Electric motor

Welcome to PocketShip.net! This bulletin board is for builders of the Chesapeake Light Craft-John C. Harris "PocketShip" design, a 15-foot micro cruiser sailboat built from a kit or plans.

For more information on PocketShip, click here: http://www.clcboats.com/pocketship

This site gathers PocketShip builders in one place. Here you can share photos, tips, questions, and---eventually---your sailing adventures in PocketShip! CLC will also post design updates and tips here as they come up.

We'll try to knock down spam as quickly as possible.

Moderator: John C. Harris

Forum rules
Spam or commercial posts will be deleted.
This is a civil forum: no flames or drunken tirades.
Please stay on-topic.
PocketShip's Web Page: http://www.clcboats.com/pocketship
If you need CLC customer service: http://www.clcboats.com/forms/contact_us.html
We'll try to delete spam as soon as it appears.

Re: Electric motor

Postby Wayne G on Wed Sep 07, 2016 5:43 pm

Thanks Captain Charlie. Very helpful.

Wayne
Wayne Gray
Orlando Florida
Wayne G
 
Posts: 88
Joined: Thu Jul 14, 2016 11:19 am

Re: Electric motor

Postby DanaDCole on Mon Jul 03, 2017 7:30 am

In my original post I was not informed enough about the difference between thrust and horsepower. Understand it a bit better now.

FYI, I finally decided to purchase the Torqeedo Travel 503. It saved me a little money ($1,700) and is more than adequate for the job. It is rated at 1.5 HP and while it doesn't move me along quite as briskly as the Yamaha 2.5, it does a very good job--and I'm not in a huge hurry to maneuver around docks! Some folks might be happier with the 3 HP 1003, only about $300 more.

I like the way it starts up almost instantaneously (nice in an emergency situation) and "shifting" to reverse is merely a matter of twisting the throttle the other way.
I have ordered a cable that allows me to charge the battery while on the boat, so I'll never "run out of gas." (Except maybe at night!) Not sure how 12 volts can charge a 30-volt battery, but obviously they have it worked out--the AC charger only puts out 12 volts. Maybe they figured out a way to charge only a few cells at a time. Don't know, I wrote and asked for clarification but maybe it is a secret.
DanaDCole
 
Posts: 497
Joined: Wed Sep 25, 2013 2:06 pm
Location: Stillwater, Oklahoma

Re: Electric motor

Postby riverron on Tue Jul 04, 2017 7:38 pm

Glad to hear the Torqeedo is working out for you. I am seriously considering getting one. They even have a newer model/battery out that supposedly lasts a lot longer. It is more expensive though. One thing that is pushing me towards it besides not having to deal with gas and fumes, is that it would be easier for my wife to use in case something were to happen to me on the water.
riverron
 
Posts: 256
Joined: Fri Aug 07, 2015 10:29 am
Location: Richmond Virginia

Re: Electric motor

Postby DanaDCole on Tue Jul 04, 2017 11:34 pm

I purchased a cable that allows you to charge the Torqeedo battery via a 12V "cigarette lighter" socket on your boat. I haven't been able to experiment with it yet except for a brief test to be sure it works, but it seems to me it should be able to get your battery charged or mostly charged back up while you are not using the motor. If that works out I see no need for the much more expensive Torqeedo high capacity battery.

I'm pretty sure most everyone has a solar panel on their boat, so that means you are totally moving the boat with either sun or wind power. Love it! So all you need (if you don't have one already) is a relatively cheap solar panel to keep your main battery charged. No need to buy their very expensive solar charger. The cable was about $35 from Defender. Or Torqeedo sells one for $50 or so, but it is no different electrically.

I was surprised that a 30-volt battery can be charged with a 12-volt charger but they have it figured out and it works. in fact, the AC powered charger that comes with the unit puts out 12 volts. I guess they have figured out a way to charge groups of cells individually. They are not saying--proprietary I guess.
DanaDCole
 
Posts: 497
Joined: Wed Sep 25, 2013 2:06 pm
Location: Stillwater, Oklahoma

Re: Electric motor

Postby TassiePete on Wed Jul 05, 2017 5:23 am

Charging a 30V battery with from a 12V supply is nothing special, so called DC-to-DC Step-up Converters have been around for a long time. I have a couple of concerns about charging the motor battery from your house battery. The regular 110/240V charging unit charges the battery (about 300Wh) with 3A (or 4A) and it takes 8+ hours to do so. A trickle charger cable, as the name implies, will take a lot longer. Even if it were to charge at the same rate of 3A, you probably will need a solar panel rated at 80-100W, which is rather large, and it will need a charge controller. A 100W solar panel on the boat will rarely be oriented optimally, will be shaded by the sail at times, the sun will not always shine, etc. So the real output of a 100W panel is probably about 40W on average over time (and not necessarily over 8+ hours), which is what you need to have 300Wh available (12V x 3A x 9 hours -> 324Wh). Remember that you will need the 40W+ to supply 3A at 12V (36W). The difference are losses in the charger (chargers usually get a bit warm). On a rainy day, the solar output is zilch, so you will drain your house battery quite a bit.
Either way, sunny or not, if you are ever in trouble and run your motor battery down, you have no options left. To get 15 minutes of motoring time back, you will need to charge for 2 hours, or a lot more with the trickle charger cable ... wind and waves might carry you a long way during that time and in a direction you may not want to travel.
TassiePete
 
