running the motors with no load. This caused no problems with the AX2500 in the last 2 years. The AX3500 can not take the voltage. We actually smoked 3 AX3500 controllers trying to figure out what the problem was. Now we never run the vehicle during charging and everything is OK.

Hope this helps someone.

<P style="MARGIN: 0px">The AX3500 and 2500 are absolutely identical on the two points you mention:
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<P style="MARGIN: 0px">- All ground pins or wires are connected to the same point.
<P style="MARGIN: 0px">- Overvoltage threshold and protection is the same.
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<P style="MARGIN: 0px">It is not clear why the 3500 would be more likely to fail but we will carefully analyse damaged units for futher clues.