My summer project was to convert our auxiliary outboard power from a Tohatsu 6HP 4 stroke XL outboard to a Hangkai 7HP Electric outboard. During August 2023 I started a Facebook discussion on electric propulsion. All the comments were about how well a trolling motor works on a smaller boat but few on larger sailboats. Here is what I can tell you so far about switching to electric propulsion. Good:
- No gas or ethanol smell.
- Low noise.
- No pull string.
- Reliable, instant power.
- Few development problems (except battery failure).
- You can easily carry on a conversation while the outboard is running.
Bad:
- When your battery runs out you are dead in the water (D.I.W.)
- Hangkai is VERY Chinese and all that it imparts as far as questionable quality.
- No North America support or parts. Walmart Online Vendor Joy Buy Express is horrible support.
- Minor problems besides cheap workmanship.
- No strain relief on accelerator cable.
- No means for a dead man switch/cable.
- Voltage display lens started melting in one hour of sun exposure.
- Poor documentation. Quote from page 4: "Prohibit use in rain". Because it is leaky?
 Specifications:
- Motor -
- Hangkai 7HP Electric.
- Probably closer to 5.5HP.
- 48 Volt.
- 1800 Watt.
- Cost $350 US (2023), Walmart on-line.
- Battery - (Not included).
- Four SLA 12V, 18W wired in series. (Similar to 'KM' brand Part #ES17-12).
- Wired with #10 marine wire.
- Weight ~60 pounds.
- Batteries in a Group 27 box, (Grainger item# 49EJ90).
- For a "proof of concept" I acquired 10 batteries from a robotics team via a generous $ donation.
If they ever wear out I will replace them from Amazon; currently ~$160/4.
- Battery Charger -
- Beleeb Mdl:BLB-C20.
- Charges battery in a half hour on 'Low' setting.
Conclusion:
- Motor works well in light wind.
- It easily pushes the SJ23 for thirty minutes at 4 MPH (2/3 power) on one battery pack. More than enough to get me in and out of the marina.
- Top speed is ~5.5 MPH with no wind, compared to a Tohatsu ~6.1 MPH.
- For pushing an SJ23 in a marina it works just fine.
- For transiting an SJ23 over extended distance or punching into head winds, use a gas powered outboard.
Planned:
- A static pull test; (similar to engine dyno rest).
- A timed test run of the battery.
- Modify Tech Tip to mount Battery 'A'.
- Remove water tank for battery charger.
Dan Lewis
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