Posts: 69
Joined: Tue May 02, 2017 4:31 am
Location: Port Huon, Tasmania ( Down Under )

Re: Electric motor

Postby DanaDCole on Wed Jul 05, 2017 7:53 am

Thanks for the info. I was unaware of the step-up converters. I use about 10% of my battery getting out of the launch area. The solar panel charges a 95 AH battery so the DC cable shouldn't use much of it to re-charge the Torqeedo battery. You point out that it is a trickle-charger though, so if that is correct it may take more than the hour or two of sailing that I usually do to get it back to 100%, although that is not really necessary.

Anyway, I'll do some testing when I have time and let you know how it works out. Another option, if the DC cable does not work is to use an inverter to run the AC-powered charger, but there is some loss of efficiency there, so that may be a better or a worse "solution." But worth a shot.

This is not really a problem because after leaving and returning to the launch site I still have 80% left (12 or so miles, according to the digital readout, and depending greatly upon throttle setting). I just like to have a little extra insurance in case of an emergency so that is why I am experimenting.

I'll keep everyone updated.
DanaDCole
 
Posts: 497
Joined: Wed Sep 25, 2013 2:06 pm
Location: Stillwater, Oklahoma

Re: Electric motor

Postby TassiePete on Wed Jul 05, 2017 4:22 pm

I looked at electric propulsion as well, and I guess it all depends on the application. We will be sailing in salty "protected" waters and on the coast - in both cases mostly rocky coast line, few settlements and quickly changing weather. I decided to go for a petrol engine, just for the ability to go for 6+ hours if I have to. My electrical system will be the simplest possible: a 45h battery with a charging socket accessible from the outside, LED nav and LED anchor light and a little cabin light. All up less than 10W, realistically less then 50Wh / night, even if under way at night. Handheld radio with spare battery, torch, and the iPhone for occasional nav/speed checks. A 12V power socket allows for the radio or the phone to be re-charged if needed.
I would be interested how much the trickle charge actually delivers. It is easy enough to measure with a little multi-meter.
TassiePete
 
Posts: 69
Joined: Tue May 02, 2017 4:31 am
Location: Port Huon, Tasmania ( Down Under )

Re: Electric motor

Postby DanaDCole on Wed Jul 05, 2017 5:18 pm

I don't blame you for wanting more range if needed where you will be sailing. Your electrical system sounds similar to mine. I have more battery capacity because I was originally thinking of using it to power a trolling motor . I 'll let you know the charge rate after l do some teasting. Probably next week.
DanaDCole
 
Posts: 497
Joined: Wed Sep 25, 2013 2:06 pm
Location: Stillwater, Oklahoma

Re: Electric motor

Postby DanaDCole on Mon Jul 10, 2017 11:04 am

The Lehr propane comes with either long or short shaft. I also have the mount Captain Charlie recommends and I second his recommendation.
DanaDCole
 
Posts: 497
Joined: Wed Sep 25, 2013 2:06 pm
Location: Stillwater, Oklahoma

Re: Electric motor

Postby DanaDCole on Mon Jul 10, 2017 11:16 am

The Torqeedo is a great success so far. The skeg does drag in the water on a port tack if you are heeled quite a bit, so I recommend the short shaft (not being sure, I purchased the long shaft version just to be on the safe side). Some might wish the 3 HP version for a little more "zip," but I find the 1.5 HP to be more than adequate.

In some locations I may use as much as 5 - 10% of the battery capacity but if I sail for an hour or so I find that my on-board power has back up to 100%. I have a 95 AH battery and it will have dropped around 3 - 5%, but the solar panel has it back to full charge in a few hours (even though the sail is usually shadowing at least a third of the panel.

So this system works very nicely. But if you don't have on-board power, you should be in good shape. Even if you have to move the boat quite a bit to get to a place to start sailing, you should find after returning to port that you still have at least 60 - 70% left. "Quite a bit" is a vague term--I'd guess you could move the boat a half-mile to a mile or more each way and still have plenty of battery left. There is a new battery with much higher capacity, but I don't think it is worth the expense if all you are going to do is maneuver in and out of marinas and so on.
DanaDCole
 
Posts: 497
Joined: Wed Sep 25, 2013 2:06 pm
Location: Stillwater, Oklahoma

Previous

Return to PocketShip Forum

Who is online

Users browsing this forum: No registered users and 15 guests

cron