Trolling Motor to Battery Bank? - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > General Interest > General Discussion (sailing related)
 Not a Member? 


Reply
 
LinkBack Thread Tools
  #1  
Old 06-14-2012
snider's Avatar
Senior Member
 
Join Date: Jun 2006
Location: Charleston, SC
Posts: 284
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 9
snider is on a distinguished road
Trolling Motor to Battery Bank?

I just bought my wife a 1979 Com-Pac 16. The boat didn't come with a motor so I'm going to get a trolling motor for her. I don't know a thing about boat electrical sysyems. The previous owner just rewired the boat using two 12V wheelchair batteries. It's a pretty basic system. The batteries go to a solar charge controller, then to the panel. There is a spare spot on the panel. Should I hook up the trolling motor there? Also will the two wheelchair batteries be enough to run a 45lb thrust motor for 1 hour?

It's a neat set-up, but there isn't much draw on the system. It has a voltage monitor, charge controller, led cabin lights, running lights, am/fm radio and a spot for a vhf.

Also the charge controller and voltage monitor stay on all the time. There is a solar panel for recharging. Right now the boat is under the carport while I rebuild the trailer. I'm worried about completely discharging the batteries. Should I just unhook the batteries, or install a cutoff switch? I'll add a picture or two later. Thanks
__________________
Brandon
Charleston SC
Starwind 223 & Compac 16
Reply With Quote Quick reply to this message Share with Facebook
  #2  
Old 06-16-2012
snider's Avatar
Senior Member
 
Join Date: Jun 2006
Location: Charleston, SC
Posts: 284
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 9
snider is on a distinguished road
Re: Trolling Motor to Battery Bank?

I've been doing some research and do far I've decided on one of two options. Get a stand alone trolling motor battery and connect it to the solar panel via a combiner. This way both banks can charge via the solar panel bit remain electrically isolated for use. The other option is that when I find the trolling motor I want I'm going to calculate my total electrical usage. If I have enough now I'll just run the motor from the panel, otherwise add batteries to bring the bank up to what I need.
__________________
Brandon
Charleston SC
Starwind 223 & Compac 16
Reply With Quote Quick reply to this message Share with Facebook
  #3  
Old 06-17-2012
Senior Member
 
Join Date: Jul 2011
Posts: 130
Thanks: 0
Thanked 1 Time in 1 Post
Rep Power: 4
Allen-deckard is on a distinguished road
Not on a sailboat but on our fishing boat anyway same difference. I had a 48lb thrust trolling motor 24v though but go most of the afternoon trolling aroung on 2 car batteries sorry couldnt give exact size of the batteries but they were just normal batteries. Anyway duno if thats anyhelp at all but good luck to ya.
Reply With Quote Quick reply to this message Share with Facebook
  #4  
Old 06-17-2012
asdf38's Avatar
Senior Member
 
Join Date: Jul 2010
Posts: 724
Thanks: 1
Thanked 8 Times in 8 Posts
Rep Power: 5
asdf38 is on a distinguished road
Re: Trolling Motor to Battery Bank?

Wait this is all on the compac 16? I would keep it simple, why have 2 banks for such a small boat? If you did I would make the 2nd bank a small gell battery or something just for an emergency but I don't see the need. Otherwise, you need to do the math. Look up the motor current draw, look up your batteries and solar panel and calculate it all out. Check that the wiring and switches are properly rated. I wouldn't think the panel would be properly rated for a trolling motor but I could be wrong.
Reply With Quote Quick reply to this message Share with Facebook
  #5  
Old 06-17-2012
Senior Member
 
Join Date: Feb 2008
Location: N. VA
Posts: 656
Thanks: 0
Thanked 1 Time in 1 Post
Rep Power: 7
dacap06 is on a distinguished road
Send a message via Yahoo to dacap06
Re: Trolling Motor to Battery Bank?

Snyder,

You should know at the outset that appropriate electric propulsion costs quite a bit more to buy, but quite a bit less to operate. Unless you are flush with cash go with a gasoline outboard.

