Electric outboard drive for small cruisers

  • 14 Mar 2020 22:07
    Reply # 8827825 on 8809939
    Anonymous member (Administrator)

    I have soldered a few fittings of that size before we went over to using crimping tools. The thing with soldering is that it takes more skills than the crimping tool. Basically, the trick is to first quickly prime the tip of the wire with solder tin (using a torch), and then do the same to the inside of the terminal. Then the wire is fed into the (hot) terminal and finally some more tin through the hole in the terminal is added. It is essential to work fast, or the tin will creep up along the wire without getting good tin saturation inside the terminal.
    Therefore, one has to make a number of trials first to learn it before one moves to the real wires. The correct heat setting of the torch is critical.


  • 14 Mar 2020 20:30
    Reply # 8827672 on 8809939

    £82.29 for a crimping tool?! Phew! There are, indeed, more affordable ones to be found on eBay.

    But I already have a hydraulic press, for sail grommets. I might try a bit of DIY tool-making. It seems to be very simple to rig up something like this, using a V block and a pointed pin.

    Last modified: 14 Mar 2020 20:54 | Anonymous member
  • 14 Mar 2020 19:37
    Reply # 8827588 on 8809939

    I'm probably teaching you to suck eggs, but just in case....  or maybe I'll learn something or someone else might find the discussion interesting.

    I'm not sure what the European standard is, but ABYC recommends a mechanical connection, especially for high current connections.  You can solder as well if you like, but they recommend against solder alone.  The reason is that you can get the connector hot enough in use to melt the solder and then have wires the come loose and short.  Loose ring terminals or a dodgy copy of a genuine connector are two potential sources of heat creating this kind of failure.

    100A is enough current to lead to an interesting situation, especially since it is also part of your backup propulsion system.  Around here many places that will sell you wire will also do crimp for you at little or no cost.  I've used a dimple crimper for large wires for some time, the larger connections all test well mechanically (e.g. 400lb tensile for 4 gauge wire) and I've tested the smaller gauge wires for voltage drop and they also test well above spec.  I don't have a means of electrically testing the larger gauge wires, but mechanical strength is a reasonable proxy (the rafters of my garage groaned when I tested the 00 samples :-).  Given that you live in an area that sensibly uses metric cable and lugs, there are probably many more affordable options for crimpers.

  • 13 Mar 2020 21:02
    Reply # 8826033 on 8809939

    I don't crimp large fittings like this, I solder them, so I think that butt splices, encased in heat shrink, won't be bad for conductivity and strength.

    I find that the supplied connectors are not genuine Anderson, but 120Amp copies branded "Jigo" (an Indian company), so it's not just a matter of buying one connector, I'd have to buy a pair and change the one on the motor as well. I'll stick with the butt splice.

    Last modified: 14 Mar 2020 13:59 | Anonymous member
  • 13 Mar 2020 20:23
    Reply # 8825935 on 8809939

    I'm not a fan of splices if they can be avoided, why not get an extra Anderson connector and avoid the splices (with their additional resistance and potential failure points).  I'm admittedly a wiring weenie, years of designing and flying electric RC planes before it was popular or easy has left me loath to leave any extra electrons lying around.   Check you Anderson connector size, I linked to a 175A connector.  However the only link I found for Haswing and Anderson was for 50A connectors, but that must be for a smaller motor?

  • 13 Mar 2020 19:34
    Reply # 8825870 on 8809939

    As it has turned out when I tried to install the cables today, the cables supplied with the Haswing are just a little bit too short to get as far as the circuit breaker. It seems easiest to use a pair of splices, and since I have to buy more cable, it might as well be 35mm2. If I buy 1 metre each of red and black, and put the splices near the Anderson connector, I can easily get lengths of 1.1 metres instead of the existing 0.8 metre.

  • 12 Mar 2020 23:11
    Reply # 8824275 on 8809939

    My thoughts on solar were formed largely on our 12V system, your 24V system changes things a bit.  However, it is possible to get boost charge controllers so that it isn't necessary to have the panel voltage above the battery voltage.  My thought was that with the location of your panel, shading from the battens/sail is likely to be a problem and could knock out the output from the entire panel.  Two skinny panels parallel to the centre-line, each with a controller, would make it less likely for most of the solar to be lost with shading.  As usual, a set of compromises.

