On the PM brush motors similar to the ETEK, this is a decent read:
My translation:
The ETEK went bye-bye many years ago (before 2009). ETEK's design was based on the Lynch motor design (LEMCO or LMC) and Agni Motors followed. John Fiorenza who had been involved in ETEK motors went and started producing similar motors under the new Mars Electric label which produced the ETEK-R and ETEK-RT motors. Then along the way came the PermPMG (now Heinzmann?) motors which like the motors by Lynch and the Agni motors were axial flux and higher efficiency than the original ETEK. ETEK-R, ETEK-RT (names given by resellers and not MARS) and other perm magnet brush motors we have seen are radial flux motors. Mars later came out with ME0708, ME0709 and other models of axial flux motors.
PMG (earlier Cupex) was to be a supplier for Lynch but instead went off and started making their own high performance axial flux motors (PMG 132) based on the Lynch design. Later, Motenergy seems to have picked up the MARS line of motors and appears to still produce several radial flux brush motors (new and used seen on Ebay and from suppliers like Thunderstruck Motors). Others also have a full line of Motenergy radial flux brushmotor options, e.g. here: - Brushed Motors - MOTORS - EV PARTS (electricmotorsport.com) ($400-800 ish range).
I still see European sources listing Heinzmann PMG132, Agni and Motenergy motor versions as with this site in France: Direct current motors (kit-elec-shop.com) I purchased a set of "ETEK" brushes from them but they turned out to be brushes for a PMG132. Now it looks like they may have the ETEK style brushes so I might have to take a chance on them…would at least keep the boat going for another few years without forcing an upgrade…
In case this helps…
-MT
From: electricboats@groups.io [mailto:electricboats@groups.io] On Behalf Of shredderf16
Sent: Monday, October 31, 2022 1:50 PM
To: electricboats@groups.io
Subject: Re: [electricboats] Elco vs ePropulsion
Miles and F Neil,
Thanks for the info. For the 12 foot dinghy I have a 1.2 kw Hang Kai, which like the Elco is a gas lower end modification. Small prop. I've looked around St Thomas at what people have and there are a ton of inoperative Torqueedos and I do have a friend with an Epropulsion 3.0 which he likes. The Elco is too big for the boat. I consulted with a boat designer friend who's a drag expert and he said it should run at 10 knots on 700 watts. So I'm going to put it in the water and test it with the small motor and see if it's acceptable.
I've noticed that 2 kw and under ebike and gocart motors are getting really cheap on Amazon. If one were to make an outboard leg out of these the most expensive part seems to be the right angle gearbox for the lower end. I found an industrial/farming type that would work but it's not water sealed. Anyone know of one? I agree with Myles that I don't want an underwater motor type unit. What I'd like to do is make a really lightweight leg out of mostly carbon that could swing big props and that is bulletproof. Then use the cheap motors and replace them as needed. It looks like the quality smaller motors like the Etek and Mars have almost disappeared.
I'll write back once I test the boat with the small motor, it might be enough power.
Thanks,
Jerry Barth
On October 31, 2022, at 1:46 PM, Myles Twete <matwete@comcast.net> wrote:
I can't imagine that the drive efficiency loss thru the "90 degree turn from drive shaft to prop" amounts to much. The big loss is in using a small prop.
My outboard conversion has served me well now since converting a 25HP 2-stroke Tohatsu to electric in 2003. There are few with conversions or kits running today that predate this. Thunderstruck Motors had started not long before this and had not yet offered its boat kits yet---I bought my ETEK from them after watching them drag race motorcycles in Oregon in 2003. My telling them about my boat and buying the ETEK from them may have got them interested in targeting the boat market.
Initially, I was not super impressed with the performance of my conversion, yet I was sold. But then initially I was running with the stock 9.9" prop. It did not take long before I modified my lower unit to accommodate up to a 14" prop. I have been running with a 12" diameter 3-blade brass prop for about 18years now and have been quite pleased with the economy. The amount of efficiency gain possible in going to 14" might be worth the expense and hassle, but probably only a small percentage. Still, I may consider that one day.
One thing I will never do: Eliminate the lower unit gearing for some other drive or relocation of the motor to an underwater pod.
I do need to replace my original ETEK 8HP motor very soon. It's served me well for 19 years+ now, but with 3 sets of brushes nearly gone now and none available anywhere these days, I need to upgrade. I'm considering brush and brushless options.
-Myles Twete, Portland, Or.
The Reach of Tide: www.evalbum.com/492
From: electricboats@groups.io [mailto:electricboats@groups.io] On Behalf Of F. Neil
Sent: Monday, October 31, 2022 11:16 AM
To: electricboats@groups.io
Subject: [electricboats] Elco vs ePropulsion
I would recommend checking out the ePropulsion outboards. I first bought an Elco 9.9 and was not happy with the noise and low efficiency. I then bought an ePropulsion Navy 6.0, which is much quieter, and much more efficient with its' larger 3 bladed props. The Elco is basically built on the bottom unit of a small-propped gas outboard, and loses efficiency in the 90 degree turn from the drive shaft to the prop, whereas the ePropulsion is a more modern design, with direct drive motor underwater that the prop is directly attached to. There are lower kW units that would be cheaper than the 6.0 that would be appropriate for your smaller (displacement?) boat.
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