Update on electric C-Dory

Now that the boat is on its trailer for the winter I wanted to pass on notes to for those interested in converting to electric propulsion.

1. The four 48V 100AH batteries (in two banks) are charged by a 20A charger I placed in the "shelf" in the cockpit. I have found that chargers in a boat need to be at least IP66 rated. The one I have is IP 67. Chargers that have internal fans rather than exterior heat sinks fail within a year because of humidity even if they are in a cabin.

The charger plugs into an exterior grade power supply I wired into the "spare" circuit in the power panel installed under the starboard seat. Since I have two battery banks I plug each one separately into the charger using a 50A Anderson Plug. Wires from the charger to the batteries is 10 gauge. I have posted a photo in my album (WATT NOW) The red power cord is the 120 V line coming in from the shore power in our RV lot.

I have also added solar panels and the charge controllers are in the other shelf on the starboard side. I have two separate panels, one for each battery bank. The panels need to be manually plugged into the controllers so there is no chance of accidentally charging using both solar and shore power at the same time. Photo also added to album. The white box in front holds my Dometic fridge. [/img]

This may have been discussed already, but what speeds are you seeing with those outboards? Very interested in this project as we look for our first C-Dory.

I have two 3kW motors which can easily get me to hull speed. I cruise at about 5.1-5.2 mph using about 2 to 2.1 kW. I posted a graph of my speed vs. power consumption in my album (WATT NOW). Maximum speed is 6.8 mph which uses 5.8 kW of power (my max). Since I have 20 kWh of energy in my batteries my range is about 45 - 50 miles on a charge. The slower I go, the more distance I can travel. Using the equations in Dave Gerr's propeller book I estimate I would need about 11- 12 kW of power to get on a plane.

The electric motors are much, much, more efficient than a gas outboard. Travelling at 5 mph I estimate that I use only 0.4 kWh of energy per mile. Using some of the numbers available on this site I estimate that someone travelling at 5mph using a gas motor would use at 4.0 kWh of energy per mile (assuming a consumption of 8 miles/gallon of gas).

P.S. I see you live in Bellingham. If you are ordering a new C-Dory from NMI (in Bellingham) be sure to tell them you are interested in electric. They were very helpful and I was able to customize my build to accommodate the electric. For example, I was able to get a reduced price since I would not be needing fuel tanks, the hydraulic steering, and the other things needed for outboards. They were able to put in a cable steering at a reduced price. I installed by own throttles and gauges that came with the motors. The only extras I ordered were the shore power connection and the "high top" cabin.

The also helped me install the outboards when I brought them to the factory. There are pictures of this in my album.

Furthering this discussion, I'd like some experiences (preferably) and opinions on options for non-exclusive electric propulsion of my CD22. I purchased a Torqeedo 1103 outboard mainly for use with my large Wenonah canoes (Minnesota II and Seneca) for wilderness trips. It's perfect for this. The incredible efficiency of the canoes lead me to typically move at 100-150 watts, 250 with a stiff off-center bow wind. The 50 watt solar panel can keep up if I only canoe slowly and only a few hours/day and also paddle most of the time.

To use this with my CD22, I put a retractable stern mount on the CD22 where I can mount any reasonable motor up to about 100 lb, including the Torqeedo. For some time, I've had a Minn Kota 80 lb motor on the bow for trolling and holding me in place above a good fishing spot (Spot-Loc). Its a great addition to a CD. The Minn Kota will draw about 700 watts at the highest setting. Practically, it can sustain this for about 5 minutes, then thermally shut off (water currently 50 F). It can sustain about 450 watts, which will push the boat about 3.0 statute mph in ideal conditions. I used it once to get home 7 miles when I stupidly ran out of gas. I now carry extra gas.