    The oceanvolt looks marvellous, although the price must be shocking.  I was going to go considerably lower tech.  My take on hydro or wind is that they both don't produce much power at low velocity, so you might as well just optimise them for higher velocity.  Low tech hydro would be a towed version similar to a Hamilton Ferris or Ampair.  For coastal cruising it would seem like something like a WattandSea might be more useful in that it would be easier to kick up and put down.  Perhaps an old trolling motor could be made to do the job.  The Haswing wouldn't have the ideal prop, but maybe it would be possible to get power out of it if you were to turn it backwards (to make the prop more efficient).  It probably has three wires running from the brushless motor to the controller.  If you had a way to disconnect those wires from the controller, and connect them to a rectifier, then you just need a charge controller to the batteries (maybe a cheap solar pwm controller).  Make a neat control box and you could have three modes for the motor 1)Power, 2)out of the water for low drag sailing 3)turned backwards and switched for generating when you're sailing in brisk winds.  It ought to be possible to experiment with a cheap second-hand trolling motor before experimenting with the Haswing.  Of course all of that isn't at a necessary for the first season, or maybe ever.

    I'm not sure about the wire calculator you used.  I usually use the Blue Sea systems Chart for sizing wires and they give a different result.  For 100A and a 7.4m round trip (7.6M on the table) run they would recommend 1 gauge for a 3% drop.  It would be easy enough to measure voltage drop during use and then only change things if it annoyed you.  3% would only be three extra amps lost at full throttle and things would be much better at the lower power settings you plan on using most of the time.  It's easy to be a voltage weenie, on the other hand you paid extra for a brushless motor, which is only about 10% more efficient than a brushed one.  Remember you're also likely to have few percent loss due to connections, resistance of the connectors, resistance of the thermal breaker etc.  By the time you get over 5% loss, it might be enough loss of range and max power to consider a wiring upgrade?

  • 12 Mar 2020 22:45
    Reply # 8824239 on 8809939


    I think my main question is answered in the MPPT controller's manual, pp 3/4.

    Magnetic compass? I have one, but I scarcely ever look at it. Soooo 20th century, my dear! GPS gives me a lot more nav info.

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    Last modified: 12 Mar 2020 22:48 | Anonymous member
  • 12 Mar 2020 21:16
    Reply # 8824123 on 8809939

    David, I'm pretty sure the PV panel gives a certain number of amps, the watts is determined by the battery voltage. I'd be confident that a horizontally mounted panel in British waters isn't going to exceed the controller's rating. Some panels have built in by-pass diodes so they can keep working if some cells are in partial shading, you might be lucky. 

    The wire sizings look fine to me, I'm intrigued to see if 30 to 100 amps through a 25sq mm cable circuit does funny things to your compass! 

    Also, when I've worked out how to clone myself to have time for all the projects I'd like to have a go at making a hydro generator, I've built a wind turbine from scratch so have a few ideas to throw at a DIY outboard genny. 

  • 12 Mar 2020 20:08
    Reply # 8823963 on 8809939

    You raise some interesting points, Darren.

    I chose one large panel because that way I get 72 cells and a quoted max power voltage of  38.9V . I can afford to lose some output, and still stay over the 28V I will need to charge the battery. If I'd gone for two smaller panels in parallel, to get the same wattage, I would have less max voltage to eat into. If I'd gone for two smaller panels in series, the voltage would stay up, as I could get up to 72 cells again, so maybe that would be an alternative. Within the space I have available, I could get the maximum wattage with the single panel.

    Then there's the question of how the controller processes up to 38V and up to the panel's max 10A, to put the maximum power at 28V into a 24V battery. What proportion of the nominal 360 watts will the MPPT controller pass on to the battery? 360 watts at 28V means the current would be 12.8A.

    My intention is to see whether the output of the panel limits me in any way, other than having to have enough patience to chill out at anchor waiting for some power to be generated. That would be good for me, to develop a bit more zen. If I genuinely need more power for safety, my preference would be for a wind generator. Having got rid of the drag of a prop in the water, I'm loath to put one back in for hydro-generation. It seems to me that to get good efficiency they need a variable pitch prop, like the Oceanvolt. That way, when there is full boat speed and an excess of wind power in the sails, the hydro power can be turned up to max, but when trying to make headway against a light breeze, the blades can be set to feather.

    With the batteries under the aft end of the cockpit, the weight distribution is very similar to how it was with the Tohatsu, and with that, there was a tendency to go bows down, with water collecting at the forward end of the cockpit. As I carry more ground tackle than normal, for cruising, and as the hull was designed to race with three up, I'm probably a bit light at the stern. I wouldn't want to put the batteries further forward.

    The Haswing comes with 4AWG/25mm2 cables, with a length of about 1.9metres built into the motor, then an Anderson connector, then a further 0.8 metre with ring terminals for the battery connection, in the normal open fishing boat usage. I will put in a 150A circuit breaker at that point, and  then I need a further 1 metre to reach the batteries under the cockpit. That 3.7 metres sounds like a reasonable length to me, for 25mm2 cable, and I'll hold off going up to 35mm2 for the moment. The voltage drop at full power is 2.64% according to this calculator.

       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
                                                               - the Chinese Water Rat

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