Planning for an electric engine conversion

One of the dreams of mine is to replace the diesel engine with an electric one. Electric engines are amazing and provide far more torque at low speed, are a lot more reliable and are quiet/non-polluting.

There is one big problem though – batteries still suck. Even the most efficient electric engine can only run for around 3-4 hours at 80% hull speed on a load of six batteries. The solution is either to load up on even MORE batteries or find some other way around.

Now, my idea is with a combination of large solar panels (such as ) mounted above the cockpit (with a custom bimini frame) and 1 or 2 wind gens is to have about 1500/2000 watts of renewable standalone electricity generation.

Elco Motor EP-2000 is the engine I am looking at (AC motor) or the AC20 (72Volt)

For batteries, it’ll have to be lithium or AGMs if possible (which are literally 1/5 of the price).

I think the runtime of both engines is calculated on 220AH of batteries at 72volts, or 1320AH at 12v. In Watts this is 15840. This bank would take around 10-20 hours (allowing in a large fudge factor) to fully charge from depleted to full using (obviously, not how I am going to run them). The runtime of the first engine at hull speed on 220AH of batteries is around 3 hours at 80% hull speed, going up to 6 hours at 60%. If the battery bank takes 5-10 hours to charge up halfway then in theory I should be able to run for most of a day.

Another question I have is for the house bank – would I be able to link it up to the charging as well without damaging the batteries? I heard going above 1000 watts on 12 volts is a pretty big no-no. What would be the best way to link the engine bank and the house bank? Would running them off the same large bank be ok (I am guessing no). These are all questions I don’t have the answer too yet, but it’s exciting to see that this stuff is theoretically possible!

One step I can take in the meantime is to see if I can get hold of a replacement element for my water heater that runs on 12 volts – that way I avoid the ~15% power loss that would hit me if I went through an inverter.


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