From their graph, regen (regardless of the 3 props they tried) generated about:
· Near zero regen until 5kts
· About 160watts/knt speed increase above 5kt
So unless you're at 5.5kts or more, you're basically not going to get usable regen.
Doubtful that you can do much better than that without going to larger props…I'd guess that changing from a very efficient permanent magnet brush motor to a brushless won't get you much improvement if any. Most of the good ones of each type these days are up in the same efficiency range. Increase prop diameter and now you're talking improvement.
And there's the rub: Folks will ask if regen is worth it, but the devil is in the details. If you can swing a big, slow prop, AND IF you expect to be sailing or anchored in good current, sure, it could be worth it. Most folks can't justify it.
I once put up my 400watt Air403 wind generator while heading upstream on the Columbia River. We had a good 12knot following wind blowing. The beauty of this was that the boat got a small amount of upstream push from the wind generator's wind drag while at the same time generating about 50 watts of power. And there's the rub there: I'd never see 400watts from that wind generator unless I saw 2x that wind speed (ie 24kts) to get 8x the power (400w). And it's a rare day that I'd be out motoring with a 24kt wind. So I don't bring the Air403 wind generator along anymore---one 50watt solar panel can give the boat as much free power as 12kts of wind.
Anyway…
From: electricboats@yahoogroups.com [mailto:electricboats@yahoogroups.com] On Behalf Of 66b6dcd5b59507e7d751ea81382ea1f6
Sent: Thursday, May 25, 2017 12:28 AM
To: electricboats@yahoogroups.com
Subject: [Electric Boats] Re: Would using a BLDC/PMAC motor and controller as a generator be a good idea?
The regen video I posted earlier is a hybrid
https://youtu.be/5Yo4_mB9u4c
and it is from Graeme Hawksley of Hybrid Marine.
As you'll see in the page here he's using a brushed Lynch motor:
http://www.hybrid-marine.co.uk/5.html
Having said that if you go to the home page they are now using brushless.
On the Lynch you can alter the brush timing by rotating the brush plate to optimise output, much as you would on an old car with points.
Somewhere I have the tests of a Lynch acting as a generator. If I find it I'll post.
John R
Posted by: "Myles Twete" <matwete@comcast.net>
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