Electric outboard drive for small cruisers

  • 24 Mar 2020 13:44
    Reply # 8853569 on 8809939

    Do I understand correctly: with those CALB cells you don't even need to solder to make a battery yourself? Soldering (which I just don't seem to master) is the main problem I've been afraid of so far, when thinking of a DIY lithium battery.

    To keep the budget down, one could make a 100Ah 24V battery first, and add another one later - right?

  • 24 Mar 2020 13:04
    Reply # 8853495 on 8809939


    Excellent tips regarding the charge controllers, thank you!


    The cheapest option (apart from buying second-hand cells, which would be a viable option) I've found would be CALB cells. Example:


    With these 12V/100Ah would be about €400 (€800 for 24V/100Ah, €1.6k for 200Ah).

    In addition you'll need a BMS, which will set you back between €30-200 depending on type/features. If you aren't planning on sailing in freezing temperatures you don't need low temperature cutoff and a Daly would work fine, although it would be a good insurance to have it anyways (if you forget to unplug chargers when wintering).

    So for 24V/200Ah €1800 would be in the ballpark.

    If buying used cells (90% capacity) it could probably be closer to €1000 although I haven't looked into this extensively. Another cheaper option that some go for is to buy a used electric car battery pack. The problem with this is that they are mostly lithium-ion, which can be a fire hazard, so LiFePo4 is the way to go. LiFePo4 also has better discharge rate and is non-toxic.

    Another option (probably better but slightly more expensive) would be to get 200Ah cells.

    As for LiFePo4 in general I really don't see any practical reason* for anyone to use lead acid batteries for anything anymore, so I would've switched even without converting to electric motor. When you factor in usable amp-hours and overall life expectancy, LiFePo4 is actually less expensive and a far superior battery technology.

    *) except short-term financial

    PSA: You can find a lot of good information, reviews and tests in Will Prowse's Youtube channel.

    Last modified: 24 Mar 2020 13:04 | Anonymous member
  • 23 Mar 2020 17:22
    Reply # 8849999 on 8809939

    But now that lockdown seems imminent, and Scotland doesn't want visitors overloading its infrastructure, the project has to be considered as being on hold. It doesn't seem sensible to proceed with installing the solar panel. If I am spared, there might be a short cruise to be had in the Autumn, but nothing before then.

  • 23 Mar 2020 17:18
    Reply # 8849992 on 8809939

    Yes, I was thinking of something of the sort. The magnetic key comes with a lanyard and a clip which will attach to the pushpit, but I was thinking of an additional Velcro band or perhaps just duct tape, though it would be good to be able to remove the key easily to prevent unauthorised use.

  • 23 Mar 2020 15:13
    Reply # 8849687 on 8809939

    I wonder if it might be worth gluing the kill switch in place?  I've never known anyone to use the kill switch as designed on a sailboat as large as Weaverbird.  However, I have experienced pulling the outboard start cord multiple times (longer than I care to admit) to no effect because the kill switch was not in place.  Also, with a standard red-outboard-button-kill-switch, should the "key" for the switch go over board or get lost, you can substitute anything that would lift the button of the kill switch.  With a magnetic kill switch it might be hard to find something on board to substitute.  In a dinghy a kill switch makes sense, but I think it might create more of a hazard on a larger boat. 

    Congrats on an other step towards freeing yourself of infernal combustion.

  • 19 Mar 2020 16:47
    Reply # 8842512 on 8809939

    Yesterday, I took delivery of the hydraulic crimper, cables and terminals, and had no trouble in making up the lengthened leads I needed.

    This afternoon, I installed them. Then I hit a problem. Or thought I had. I was getting a long "beep" from the motor. There are high voltage, low voltage and high current warnings and cut-offs, but these make a short or fast-short "beep". The manual is badly translated from Chinese, and under "long beep", it just says "Motor stop operation, wait the throttle back to neutral position".

    Then I had a lightbulb moment. I hadn't put the magnetic kill switch in place. This is not mentioned anywhere in the trouble shooting section.

    I put it in place. Problem solved. The prop now whizzes round. It's quite noisy for an electric drive (out of the water), but nowhere near as noisy as a petrol outboard, of course. I think I'll be reassured if I can hear it going, and how fast. If it were completely silent, that might be too little information.

  • 19 Mar 2020 06:55
    Reply # 8841472 on 8809939

    Looking at the pictures of the Caroute N300, I would say that the motor housing, prop and transom mount are identical to those on the Protruar 5.0 and only the controller and tiller on top of the shaft look a little different - my guess is that the components are being made by a factory somewhere in China, and then various companies are building them into a consumer product for retail sale.

  • 19 Mar 2020 04:54
    Reply # 8841398 on 8840627
    Anonymous wrote:

    As for panels I'm looking at 3-400W as well (can't reasonably fit much more on a small boat) but I might want to split it over two panels to minimize issues with shading. For charge controller I think I'm going with the Victron MPPT 100/20. Not sure from where I'll buy these yet, gonna shop around for good deals when it's time to pull the trigger (soon, once I get home to Finland).

    Oscar, around here the Victron charge controller pricing pretty much scales by amperage, so it is worth considering getting several smaller controllers rather than one large one.  The MPPT works better when it is only optimising for a single panel, you get better resilience to shading, and you have built in redundancy in that you only lose a fraction of your solar should a panel or charge controller fail.  Thus, depending on what panels you use it might be worth considering the Victron 75/10 or 75/15's.
  • 18 Mar 2020 22:09
    Reply # 8840760 on 8809939


    have you got.a price estimate on a diy 24V 200Ah battery?

    (And good luck getting back here during this mess, hopefully you can make it.)

  • 18 Mar 2020 20:59
    Reply # 8840627 on 8809939
    Interesting, Oscar! You're going for the Haswing Protruar 5.0 too? Is your source for the solar panel and controller the same as mine?

    I wasn't aware of the Haswing at all but it looks like a solid choice, so yes, probably. :) Haven't really crystallized my plans in terms of brands/models/vendors just yet. I had been looking at a Caroute N300 (which was what initially triggered the idea of using an electric outboard) and it's quite similar in specs - 24V, 160 lbs thrust, 2.5kW. Managed to get as far as finding an Ebay seller that ships to Finland, but the Haswing actually seems like a much better choice since it's a) considerably cheaper and it's b) from an established brand so there would be a lot less hassle with warranty and parts (if needed).

    As for panels I'm looking at 3-400W as well (can't reasonably fit much more on a small boat) but I might want to split it over two panels to minimize issues with shading. For charge controller I think I'm going with the Victron MPPT 100/20. Not sure from where I'll buy these yet, gonna shop around for good deals when it's time to pull the trigger (soon, once I get home to Finland).

       " ...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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