Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 27-03-2007, 14:20   #1
Registered User

Join Date: Jun 2006
Posts: 6
Light on the Outboard

I've seen many dinghy outboards with a single white light attached to the top cover to provide for the required running light (white light all around). It seems to come on when the outboard is started and goes off when the engine is stopped.

I've got a Honda 20hp outboard (with generator) where I would like to install a lite attached to the outboard cover - and have the light come on only when the engine is runniing. I can wire a light to the battary - but would have to put a switch in the circuit that I would likely forget to turn-off.

I'm assuming the light is a standard 12 volt post light. Does anybody know how to wire the light so that it just comes on when the engine is running?
__________________

__________________
rickfant is offline   Reply With Quote
Old 27-03-2007, 16:25   #2
cruiser

Join Date: Nov 2004
Posts: 4,525
Hi Rick,

As an alternative, you could try one of these:

West Marine: Series 23 Portable LED Lights Product Display

See the light on the far left. It has a suction cup and sticks right on the outboard. Being that it's an LED light, it uses very little juice. I used mine for 6 months last year and never had to change the batteries once. I live at anchor and was chartering, so I ran to and from shore hundreds of times.

Good little light, no wiring or complicated project. Moisten and stick to the outboard.
__________________

__________________
ssullivan is offline   Reply With Quote
Old 27-03-2007, 16:34   #3
Senior Cruiser
 
senormechanico's Avatar

Cruisers Forum Supporter

Join Date: Aug 2003
Boat: Dragonfly 1000 trimaran
Posts: 5,827
You need a diode (preferably a Schottky) in series with the alternator output to the battery with the light connected between ground and the alternator output terminal. A Shottky diode capable of taking full battery charging current might need a small heat sink, but they're not expensive and are available at electronic supply houses.

Another way would be to take the output directly from the alternator windings before the internal diodes, but you would need some kind of voltage regulation for the light as it would burn out with any RPM much over idle speed.

I wish I could attach a diagram for you.

Steve B.
__________________
senormechanico is online now   Reply With Quote
Old 27-03-2007, 18:18   #4
Marine Service Provider
 
AnchorageGuy's Avatar

Join Date: Mar 2003
Location: Wherever the boat is!
Boat: Marine Trader 34DC
Posts: 4,618
most of these small outboards don't have alternators.
__________________
Chesapeake Bay, ICW Hampton Roads To Key West, The Gulf Coast, The Bahamas

The Trawler Beach House
Voyages Of Sea Trek
AnchorageGuy is offline   Reply With Quote
Old 27-03-2007, 20:32   #5
Senior Cruiser
 
Starbuck's Avatar

Cruisers Forum Supporter

Join Date: May 2005
Location: Long Beach, CA
Posts: 827
Not alternator.
Not generator.
Rectifier.
__________________
s/y Elizabeth Catalina 34 MkII
"Man must have just enough faith in himself to have adventures, and just enough doubt of himself to enjoy them." G. K. Chesterfield
Starbuck is offline   Reply With Quote
Old 27-03-2007, 23:54   #6
Senior Cruiser

Cruisers Forum Supporter

Join Date: Dec 2006
Location: Seattle
Boat: Cal 40
Posts: 2,401
Images: 7
My impression is that most manufacturers have chargers on their small engines now. I just checked on the Honda, Yamaha and Johnson websites, and they all have chargers on their engines down to 10 hp. The output is only 5-10 amps on this size engine.

A generator is something that produces electricity from mechanical energy. Common usage of generator, back when the earth was hot, was if you had a generator on your car, it was a device with a commutator that put out DC. Commutator (electric - Wikipedia, the free encyclopedia)

An alternator is a generator that produces AC electricity.

A rectifier is a device that converts AC to DC. It can be as simple as a single diode. An alternator needs a rectifier in order to produce DC to charge a battery. They are typically built into alternators (The kind you find on cars and inboards).

A diode is a check valve, allows flow one way, but not another. Steve's idea with the Schottky diode allows the electricity to flow from the engine to the battery when the engine is running as the voltage of the engine is higher than the battery. When the engine is off, the voltage on the engine side is lower than the battery, and so no electricity from the battery reaches the light. I believe Steve is saying to use a shottky diode because they can have a low forward voltage drop. The small outboards that I'm familar with (say old) did not have a regulator and so the voltage drop is not really a concern, but if the newer engines have a regulator, then even the smaller drop across the shottky diode will affect how well the battery charges.

................diode
engine_______|>________+ battery -
.............\_______light___________/

Is this what you had in mind Steve?


John
__________________
cal40john is offline   Reply With Quote
Old 15-04-2007, 07:36   #7
Registered User

Join Date: Jun 2006
Posts: 6
Thanlks for all the replies; I've looked in my local marine stores and have not seen any pacakge (or individual components) that would allow the kind of diode structure described. I'll keep looking.

I wonder If I just wire the light to the oil light?
__________________
rickfant is offline   Reply With Quote
Old 15-04-2007, 10:18   #8
Senior Cruiser
 
senormechanico's Avatar

Cruisers Forum Supporter

Join Date: Aug 2003
Boat: Dragonfly 1000 trimaran
Posts: 5,827
................diode
engine_______|>________+ battery -
.............\_______light___________/

Is this what you had in mind Steve?

Exactly. Whenever the engine is running, the light comes on but it can't discharge the battery at any time.

Steve B.
__________________
senormechanico is online now   Reply With Quote
Old 29-04-2007, 19:55   #9
Registered User

Join Date: Mar 2007
Location: Canada East Coast
Boat: Oday 23
Posts: 16
Wow...Schottkey diodes, forward and reverse bias voltages..Yeeks. Egads, even. A sailor ain't a sailor ain't a sailor anymore.

I liked what SSullllivan ssaid. Moisten and SSStick it on. Yeahhhhh!
'Tis a joy to be sss..sss..simple.
__________________

__________________
SkipperCanuck is offline   Reply With Quote
Reply

Tags
outboard

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
LED Anchor Light Update 29cascadefixer Electrical: Batteries, Generators & Solar 121 04-07-2012 16:58
Diesel Outboard ? trout888 Engines and Propulsion Systems 55 13-02-2011 22:43
waterproof outboard beau Powered Boats 9 16-12-2006 21:21
Reverse Polarity Light alanperry Electrical: Batteries, Generators & Solar 24 06-09-2006 04:13
Outboard engine and solar power charging THamel Construction, Maintenance & Refit 2 19-05-2003 23:28



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 12:33.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.