Boat Generators

[huale]

Hi to all, Just want to say I’m really not interested in AC generators on boats. The problem is AC generators must maintain a constant speed to produce the required frequency and, since the generator must be sized to meet the peak power load plus margin, most AC generators operate seriously under loaded the majority of the time. This under-loaded condition shortens engine life and makes a lot of unnecessary noise.

I’ve tried to eliminate AC power loads and used inverters to power many AC loads but air conditioning systems remain a significant exception.

My proposed solution is a diesel engine driving a variable displacement hydraulic pump and a hydraulic motor driving an AC generator. The variable displacement pump allows the engine speed to be independent of the generator speed, so engine RPM can vary with loading. A speed controlled hydraulic motor will maintain the AC generator at the required 3600 RPM (60 RPS) and a hydraulic accumulator will dampen out power surges. An additional benefit is that the hydraulic system can directly power other boat systems such as the anchor windlass and davit lifts which typically require very high DC http://www.kynix.com/Detail/669784/DC.html currents.

By making the generator engine and hydraulic pump slightly larger and attaching a hydraulic motor/pump to the main shaft, the generator can double as an auxiliary drive to provide a get home capability and the main engine can power the hydraulics. This eliminates the requirement to run the generator while underway in order to air condition the cabin.

Since the typical battery charger is only 25 amps, using an AC generator to recharge a large battery bank is a very slow process, which contributes to extended periods of generator operation at low loads. To reduce the recharge time, I plan to have a high output alternator such as the Balmar 98-24-220-BL http://www.balmar.net/98dimensions.htm which will produce 200 amps at 3600 RPM and shortens the bulk charge time by a factor of 8. If you wanted to shorten the recharge time further and/or provide an online spare, you could add a second alternator and combine them with the Balmar “Centerfielder” http://www.balmar.net/PDF/Centerfielder.pdf .
Thanks all guys.
Regards;
huale

[JoeM]

Interesting information. Sounds like a fairly complicated system best used for larger craft. I am intrigued by the ability to use the generator engine for emergency propulsion.

But, and I apologize for my ignorance, isn't that too much load to put into a battery system? Don't you need to throttle the load like the computer controlled chargers with Bulk charge, Float charge, etc? And, At a certain point aren't more Amps unnecessary eventually ruining the battery?

Or is this setup mainly for A/C loads and NOT battery charging? If so, that is still a lot of amps in my opinion.

[huale]

Interesting information. Sounds like a fairly complicated system best used for larger craft. I am intrigued by the ability to use the generator engine for emergency propulsion.

But, and I apologize for my ignorance, isn't that too much load to put into a battery system? Don't you need to throttle the load like the computer controlled chargers with Bulk charge, Float charge, etc? And, At a certain point aren't more Amps unnecessary eventually ruining the battery?

Or is this setup mainly for A/C loads and NOT battery charging? If so, that is still a lot of amps in my opinion.

I'm not sure, but thank you reply to me.

[JiminTex]

Have you considered a diesel 1800rpm generator? There are quite a few out there. You should never exceed 80% of rated power, to allow surge of motors and compressors. Info on selecting a generator.

https://betamarinepnw.com/selecting-the ... -generator

https://www.northern-lights.com/

Electric Marine Motors

https://www.elcomotoryachts.com/electric-101.shtml

[JiminTex]

Also check out http://fischerpanda.com/