Tuesday, May 1, 2012

Re: [Electric Boats] Re: new system from scratch, am i on the right track please?

 

there are no DC generators beyond a commutated machine, ie mechanical rectification.
An ac machine avoids a mechanical component thus usually increasing reliability.
Rather than diodes synchronous rectification offers higher efficiency.
 
...  How beautiful it is to do nothing, then rest afterwards
    

From: Steve Dolan <sdolan@scannersllc.com>
To: "electricboats@yahoogroups.com" <electricboats@yahoogroups.com>
Sent: Tuesday, May 1, 2012 3:44 AM
Subject: RE: [Electric Boats] Re: new system from scratch, am i on the right track please?

 


Jules,
Without the basics it's hard to deturmine what you need but as far as in general here's my input

> it seems better to use a diesel generator to produce DC with a large enough capacity to power the electric drive motor(s) directly for the times when i need cruising speed.
> this will let me get away from the "usual" AC output genset that has to be converted to DC before being sent to the motor controllers(s).

Direct DC is preferred; it eliminates inverters to DC and simplifies the system. I have a AC genset and would much prefer a DC for simplicity however it really depends on the size of the system and whether the cost is justified for the more expensive DC genset. My genset has a manual variable output to manage the charging of the batteries. Something I have to pay attention to, the new gensets have an automatic start/stop which I'm a little leery of.

> add a battery bank of the same DC voltage as the generators output and the motor controllers input.

Correct.

> add a single phase battery charger for shore power top up.

I'm not sure why you would want to go to single phase, a 240V will give you more amperage, a quicker charge and smaller wires. Depending on the battery type you also want a multistage charger.

> add a 230 VAC output inverter to run the onboard appliances.

Correct. I'm assuming this is a European boat. 120v for US system.

> if i can get my hot water from the genset that about finishes the system?

A genset with a heat exchanger is what I have and works great. I also have a 10 gal. HWH for the storage and heating during shore hookup.

> if i am heading in the right direction, i will bore you with the boat details, but i thought i would get the theory right before moving on to the practice.

Also plan on several switches so that you can't operate the genset and shore power at the same time as well as the inverter only when operating the genset.

> thanking everyone in advance

Hope it helped.

Steve in Solomons MD
Lagoon 410 SE


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