Electric outboard drive for small cruisers

  • 17 Apr 2020 10:26
    Reply # 8905396 on 8809939

    Nice initiative David!

    Horst, I haven't decided on a specific BMS yet but in important thing to look out for (if it applies to your cruising ground) is that it has a low temperature cut-off (usually configured around 5 deg C) as LiFePO4 cells are damaged if charged below freezing. You can test if it works by putting the temperature sensor in ice cold water and measure whether the charging stops.

    An alternative to low-temp cutoff on the BMS would be to have it on the charge controller instead, if solar is your only power source. For example Victron sells separate temperature sensors that you can hook up to their products. That said I think it's more sensible to have it on the BMS level so that you're protected whatever charging method you use.

    And it's obviously worth being skeptic about super cheap products. There are a lot of good independent reviews of solar equipment (battery cells, BMS's, solar panels etc) on Will Prowse's channel. Electricseas.org as you mention is a good resource as well, many interesting project threads to read through, and the article you linked to seems like a good read, thanks!

    I'll try to post here when I figure out what I'm going to buy and why. So far, in addition to the cells, I've also ordered a 24V to 12V converter.

    Last modified: 17 Apr 2020 10:27 | Anonymous member
  • 17 Apr 2020 07:29
    Reply # 8905230 on 8809939

    I've edited the heading for this topic from "Electric drive for Weaverbird" to "Electric outboard drive for small cruisers", so that Oscar and anyone else who is adding outboard electric propulsion to boats in the 18 - 23ft range can post here, on their own work, and we can keep all the info we gather in one place.

  • 17 Apr 2020 02:24
    Reply # 8904999 on 8896661
    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
    Reply # 8897465 on 8809939

    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
    Reply # 8896661 on 8883295
    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
    Reply # 8888266 on 8809939

    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
    Reply # 8887980 on 8809939

    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
    Reply # 8887793 on 8886814
    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
    Reply # 8886814 on 8809939

    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
    Reply # 8884684 on 8809939

    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.

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

                                                              Site contents © the Junk Rig Association and/or individual authors

Powered by Wild Apricot Membership Software