The largest draw of the Torqeedo is about 1100 watts, which it can sustain, and which pushes my lightly-loaded CD22 at about 4.3 mph. Running both together I can get about 4.7 mph, which is a nice cruising speed that I'd like to sustain. However, at full thrust, the Torqeedo will last less than an hour. I have a 230 AH 24 V battery for the Minn Kota, so 5520 watt hours and >10 hr for the bow mount. I have 350 watts solar, and can also charge the batteries at 960 watts with a generator. Noise from the Honda 2200 mounted on the stern is not bad with the cabin door closed. That gives significant (essentially unlimited) range for the bow mount motor, but slow. For the Torqeedo, I have two batteries, so about 2 hours or 9.4 miles. Reducing speed GREATLY improves distance. The Torqeedo only charges max 90 watts with the AC charger (I do have a DC to AC converter).

Since I have a 24 volt DC system, I'm thinking about getting a 24 volt electric motor (Torqeedo or equivalent) and another 230 AH 24 volt battery. The Haswing Ventura (2500 watts) looks attractive at $1599, but has mixed reviews. The Torqeedo is 3000 watts ($4298), and claims thrust of 6 HP equivalent. I have two Torqeedo motors, one for nearly 6 years, and both have been great. This claim of thrust is, of course, BS. The Torqeedo 1103 claims 3 HP equivalent, which is also BS. My Cruise-n-carry 2.7 HP 2-cycle outperforms it, but is stinky and godawful loud. I'll carry it for emergencies, but I'm looking for quiet cruising and no fuel messing-around-with for 4 hr and maybe 20 miles/day. If I add another 460 AH battery and buy a Torqeedo Cruise 3.0 (3000 watts), will that likely move me near 5 mph? Tom's post of the Gerst equation shows I'd need about 3000 watts for 5 mph. Thus, 20 miles would be 12000 WH, and I can renew that overnight at dock or running the generator. I might also add solar panels to 500 watts. My experiments so far have been with a relatively lightly-loaded CD22, and for long cruises I'll want to load to maybe 5000 lb. Instead of the 5 mph, I might be able to accept 4.5 mph.

Any ideas on options? Is any of this realistic for sustained trips? Of course, I do have and will often use the Honda 100 hp motor on the stern. Its very quiet at low speed. Currently, I often find myself motoring at 5 mph because I like to look at everything. I want time to react and to reduce the implication of an impact, as there are often things bigger than my CD22 that can do major damage at high speed floating in our coastal PNW waters.

Thx for posting about the Torqeedo. I’ve thought about getting one for slow cruising. I love how the battery is integrated with the motor, so no cables dangling/tangling and no need to mount a separate battery somewhere.

You state the following:

“For the Torqeedo, I have two batteries, so about 2 hours or 9.4 miles. Reducing speed GREATLY improves distance.”

So, is it fair to translate this as 2 hours at approx 4.5 mph?

Roamad said:

Thx for posting about the Torqeedo. I’ve thought about getting one for slow cruising. I love how the battery is integrated with the motor, so no cables dangling/tangling and no need to mount a separate battery somewhere.

You state the following:

“For the Torqeedo, I have two batteries, so about 2 hours or 9.4 miles. Reducing speed GREATLY improves distance.”

So, is it fair to translate this as 2 hours at approx 4.5 mph?

Click to expand...

Not quite. I was getting 4.3 statute mph with the Torqeedo only, not 4.5, and this with lightly loaded and no wind/tide. The batteries I have are 915 watt hours, so 50 minutes each at 1100 watts (full throttle). Two batteries would be 50+50 = 100 minutes or a little less than two hours. A clear option for a few miles. Several hours...no.

The Torqeedo is ideal for a tender. You can put the motor on first, and then the batter, rather than having to put the whole thing on. Easier as we get older. Thataway already touted this advantage, and it is a very substantial one for me at 69 years old.

Thx for clarifying. I think a Torqeedo would work for some of the short trips we make, like to the fuel dock a couple miles upriver or nearby swimming spots.

You are really limited with the Toqueedo. Any wind or current shoots the "mileage" to bits, of course depending on which way the wind is blowing or current. I owned a Torqueedo 1103 for about 12 years--it was an excellent dinghy motor and I highly recommend it for that use. As for pushing the various C Dorys and other boat: I did use it as an emergency get home a couple of miles when fishing along 7 mile bridge and the boat being at Knight's Key at Marathon--a few miles away. For the much lighter and easier to push thru the water Caracal Cat. For the C Dory 22 and 25 when Loaded, I considered the practical speed at 3 mph to have any range. On a Dingy I ony pushed its range when we had an emergency on Lake Powell and I had to go about 15 miles and at times try and head off a ranger's boat to direct him to where the medical emergency was. It passed that test. But look at the Australian experience with solar panels etc--they did push an inflatable about 30 miles in the ocean, with large solar panels, but...the speed was low and amount to drive a smaller and lighter inflatable uses much less power.

