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Electric outboard drive for small cruisers

  • 17 Apr 2020 02:24
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    Reply # 8904999 on 8896661
    Anonymous member
    I bit the bullet the other day when I found a great deal for 8x 190 Ah aluminium cells for €1180, so will have a 4.5 kWh battery bank. Now I see further reduced the price slightly, those cells would cost €1108 today. Will take a while to arrive from China though (30-60 days from looking at the comments in the reviews).
    On the website it says "Customers should configure a BMS..." What are you going to use? How to decide which BMS is working correctly with these cells?

    electricseas.org is an interesting forum when it comes to electric propulsion on boats. And this appears to be a good read about LiFePo4s on boats: marinehowto - lifepo4 batteries on boats
  • 14 Apr 2020 08:07
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    Reply # 8897465 on 8809939
    Anonymous member

    Now I'm kicking myself for not doing more research into LiFePO4 batteries. I might have spent a great deal less. But I comfort myself with the knowledge that the Relion batteries have a robust inbuilt BMS, and it's difficult to mistreat them.
  • 13 Apr 2020 20:31
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    Reply # 8896661 on 8883295
    Anonymous member
    Anonymous wrote:

    I must say that I think I'm going to actually enjoy this electric outboard, whereas I was tolerating, at best, the petrol outboard. It's quiet, instantly there ready to go when needed without worrying about whether it's not fully warmed up and might stall, and the control when approaching to pick up a mooring is vastly better.

    That's great to hear! Just like I've been envisioning it.

    I bit the bullet the other day when I found a great deal for 8x 190 Ah aluminium cells for €1180, so will have a 4.5 kWh battery bank. Now I see further reduced the price slightly, those cells would cost €1108 today. Will take a while to arrive from China though (30-60 days from looking at the comments in the reviews).
  • 09 Apr 2020 00:20
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    Reply # 8888266 on 8809939
    Anonymous member

    For your use you might consider something like a clear-lidded pelican case for the enclosure.  The model of meter I have has a button on the screen that gives you state of charge info.  I haven't played with it as it's not of much use if you are monitoring an alternator.  But, for your use maybe that might make a useful fuel gauge?  An enclosure with an opening clear lid might allow this kind of function to be retained.

    As I do with most cheap electronics, I took mine apart and gave it a coat of conformal coating.  Maybe that would be good enough if you could mount yours somewhere it wasn't too wet.  The version I have with the button would probably also need a blob of dielectric grease into the momentary switch to extend its life.  
  • 08 Apr 2020 20:56
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    Reply # 8887980 on 8809939
    Anonymous member

    I agree, a Hall Effect ammeter is easier to install than one with a shunt, and seems to be cheaply available if I buy it direct from China.

    If I then install it in an IP67 enclosure, I think it would be fit for purpose.
  • 08 Apr 2020 19:14
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    Reply # 8887793 on 8886814
    Anonymous member
    Anonymous wrote:

    I have the monitor that tells me what the solar panel is putting into the battery, but not what the motor is taking out. To check the power usage as Kurt has done, I should really be putting a 100A ammeter into the circuit, but ideally I'd need a waterproof one in the cockpit.

    I wanted to be able to keep an eye on how hard our alternator was working and bought a hall sensor monitor from Amazon, they can be had even more inexpensively on ebay.  The install is super simple and it reads accurately, as tested with my better quality meters (from memory the voltage was within .1V (display accuracy) and the amperage was within an amp at high currents).  Amazingly it even worked well at low currents, although I'd have to run tests again if you are interested in those numbers.  I was able to extend the distance from the sensor to the display by soldering in some slightly larger gauge wires.  Extending the wires didn't change the accuracy.  I'm sure you could come up with a waterproof cover.  They also sell AC versions of the meter so be careful if you order one.
  • 08 Apr 2020 07:23
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    Reply # 8886814 on 8809939
    Anonymous member

    Even with the Tohatsu in a well, I used to turn it sideways to get off a pontoon against the breeze. There are huge advantages with a steerable motor.

    There are steerable electric pods around, I could have made a very neat installation with one of those, but then I'd be dragging a 10in 3-blade prop in place of the Tohatsu's 7.5in 3-blade prop.

    I have the monitor that tells me what the solar panel is putting into the battery, but not what the motor is taking out. To check the power usage as Kurt has done, I should really be putting a 100A ammeter into the circuit, but ideally I'd need a waterproof one in the cockpit.
  • 07 Apr 2020 23:18
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    Reply # 8884684 on 8809939
    Anonymous member

    Weaverbird breaks free, gets hung on a railway bridge, has no damage, and you get to try out the new electric outboard rather than be stuck at home, and the weather was unseasonably nice.!?   Clearly, somewhere in your broad travels you pleased some sea goddess and she took pity on you.  

    Glad it turned out well.  I think you can add to your list of benefits that for a reasonable price you have a fancy steerable pod like the Volvo IPS, but for a far more reasonable price.  We used to have a little outboard that could be spun and I thought it made docking laughably fun, I bet it is even better with electric.
  • 07 Apr 2020 11:52
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    Reply # 8883295 on 8809939
    Anonymous member

    Another sunny, "warm" day (at least 10˚C, if not more, Eric!), and the situation is back to normal. Yesterday afternoon I fixed the mooring, with a new 20mm nylon riser, a heavy weight halfway up it to keep it below the keels (I usually put a kellet onto the anchor rode, for the same reason, just below keel depth).

    This morning I went aboard, weighed anchor and moved Weaverbird back to the mooring. I must say that I think I'm going to actually enjoy this electric outboard, whereas I was tolerating, at best, the petrol outboard. It's quiet, instantly there ready to go when needed without worrying about whether it's not fully warmed up and might stall, and the control when approaching to pick up a mooring is vastly better.

    I can't recharge the batteries until we're out of lockdown and I can get back to installing the solar panel, so shouldn't do any more trials for the moment, but so far, so very good.
  • 06 Apr 2020 22:33
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    Reply # 8882451 on 8881271
    Anonymous member
    Anonymous wrote:  At least it was sunny and warm.

    Bonsoir

    I have some doubts, under my standards, about the concept of a "sunny and warm" wether in the Highlands in early Appril !

    Well done.

    Eric
       " ...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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