Wiring / Voltage

Feb 4, 2015
5
Capital Yachts Neptune 24 Marina del Rey
Wiring / Voltage question

Hi All,

I have a basic electrical question:

I currently have two 12v batteries on the boat connected parallel for 12v output. I want to use an electric trolling motor that requires 24v. If I reconfigure the two batteries to generate 24v will that affect all of the electronics on the boat? Do I need to do anything to lights, pumps, radio, etc to accommodate 24v?


Thanks!
Nick
 
Sep 25, 2008
7,435
Alden 50 Sarasota, Florida
Only if you want to buy all new electronics. Everything you mention cannot tolerate higher voltages. You could install a step-down transformer to feed all your 12v devices but unless you have the expertise to build one to avoid the expense of purchasing all the apertanent switching system, doing what you propose is impractical.
 

ALNims

.
Jul 31, 2014
208
Hunter 356 Huis Ten Bosch Marina, Sasebo, Japan
Re: Wiring / Voltage question

Your best bet would be to buy a new set of batteries whose sole purpose is for the trolling motor. Don S/V ILLusion is 100% correct in his assessment.
 
May 24, 2004
7,173
CC 30 South Florida
There is one solution by utilizing just a single battery for the 12V circuits and then connecting on the two batteries in series for a separate 24V circuit. Connect the batteries as follow;

Positive (+) of battery#1 to negative (-) of battery #2

Connect 12V circuit (+) lead to positive of battery #1 and Negative lead of 12V circuit to (-) terminal of same battery #1

Then connect the 24V circuit positive lead (+) to positive of battery #1 and the negative lead to negative of battery #2.

The end result is that you will have two separate circuits; one will be your existing to handle all the 12V instruments and fixtures from battery #1 and a second separate circuit dedicated to the motor using both battery 1 and 2 in series for 24 V. You must understand that your house 12V circuit will now only have half of the storage capacity it had previously plus will be asked to provide additional power to combine with battery #2 to supply the 24V power to the motor. You will have to perform an energy budget on how long you will have to run the motor and for how long you would need to run lights and electronics. If you wanted to retain your original storage capacity you could add a third battery #3 connected in parallel with battery #1.
 

LloydB

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Jan 15, 2006
927
Macgregor 22 Silverton
Although it would be possible to connect the batteries in series to make 24V for the motor and then tap off only one of the batteries for the 12V circuit it would cause unbalanced load on both batteries during use and recharge and cause early demise. ALNims suggestion looks best to me. A step down transformer not so much.
 
Feb 4, 2015
5
Capital Yachts Neptune 24 Marina del Rey
Lloyd- Probably not the best set up in terms of longevity, no. Thanks everyone!
 

weinie

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Sep 6, 2010
1,297
Jeanneau 349 port washington, ny
why does one need a trolling motor on a sailboat?
If you're fishing, just roll out a touch of jib.
Otherwise, I'd say a small outboard would be much more reliable.
 
Feb 4, 2015
5
Capital Yachts Neptune 24 Marina del Rey
I'm just planning on using it to get in and out of the slip. Don't have much use for an expensive outboard as we pretty much always have nice wind here, but I'm tired of sailing out of my slip - just too much work trying to to drift back into the dock/other boats.
 

Sumner

.
Jan 31, 2009
5,254
Macgregor & Endeavour 26S and 37 Utah's Canyon Country

Sumner

.
Jan 31, 2009
5,254
Macgregor & Endeavour 26S and 37 Utah's Canyon Country
I'm just planning on using it to get in and out of the slip. Don't have much use for an expensive outboard as we pretty much always have nice wind here, but I'm tired of sailing out of my slip - just too much work trying to to drift back into the dock/other boats.
A 12 volt 55 # motor won't have as much thrust as a 24 volt one will but it would sure make your life easier as far as the wiring and charging. I'm doing the final wiring on a 24 volt trolling motor for the Mac but also have another solar array charging it and want to do much more than just in and out of the slip, but if that was the case I'd go for a 12 volt one,

Sumner

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caguy

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Sep 22, 2006
4,004
Catalina, Luger C-27, Adventure 30 Marina del Rey
Weenie +1. I drag a lure all over Santa Monica Bay when I'm out and catch Bonito all of the time (when they are biting) under sail at 4-5 knots.
Where are you in MDR?
 
Feb 26, 2004
23,047
Catalina 34 224 Maple Bay, BC, Canada
You might want to buy Charlie Wing's book about electrical systems on boats.
 
May 24, 2004
7,173
CC 30 South Florida
Everything is a tradeoff, you get the dual availability of a 12V and a 24V circuits but will reduce the longevity of the dual circuit battery doing the heavy lifting. We were just discussing in another posting the fact that manufacturers do not know and cannot guarantee with any degree of certainty what the useful life will be for an individual battery. As long as the battery serving both circuits is not deeply discharged below 50% of capacity and is charged back to 100% after every use I would say that its chances of providing a long useful life could be as good as any.
 
Jan 19, 2010
12,565
Hobie 16 & Rhodes 22 Skeeter Charleston
I've used a 55# 12V trolling motor on a Coronado 25 for exactly the purposes you mentioned. No problems at all.
 
Jan 22, 2008
507
Catalina 310 278 Lyndeborough NH
For casual use you might get away with tapping 12 volts off the 24 volt set. If your charger attaches to each individual battery, it should keep the charge balanced. I have done this in the past when the 12 volt loads were low.

But the trolling motor will at some point draw the 24 volt system down so low, none of the 12 volt devices will get enough energy to function.

I have a separate 12 volt true deep-cycle battery sized for the electronics in addition to the set of four GC2 batteries providing 24 volts to a Torqeedo Cruise 2.0 electric outboard.

Since the boat is on a mooring, all batteries are recharged using solar panels. I go out once or twice a week and this works for me.