I consider the best "compromise for a "kicker" / get home / dinghy motor to be the Suzuki 2.5 hp 4 stroke, which weighs in at 30#, about the weight of the fully assembled Torqeedo. The Torqueedo does have the major advantage of light weight parts, none more than about 12 lbs. The Suzuki is much cheaper, and uses very little fuel. A gallon will take you a long way. The Suzuki 2.5 is about equivilant or slightly better for pushing the boat. In reality (as noted) the 1103 is really not equal to a 3 hp outboard in pushing power--closer to 2 hp. But it does work and work well for dinghies or easily driven boats short distances.

The Suzuki 2.5 is as low as $770 on line (probably plus tax and shipping). The Torqeedo is $2,799.98 at West Marine locally, and the second battery is another $1000 dollars. So: close to $3000 vs close to $900. Plus the outboard has range only limited by the amount of fuel you have available for it. If I had to take a C Dory 22 from my house to Cancun Mexico, it could be done with a 2 1/2 HP probably close to 800 miles on the gulf of Mexico plus a 20 miles in the Straits of San Antonio. Suzuki- maybe 20 miles with the if very slow, winds and currents in our favor.... sure that is a radical idea---but it sets the tone.

If you want all electric, go the way Tom has. It will serve you much better.

The hand drawn graph in my album (WATT NOW) has the electric power requirements at different speeds for my 22' cruiser. This summer I have confirmed that the graph is accurate, but I have not yet posted the new graph I have developed. [the excel graph is for my previous St. Pierre dory] You can use the graph to estimate what different outboards and trolling motors will give you in terms of speed. 500 W will get you about 3 mph and 1000 W about 4 mph. I cruise at 2000 - 2200 watts and average about 5.1 mph. Always use the actual watts manufacturers claim rather than hp equivalent. The Torqeedo especially is noted for very high hp equivalents.

As noted in the discussions above, one of the big issues is the capacity of the batteries. Volts x Amp hours will give you the maximum capacity of your battery. For example a 12V 100AH battery holds 1200 watt hours (1.2kWh) of energy. At a consumption of 1000 W this battery will last at most 1 hr. For lead acid batteries that is actually only about 1/2 hr because they should not taken down below about 50% of their capacity.

I have used trolling motors as my primary propulsion in my two previous e-boats and they do overheat and shut down on prolonged use at higher power. I overcame that problem by drilling holes in the throttle head and mounting small computer fans to force air across the controller. This was for the MinnKota 36V 112. The Motor Guide motors have the controller down in the motor housing and cannot be cooled except by going into colder water.

Electric vs gas is up to you. Each options has its good and bad points. It all depends on your needs. As you can imagine, I am all in favor of electric and have learned to live with its down sides.

So, I'm narrowing it down. I want to cruise electrically at about 5 statute mph for hours per day, and hopefully recharge partially with solar (600 watts), alternator (30 amps = 360 watts) or generator (Honda 2200). Occasionally 110 volt charger at dock. Tom has two EPropulsion Navy 3.0, which are great except they require 48 volts, and my system is and will continue to be 24 volts. EPropulsion is thus out. I have and will add another 24 volt, 230 AH (5500 WH) battery for a total of 11,000 WH. I could series the batteries to 48 volts, and then possibly even go to a 6000 watt kicker (EPropulsion or Torqeedo), but can't charge 48 volts from my solar, alternator, or generator on the fly. I'd have to reconfigure the two 24 volt batteries to parallel for charging and reconfigure to series for motoring, not impossible, but not desirable. Thus, I've narrowed it down to two possibilities for the rear kicker with enough umph to get me to near 5 statute MPH and charge on the fly...the Torqeedo Cruise 3.0 (3000 watts) or the Haswing Ventura (2500 watts). I'll get the remote versions and hook to my main for auto-steering. I've had great luck with my two Torqeedo motors over greater than 6 years. Torqeedo's customer service was great in replacing a faulty battery and charger. I use these motors a lot for my Hobie and for canoes. The main thing is price. The Torqeedo is nearly 3x the price of the Haswing. I could also consider two Haswings for a max 5000 watts and keep at 24 volts. I also like redundancy in case of a motor failure. I see almost no user experience with either motor I'm considering, and none except Tom's happiness with the EPropulsion on his own. Has anyone used a Haswing product, and, in particular, does anybody know anyone that has used a Haswing Ventura? Also, advice of experience with either Torqeedo or Haswing in general will be appreciated. Thanks in advance. Rob & Marcia

