After considerable experience with electric propulsion on the 18m proa I conclude that regeneration offers very little benefit.
Any sort of modern electric motor with electronic controller will have a regenerative mode as most are designed for regenerative braking in traction applications.
The fundamental problem is the physical limitations of the motor. If you have an electric motor that will push the HP to say 6 knots it will risk flying to pieces if left in the water at 15kts. You also need to ensure the motor is happy to run backwards at speed as well when left in the water. In light to moderate wind, an electric motor just turning in the water will be a significant portion of the overall drag. Inevitably there is a narrow window of operation where you would bother to use the regeneration.
The significant secondary problem is range anxiety with any pure battery propulsion system. Regenerative charging is not of any use when your battery is flat and you want to make way through a channel in dead calm. In fact solar panels are not much help either as you need to allow for the worst case charging, which can be close to zero for an entire day and the collected power may be just enough to keep the nav lights running and the GPS alive.
The 18m proa has progressed from a small portable petrol generator that enabled charging a single battery at 500W; to a 26HP Chinese made air-cooled diesel that was coupled to one DC generator driving both thrusters in a series circuit to now a 52HP water cooled diesel driving two DC generators directly connected to their respective thruster. The air-cooled diesel was a tad under powered and very noisy at any speed. The batteries are still used for tight manoeuvring as they enable completely independent operation of each thruster.
Over the years that the electric thrusters have been used on the 18m proa, the regeneration has only been used a few brief times to confirm it works.
Someone told me that cruising sailing boats spend on average 60% of the time with their motor running. In my limited cruising experience I was always reluctant to start the motor. My motoring threshold was if going backwards. Most cruisers inevitably succumb to some sort of schedule even if it is to beat an adverse weather system or catch a favourable current.
Rick W
On 22 Jul 2019, at 10:50 pm, '.' eruttan@yahoo.com [harryproa] <harryproa@yahoogroups.com.au> wrote:Given Robs tender motor reuse for boat motoring, I was wondering if an electric tender made sense, as the tender should not need a long power duration.
Then I was wondering if dragging the prop might be a redundant/additional power source. Given swapping the prop out for one optimized for 'dragging', does this idea have any merit?
__._,_.___
Posted by: Rick Willoughby <rickwill@bigpond.net.au>
| Reply via web post | • | Reply to sender | • | Reply to group | • | Start a new topic | • | Messages in this topic (4) |
SPONSORED LINKS
.