Thanks for the link. The torqueedo web page is indeed much more informative than that of other trolling motor sources.BMI wrote:Minn-Kota and similar trolling motors have a very low overall efficiency of less than 20%.
Torqeedo motors have a much higher efficiency of around 50%. A Torqeedo motor will provide double the run time/range per charge compared to if you were using a Minn-Kota or similar trolling motor.
You might want to check the efficiency curves and technical info on the Torqeedo website here-
I hope that helps!
When a regular Minn Kota Endurance 30 can be had for $99 at Walmart.Price slaps ya in the face at around $1800 US.
After some thought, I'll probably go with something inexpensive first to see how much actual use I can get from it. I already have plenty of NiCd batteries from the eBike hobby, so I only need a trolling motor lower end. I can buy a new inexpensive Minn Kota, or buy a used one, and harvest the lower end. Then drive with either the Minn Kota controller, or an eBike controller.gilnet wrote:not sure to what degree of excellence you're looking for.
An integrated rudder/motor like this is pretty much exactly what I had in mind making.GGoodrum wrote:Hobie is now offering a Torqeedo-based option for their kayaks. It is a slick setup that comes with two mounts, one in place of the rudder and the other replaces the pedal drive up front.
Of course not everyone can afford the performance and efficiency of more than 50% efficiency delivered at the prop for the Torqeedo motor compared to the overall efficiency of the Minn Kota at barely 10%.jag wrote:An integrated rudder/motor like this is pretty much exactly what I had in mind making.GGoodrum wrote:Hobie is now offering a Torqeedo-based option for their kayaks. It is a slick setup that comes with two mounts, one in place of the rudder and the other replaces the pedal drive up front.
It is nice there is a commercially made version, but no way I'm paying 2k. More likely I'll take the lower end of a $100 trolling motor (like this Minn Kota Endura 30) and graft it to the rudder mechanism:
No doubt the Torqeedo has superior engineering design, and will perform better in general. It may not always be a 5:1 ratio advantage though. This graph is provided by Torqeedo and would seem to show that the Torqeedo is vastly superior to in particular the low power "competitor". However, it fails to mention anything about how it was measured. If it was an actual test on a boat that boat may have been to large for the smaller of the competitors.BMI wrote: Of course not everyone can afford the performance and efficiency of more than 50% efficiency delivered at the prop for the Torqeedo motor compared to the overall efficiency of the Minn Kota at barely 10%.
chvidgov.bc.ca wrote:http://www.lightperformanceworks.com/lp ... ystem.html
The linked site has an off the shelf relatively inexpensive kayak trolling motor which is premade to work with existing rudders...
I'll be curious to hear about your work jag, as I have a Greenland II folbot as well..
Wouldn't it be better to replace the Minn Kota controller with a 48V brushed motor controller and trim the throttle signal to restrict the output to 12V max? Feeding a PWM 12V Minn Kota controller with PWM power from the 48V to 12V golf cart converter seems unwise and a bit inefficient. 48V brushed controllers may be cheaper than the converter.chvidgov.bc.ca wrote:I'm building a sailing canoe these days, and I've just aquired a Minnekota PWM 40thrust ("EnduraMax") for backup propulsion on calm days and for salmon trolling. I'm going to try running it on two of my 48V Lithium ebike batteries using a DC DC 48 to 12V converter for golf carts, which is supposedly rated for 30Amp output. I doubt continuous. I hope it will work, if I don't max the motor out for long at a time. The runtime should be AWESOME compared to AGM, not to mention the much reduced weight. At first, I thought I would build a big 12V headway battery, but figured the efficiency loss of the convertor might be ok given the advantage that I could use my existing packs etc.,possibly even pulling the boat to the water with my bike.
I'll admit that I may be in over my head on the technical aspects, but I'm fairly sure that a DC 48V to DC 12V converter is a buck converter. Buck converters use PWM to achieve the voltage conversion and have an induction coil to smooth out the output voltage ripple. If your buck converter doesn't smooth out the voltage ripple well enough, it may output 'dirty power', or a harmonic, that doesn't play nice with the Minn Kota PWM controller.chvidgov.bc.ca wrote:I'm not sure what you mean when you say the converter is PWM. It just produces plain old DC 12V at a max of 30 amps, with 90% efficiency, and provides it to the EnduraMax PWM controller. The power isn't PWMed by anything other than the Minnekota controller. If I limit my end wattage to 250w using just the throttle alone it should be straightforward I think. 20Ahr of 48V lithium should be equivalent to maybe 150Ahr of lead acid AGM given the Peukert effect on the lead which would probably only put out 80 amphrs. I should be able to run that motor for days at only 5 amps coming from the lithium which is only .25C, which is transformed to 20 amps at 12 v out of the converter - my canoe should be able to do 3 knots at that wattage which is my target top speed. Its a displacement hull and will only do 5 knots max anyway, so it would take a stupendous amperage to get it over 4.5 knots. I hate to take apart a brand new motor like that - and I'm more excited by the sail rig anyway which will be awesome - just need to sort my leeboard/ex-snowboard I might put a different prop on the motor too, later. See how it goes. I imagine your idea would work as well - either way I need to be careful not to suck too many amps with my throttle setting, as I understand it.