Rob, given that you have a 24 v system I would still recommend you go with a 48V motor. 2000 watts at 24 volts requires a current of 83 amps which is quite a lot in my view. That would require large wire sizes depending on the total distance between the batteries the motor and back. To charge a 48 V battery from a 24 V system I would suggest getting a "boost" charger that will raise the charging voltage. There are a number of different products available; just google 24-48 v boost charger. I also have a boost charger for my solar panels since they only produce a maximum of 20 V. If you go with a 48 V motor you will have a wider choice of options that will get you the 2000 W you need.

Rob, I took a look at the Haswing ventura on line and noted a few potential problems with it. It is listed as a trolling motor and as such I don't think it is designed for long term cruising. If the actual controller is in the throttle head I did not see any options for cooling, and I have found when using the 36 V MinnKotas that they overheat and I had to add cooling and fans. If the controller is in the motor (like the Motor Guide) I also had problems with cooling under continuous use when I was near the maximum current (especially in warmer waters). For continuous use I had to throttle the trolling motors to less than half their rated capacity (in amps). All of these motors have thermal shutdowns without warning, and that was a bit frightening the first few time it happened. The Epropulsion motors have an internal fan in the head.

On another topic: I would not recommend that you cruise at wattages that are near the maximum of your motor. I like to have a little extra to push against the wind. A 10-15 mph head wind raises my power consumption to 2400W to maintain 5mph. AND, it takes 5800 watts to get up to 6.8 mph when I need to move faster to get out the way of the ferries here in Puget Sound.

Agreed, there are significant advantages to 48 VDC. Problem is, I already have much of my system at 24 VDC, including my beloved Minn Kota bow mount 80 lb motor, and my Renogy DC/DC charger that combines solar with the alternator and also charges the starting motor with solar. I'm going to think a lot about setting up two 24 VDC batteries in series for the kicker, and how that might be handled with the hardware I already have. That would also let me get the Navy 6.0 as the motor to bring me to 5 mph, which it should do handily. I will, of course, have the Honda 100 there in case of strong headwinds, tides, etc. I already do a lot of slow cruising with it, and it is nice to get 9-10 mpg at hull speed instead of 4-5 mpg on step. Thanks for the good advice.

I also looked at the Haswing review--one trolling motor got more 1 star reviews than 5 star! That is a new low. No way would I even consider a product like that.

The 600 watt solar, will turn out to probably produce 300 to 400 watts reasonably average reliably--and that is assuming no cloud cover or fog/haze/smoke etc. It might be good at Lake Powell, but in the PNW and similar areas, it will be compromised. Then the loss converting to 48 volts.....Not much Ooomph there...

Tom is correct that you are going to be stressed to get 5 mph. I would go with the Navy 6.0 without hesitation. That will cost about the same as the Cruise 3 Torqeedo. But you will have to significantly up your battery power. Another battery will be close to $1,000 and will give you another 2000 Watt hours usable--so you will have about 4000 usable watt hours at 48 volts.. Yes they theoretically can give you 5500 watt hours each, but realistically you want to not discharge them more than 80%. That is a lot to recharge. You will probably want a larger 110 V marine battery Charger. I had 50 amps for two 100 amp hr 12V Li--so you are probably going to want at least 25 amps if you are going to stick with 48 volts. The Victron Skylla 25 amp 48 volt charger is about $900. That or Mastervolt are going to be best for marine chargers. (there are work arounds with 24 volts..but I would go with 48).