First, let's talk about the meaning of appropriate as it applies to your application. I am not at all sure that a trolling motor would be the best choice as auxiliary power for a sailboat. It will work, of course, but a trolling motor is designed to move a boat slowly and quietly. A better choice for electric primary propulsion, IMO, is to find an electric motor designed for the purpose.

You'll need to determine what size electric motor you'll need. Practical Sailor looked at three electric motors in their article Practical Sailor Compares 3 Electric Outboards. The Torqueedo 801L (a 2HP electric outboard) pushed their 19 foot Cape Dory at 4.5 kts at maximum output. That is realistic; I have a Travel 801L myself and it drives my dinghy (an 8' porta-bote) very nicely. I'd say 2 or maybe even 2.5 should be about right for you application and should give you reasonable speed even in chop and headwind.

Now that you know the motor size, what do you need to power it? The 2HP Torqueedo runs at 24 volts. The 2.5 HP Ray electric outboard runs at 36 volts. Clearly, you'll need a separate electrical system. The external battery model equivalent to the Torqeedo looks to be this one. Torqeedo has an interesting page that argues strongly for lithium manganese oxide batteries. They sell such a large 24V battery product but you'll pay for it. I'd recommend an appropriate number of golf cart batteries to get the voltage you need (4 for the Torqeedo, 6 for the Ray). They are designed for the kind of current draw you'll be producing with the electric outboard.

Finally, there's the price. Electric outboards are still very new, rather immature as technology goes, and change often. Ergo the price is still high so the vendors can pay for ongoing R&D. The Torqeedo listed above will set you back about 3 boat bucks, the Ray will set you back 4. Also figure $150 per battery for really good, high capacity golf cart batteries and at least $500 for wiring, trays, hardware, and an appropriate intelligent charger. Yikes.

So now you know why I suggested you stick with a gasoline outboard.
__________________
T. P. Donnelly
S/V Tranquility Base
1984 Islander 30 Bahama
Pasadena, MD

Last edited by dacap06; 06-17-2012 at 01:54 PM.
Reply With Quote Quick reply to this message Share with Facebook
  #6  
Old 06-17-2012
Senior Member
 
Join Date: Sep 2006
Location: Texas
Posts: 526
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 9
CapnBilll is on a distinguished road
Re: Trolling Motor to Battery Bank?

This is a compac 16. A trolling motor will get that boat from the dock to a clear area to raise the sails no problem.

A 45lb trolling motor will draw about 50amps, or 50amp/hrs per hour. So a 50amp hour battery, (average car battery), will run it about 1 hour. BUT a car battery is not deep cycle so it will only do this a few times.

The wheel chair batteries ARE deep cycle, most likely gel cells. What is the amp hour rating? I've seen from 35A/h to 75A/h. Running a trolling motor should be close to the amount of current needed to run a wheelchair.

Can the panel handle the load? ...Maybe. You would need to install a 50 amp breaker, and run 8 guage or better wire from battery pack to motor.

I would run a seperate wire direct from battery pack to a cutoff switch to motor.

Should you install a cutoff switch on the battery pack? YES, always. Make it well marked and accessable.

Murphy's Law says something will short out and catch fire in the middle of the night, and you will lose all power and lights. Thats when being able to reach for a readily accessable cutoff switch that isolates the battery pack, eliminating the power for the fire, is a great help.

Good luck. For your boat a small trolling motor should be fine, and propel you about 3 knotts.
__________________
The Sun has Risen on a New Day filled with the Promise of Adventure.
Reply With Quote Quick reply to this message Share with Facebook
  #7  
Old 06-17-2012
snider's Avatar
Senior Member
 
Join Date: Jun 2006
Location: Charleston, SC
Posts: 284
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 9
snider is on a distinguished road
Re: Trolling Motor to Battery Bank?

