Over the weekend I finalized the system installation and yesterday we had the first sea trial. The boat is a 1975 Dufour 34, about 14,000#. The system’s main components are: Mars ME0709 (Etek RT), Kelly PM72401 controller, QuickCharge multi-battery charger, 72V AGM battery pack, 400A solenoid, and Paktrkr monitor. Gear is 2.4:1 ratio, high-torque synchronous. The system started immediately. The only problem was the AMP meter, which unfortunately did not work.
Conditions: wind was somewhat gusty, 10 knots, flat seas. The boat has been in the water for a long time and there are quite a few barnacles on the bottom, and I would guess on the propeller too (unfortunately the Northern Chesapeake is getting murkier and it is very difficult to visually check more than 1 or 2 inches deep). The prop is the same, inefficient two-blade 13x10 that was used with the diesel.
First impressions: unbelievably quite. Up to 3.0/3.2 knots it was impossible to tell if the motor was running or not, at 4.0 a low hum, a little louder at 4.5 (the engine compartment is sound insulated and the motor/gear frame is mounted on the old diesel mounts). The difference between motoring with and against the wind was less than ½ knot at around 3.0 knots. We took the boat against the wind up to around 5.5 knots (which it would have been the limit with the diesel, given the hull/propeller condition) and I still had about ¼ of the throttle run left. After a minute or so we lowered the speed to 3.0 knots and I checked the system, the controller was not even warm (it is mounted on a hefty heat sink), the motor was quite hot to the touch. I would have liked to be able to read the amp-meter… Besides the quite ride, the other great surprise was backing into the slip: for the first time I had good control and immediate response. Once on shore power, the battery charger got really hot (more than the motor), to the point that I will relocate it to a better ventilated area.
Overall we were extremely happy. Range with the smallish 105Ah bank will be the next item to determine, but I expect it to serve us well for the kind of sailing we do.
For those using the ME0709, how hot does it normally get?
Alberto
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