Hi Brian,
I've seen that rating info from Motenergy, but I think that it has a big assumption built in. For rating purposes, Motenergy states that the max continuous current for the ME0913 is 125A AC into the motor or 180A DC into the controller, as you stated, But which controller? I assume whatever Motenergy sells. But if these numbers are correct and the AC figure is RMS, that controller is losing over 2600W at that setting (less than 70% efficient?), which points to a serious cooling problem for that controller.
However, I think that most of us are now using Sevcon Gen4s with these motors for marine installations. I know that my Gen4 barely gets warm to the touch when run at 50A and running at 100A did not produce any significant heat at the controller. I know that the same motor using the older Millipak controller needed a big heat sink on the controller and there were still occasional controller heat problems. But my Gen4 is mounted flat on a wood bulkhead (no air gap) and I have never had any heat issues. The controller temp has been such a non-issue that I haven't bothered logging the displayed controller temp when doing performance testing. Given this data, one can deduce that the Gen4 is much more efficient than earlier AC motor controllers. I can only say that my offhand observations concerning DC current going into the Gen4 controller versus the AC current coming out of the controller, observed using a Sevcon ClearView display, show that the DC and AC amps are pretty close indicating pretty high efficiency. This is supported by the observed low controller temps while in use.
So in practice, at full throttle in open water (6kts in my 30' 10,200# ketch), I pull 106A from the batteries. If I remember correctly, the displayed AC current is close to 100A. Full throttle tied to the dock (0kts in my 30' 10,200# ketch) increases the load and my drive has pulled close to 140A from the batteries in those conditions, though only for a few minutes because I started the experiment with a mostly depleted battery pack. Controller and motor temps were still reasonable, Of course this is a worst case scenario, with my presently installed motor, reduction, and prop, the boat just can't pull that sort of current while moving. I guess that I owe the group a high load run tied to the dock for 30-45 minutes or more to see how the controller and motor behave, including DC current, AC current, controller temp, and motor temp. Maybe I'll get around to it this summer. If so, I'll publish the results here.
Fair winds and smooth seas,
Eric
Marina del Rey, CA
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