Also now you have two unmatched LI batteries--and they should be balanced. Not sure how you would handle this....(Perhaps Li Time has real engineers on staff. I know that BattleBorn does, and when I wanted to add a battery to my Li bank, they wanted the history and had me test it, so the battery they shipped would be closely balanced to the existing battery). Li batteries with this much power are not really "plug and Play".

I am trying to put some realism into this. You need a place near the motor for those batteries: Maybe you can stack them between the fuel tanks? Each battery is about 10" high, and there needs to be space around for cooling. Where is the existing battery? Also each battery weight is about 80 lbs, so you are adding amost another 160 lbs in the stern.

If you are looking to use the electric for longer distance cruising, I would start from scratch to put a system together rather than cobble something together that would require all sorts of compromises. First I would suggest a separate battery pack for the motor. In my experience trying to mix and match batteries, different chargers, and different power drains is a recipe for problems. It's all the different switches that you have to remember to turn on and off in the right sequence.

My suggestion would be to go with the Navy 6.0 and two Bestgo 48 V 100AH batteries (https://www.electriccarpartscompany.com/48v-100ah-preferred-lifepo4-lithium-battery-pack ) for 10kWh of energy, or something like this. These will fit in the space of one of the fuel tanks on either side of the transom. Their weight is about that of the full fuel tank they replace. That will still leave you with one fuel tank for your outboard. You can see the batteries below the transom in the picture. I have four batteries. One thing I have found when using lithium batteries for long distance cruising is that you need some way to monitor the voltage in each cell. These Bestgo has a waterproof rating of IP66 as well as a bluetooth connection to your phone that provides readings for each cell. I have found that the cell balancing system of all batteries I have researched uses a balancing current of 1000 mA or less. After 4 or 5 years of steady use, that balancing current used by the BMS is no longer high enough to bring all cells to a full charge. At the beginning of the season I fully charge the battery and check to see if any cell is below the spec. If so, I use a desk top power source to "top off", with the voltage set at the maximum for that battery and the charging current at or below the balancing current in the BMS. Using this approach I now have a 20 kWh LiFePO4 bank in my RV that is 13 years old and still going strong.

you need some way to monitor the voltage in each cell

Click to expand...

Do you cut into the battery case to measure the individual cells? Or is there a buss bar or similar where you can check the voltage of each cell? (There are going to be 16 cells in a 48V battery, with both series and parallel connections between those many cells to give the 48 volts and large capacity.)

The resting fully charged voltage of each indivual cell will be 3.40 volts. The 100% charged, resting voltage of a "48 volt" battery will be used in 54.4 volts. I believe it takes 16 individual cells to make the "48 volt" battery. Or does your blue tooth monitor give voltage for each cell. In either case, how do you access the individual cell to charge and balance it?

The first use of LiFePO4 battery in an RV, that I know of, was over 20 years ago, and each year the company who was supplying the batteries, would tear down the case of this custom made battery to be able to access each cell and then charge and baance them to a fully functional battery after building a new case around the individual cells.

The higher end LiFePO4 batteries today have a blue tooth connection to your phone or tablet that show the individual voltage of each cell so you don't have to open the box. You can even monitor them while in use to see if any one cell has a larger voltage sag than the others. The picture below shows what it looks like for a 36V battery. I don't have a picture of mine, but it looks similar. Each one of my 4 batteries will show up on my phone separately and all I need to do is toggle from one to the other.

I built my original battery bank using individual 180AH cells and wired a volt meter to each one separately (second picture). I also added a plug to each cell so I could charge it individually (plugs at the left side of the picture) before I discovered I can use a desk top power supply. In the old days (10-15 years ago) one had to build a battery bank from scratch and add your own BMS. In my previous post, yesterday, I discuss how I balanced the cells using a desk top power supply so I don't have to open up the case at all. The third picture is an example of the type of power supply I use. Since my new batteries are only 2 years old I have not had to rebalance them manually yet.