Wednesday, January 05, 2022

A few recent thoughts on electric propulsion...

 Well this is scary/interesting, but this ruined my whole day, and something of a palate cleanser in the "Rich men behaving badly" department...

The other day, someone I know was complaining about the high cost of electric propulsion systems for sailboats and it got me thinking.

Since I've had three different electric propulsion systems aboard "So It Goes" I actually understand what what works and what doesn't as well as what stuff actually costs.

Obviously, the real issue, where electric propulsion costs are concerned, is not so much that the various parts are expensive but that the marine trades tend to inflate those costs because it's all about making money.

For my first system I used an Etek motor ($200), a replacement controller for a golf cart  ($100), an aluminum mounting bracket($30) for thirty bucks and an assortment of sprockets and chain for the actual power transmission ($100). The electrical control bits were bought at Radio Shack ($15) and worked just fine. The actual motor mount was cobbled together with some scrap plywood I had on the boat.

Hardly an expensive installation.

As far as the battery bank went I used six-volt golf cart batteries in a 48-volt 200 AH bank.which, admittedly, was far too expensive and heavy in my opinion.

That said, the system worked extremely well once I'd sorted out some overheating issues with the Etek motor. As to the reason why the motor was overheating it was that at extreme low speeds (most of how I actually used the motor) the combination of cooling optimized for high speed use combined with the higher amp loads at lower voltages. The fix was fairly simple and just involved a change in gearing to let the motor run at a higher speed.

The other day I saw a very interesting Chinese EV which costs all of $2000. with lithium batteries included. Now, at $2000 you'd have just about all the bits needful to make an electric propulsion rig for a sailboat. I'd certainly consider buying one of these pickup/dump trucks, taking it apart, and adapting the drive train to turn the prop shaft aboard "So It Goes" for about the same cost of a 6HP outboard or about 10% of what a Marine grade system would cost you...

So maybe we should not be complaining about the high cost of marine EV systems but instead looking at adapting more reality based costing of commercial EV systems that are already out there.

Listening to the Isley Brothers

So it goes...