Here I found more readable chart for the Perm 132 motor (Heinzmann): DC Motor - HEINZMANN GmbH & Co. KG (see "selection diagram"). Looks like it is the right motor for my boat..!
On Thursday, August 11, 2016 6:39 PM, 66b6dcd5b59507e7d751ea81382ea1f6 <no_reply@yahoogroups.com> wrote:
Hi Bendik,
Re efficiency. In the case of my D135 motor http://lynchmotors.co.uk/pdfs/lmc-lem-200.pdf then it can run up to 84V but of course it can run at any voltage up to that and efficiency with more voltage has a bigger spread of efficiency in terms of amps as you suggest, so there are still ratings for 12V, 24V, 36V etc where the right combination of volts and amps can achieve the same peak efficiencies but in a narrower band. So for me and as most sailing boats run at a constant speed it's fine to run a lower voltage. The difference between my 24V direct drive system say compared to 48V geared is say 3% in peak efficiency but then again the 48V needs to have a reduction gear to get the same shaft speed so losses there - which all makes it much the same in terms of efficiency, if not peak and continuous power.
I'm originally a marine engineer Bendik but I may add steam to trade so I'm no electrical or electronics engineer. But yes I've learnt some stuff with DC brushed in the last 5 years and as you suggest have limited knowledge when it comes to other motor types and field weakening etc., where the rpm/volt is not contant at higher speeds.
Yes, to your 400 shaft RPM @ 4.5 Knots prop. I'm 800 at that boat speed.
John R.
Re efficiency. In the case of my D135 motor http://lynchmotors.co.uk/pdfs/lmc-lem-200.pdf then it can run up to 84V but of course it can run at any voltage up to that and efficiency with more voltage has a bigger spread of efficiency in terms of amps as you suggest, so there are still ratings for 12V, 24V, 36V etc where the right combination of volts and amps can achieve the same peak efficiencies but in a narrower band. So for me and as most sailing boats run at a constant speed it's fine to run a lower voltage. The difference between my 24V direct drive system say compared to 48V geared is say 3% in peak efficiency but then again the 48V needs to have a reduction gear to get the same shaft speed so losses there - which all makes it much the same in terms of efficiency, if not peak and continuous power.
I'm originally a marine engineer Bendik but I may add steam to trade so I'm no electrical or electronics engineer. But yes I've learnt some stuff with DC brushed in the last 5 years and as you suggest have limited knowledge when it comes to other motor types and field weakening etc., where the rpm/volt is not contant at higher speeds.
Yes, to your 400 shaft RPM @ 4.5 Knots prop. I'm 800 at that boat speed.
John R.
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Posted by: Bendik Vignes <bendik.vignes@yahoo.com>
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