I appreciate all of the input. You guys are right the panel probably isn't rated for that much load. I'll have to double check but I think the two wheelchair batteries are 12V 36amps each. So that gives me 72amps. I would like to have 100amps for the trolling motor so I think I'll add one more 36amp wheel chair battery and run the trolling motor directly to the battery bank. I am going to install a master shutoff also. If I'm correct I install it close to the battery on the positive side? Should I then branch off for the trolling motor after the cutoff switch? Should I install a separate cutoff switch for the trolling motor say in the cockpit or just leave it open at the plug, or if the motor is hooked up just leave it connected? I'm probably overthinking this but electronics is one system I don't have the best grasp on and I just want to learn and do it right.

Dacap, I'm thinking of $300 max for a trolling motor. The boat is primarily for my wife otherwise we would just go without an engine and get a couple of long oars. We've owned 3 previous boats without engines, one that was larger, and sailed them around Charleston harbor as well as offshore. I actually prefer that, however I'm not sure she's ready for that alone. So she just needs something to use for docking. Ideally we'll eventually get her going without an engine. Again thanks for the ideas. I would ideally get a 6hp 25" Tohatsu and share it between her 16 footer and my 22 footer, as I don't have a motor for my boat either.

A picture is worth a thousand words so I'll get one up soon. Plus I just want to show off her new boat...lol!!!
__________________
Brandon
Charleston SC
Starwind 223 & Compac 16
Reply With Quote Quick reply to this message Share with Facebook
  #8  
Old 06-17-2012
Senior Member
 
Join Date: Feb 2008
Location: N. VA
Posts: 656
Thanks: 0
Thanked 1 Time in 1 Post
Rep Power: 7
dacap06 is on a distinguished road
Send a message via Yahoo to dacap06
Re: Trolling Motor to Battery Bank?

I always get a little worried about someone who has 3 kts of propulsion and they need to fight 4 kts of current, the combined result of river current and ebb tide.

There's a big difference in full out auxiliary propulsion and maneuvering at the slip. If you only want to use the trolling motor for docking purposes and your slip isn't in significant current, it should be fine.
__________________
T. P. Donnelly
S/V Tranquility Base
1984 Islander 30 Bahama
Pasadena, MD
Reply With Quote Quick reply to this message Share with Facebook
  #9  
Old 06-17-2012
snider's Avatar
Senior Member
 
Join Date: Jun 2006
Location: Charleston, SC
Posts: 284
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 9
snider is on a distinguished road
Re: Trolling Motor to Battery Bank?

Thanks,
We are generally pretty picky about choosing slips that we can sail into and out of, however the marina's really frown upon it. So yes that is what the motor would be for. Sorry I should have been clearer. It's usually pretty windy here. We've only once had to anchor because we couldn't beat wind and current. Had a red stripe then got back underway in about 30 mins
__________________
Brandon
Charleston SC
Starwind 223 & Compac 16
Reply With Quote Quick reply to this message Share with Facebook
  #10  
Old 06-17-2012
MarioG's Avatar
Senior Member
 
Join Date: Sep 2009
Posts: 404
Thanks: 0
Thanked 6 Times in 6 Posts
Rep Power: 6
MarioG is on a distinguished road
Re: Trolling Motor to Battery Bank?

I have a 30 pound thrust motor on my dinghy with a 35 w solor panel that works out great. I have ran from the boat in the anchorage in Boot key to the city docks a few times a day with no problem. I think your idea would work well but wouldn't run thru the panel unless you upgrade to heavyer wire for the motor.
Reply With Quote Quick reply to this message Share with Facebook
Reply

Quick Reply
Message:
Options

By choosing to post the reply above you agree to the rules you agreed to when joining Sailnet.
Click Here to view those rules.

Register Now

In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Solar charger size - trolling motor battery drcoop Electrical Systems 2 05-13-2012 04:56 PM
Trolling motor for dingy? Andyman Gear & Maintenance 7 05-20-2008 11:12 AM
trolling motor for the dingy? hertfordnc Gear & Maintenance 0 05-05-2008 10:30 AM
trolling motor on dinghy RandyonR3 Gear & Maintenance 1 11-10-2007 11:41 PM
Does anyone use a Electric Trolling Motor poopdeckpappy Gear & Maintenance 23 10-19-2007 10:08 PM


All times are GMT -4. The time now is 12:17 PM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.