Is diesel-electric or all-electric the future?

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Originally Posted by Corvidae

Wow, I love seeing the variations in drive set ups. The wiring difference really gets me. Running at 48v I'm pulling 3x the amperage to do the same work. Makes me think your setup runs a lot cooler than mine does too. I'm just starting to see a bunch of stuff get to market at 48v, but now I'm wondering if the higher voltage setups might be the way to go. There's definitely a premium on the inverters/chargers, the lower amp wires are a lot easier to work with, but I don't think the savings really makes up for the premium on the rest of the gear right now. I'm assuming you're using air cooled motors too?

Higher voltage for motors is quite trivial. There are off the shelf motor controllers and motors which can operate at 60V, 72V, 96V and higher. Honestly it isn't much more expensive to make a 30 KW 96V motor as it is to make a 15 KW 48V motor.

The problem is if you motors and motor controllers are running at 72V (or anything higher than 48V) then your primary battery pack will also need to be 72V.

In a marine situation you are likely going to need a AC charger, inverter, solar charge controller, possibly a DC generator, and a DC-DC converter (to get your 12 and/or 24V networks). Finding that at >48V is quite challenging. Even at 48V you will find your options limits compared to 24V or 12V. You can go with a dual battery bank setup (propulsion battery & house battery) but then you lose some of the side benefits of one huge battery bank.

So 48V for driving a 15+ KW motor(s) is very much less than ideal but getting a higher voltage system to play nice with the "marine electrical ecosystem" is even less ideal.

That "could" change someday in the future. Understand the recreational marine electrical market is pretty small and most companies that make marine inverters as an example only do so because they are involved in the much larger off grid market. So if off grid systems ever went from 48V to 60V (or 72V) then you would see 60V and 72V productions from the victrons of the world which would make moving to >48V for the primary pack more viable. As standalone DC systems grow and are used in more power hungry situations that could happen just like the trend towards 48V on high end systems has happened.

Don't get me wrong you certainly could build a 60V or 72V or 96VDC marine propulsion system today it just is a bit of a pain in the ass finding the "everything else electrical" you need. Even stuff as mundane as >48VDC switches designed to operate in a marine environment are rare and expensive.