Go Back   Cruiser Log World Cruising & Sailing Forums > Cruising Forums > The Bosun's Locker > Power & Electronics
Cruiser Wiki

Join Cruiser Log Today

Reply
 
Thread Tools Search this Thread Display Modes
 
Old 05-08-2007, 09:31 PM   #1
Moderator
 
JeanneP's Avatar
 
Join Date: Jul 2004
Posts: 2,098
Default

I want to use some LED lights that presently run on batteries in our boat. The nicest one has 3 settings - a high, medium, and low setting. It uses 4 AAA batteries, or 6V DC. I can find cigarette-lighter plug type DC-DC adapters, but for wiring these lights into the boat, that's not an option. I assume that there are some sort of diodes (or whatever) in these adapters to step down 12V to 6V (or 4.5V, etc. as sold). How does one find these step-down adapters to wire in line so I can wire these lights directly to the house power?

There's GOTTA be a solution! (doesn't there?)
__________________

__________________
In 1986 we went cruising for a few years. After 20 years and 50+ countries and several oceans, we are STILL "cruising for a few years".

SY WATERMELON |
MV WATERMELON (New) | Cruiser's Dictionary, free ebook

= Cruiser's Dictionary, North America,
JeanneP is offline   Reply With Quote
Old 05-08-2007, 09:53 PM   #2
Ensign
 
KaptainKen's Avatar
 
Join Date: May 2006
Posts: 9
Default

JeanneB;

Here's a link to a multi-voltage DC-to DC step down converter: http://www.powerstream.com/dc6.htm It may do the job, but at $15.75 each not exactly cheap. How many would you need?

You could wire two of your LEDs in series. Both of the ones in the series would have to be "On" at the same time and each would "see" 6 volts.

Keep in mind that your 12 volt system is only 12 volt nominal. When the engine is running and the alternator working properly it's output is usually in the neighborhood of 13.5 volts or so. Also your voltage could be less after sitting at anchor for a while or while sailing.
__________________

__________________
Anything worth doing is worth doing to excess!
KaptainKen is offline   Reply With Quote
Old 05-09-2007, 12:43 AM   #3
Admiral
 
MMNETSEA's Avatar
 
Join Date: Oct 2004
Posts: 3,067
Default

Quote:
Originally Posted by JeanneP View Post
I want to use some LED lights that presently run on batteries in our boat. The nicest one has 3 settings - a high, medium, and low setting. It uses 4 AAA batteries, or 6V DC. I can find cigarette-lighter plug type DC-DC adapters, but for wiring these lights into the boat, that's not an option. I assume that there are some sort of diodes (or whatever) in these adapters to step down 12V to 6V (or 4.5V, etc. as sold). How does one find these step-down adapters to wire in line so I can wire these lights directly to the house power?

There's GOTTA be a solution! (doesn't there?)
----------------------------------------------------

Hi Jeanne,

Not knowing what type of LED lights we are discussing - probably need a few alternative options :-

1) I used a mobile telephone charger (the type that is designed to plug into a car's cigarette lighter) in this instance the Nokia's terminal fitting on the end of the charger' wire I cut off and connected in line to provide voltage to my cockpit's LED light which I leave on when I am away from the boat. ( The cost about a dollar fifty)

MVC_062F.JPG

2) Using 2 resistors of equal value that are rated for 50% more than the max current that your LEDs will draw. for example you can use two 500 ohm resistors rated at 10W soldered end to end and you would tap in the middle to get 6V. you can also run a capacitor in parallel with the second resistor to help hold the voltage steady (250uf should do it). In reality the voltage would be between 6V and 7.5V depending upon your House voltage output.

see diagram below.

+12V

|

|

R1

|

*------>tap here for 6V --->LED +tive wire

|\

C R2

A |

P |

| |

|/

*--Ground-------------------->LED -tive wire

If you have a Radio Shack store or equivalent near by, get them to check the LED's current

demand - they can also advise on the schematic I unearthed from another project.

PS . Jeanne , I will search for an IC solution using a very cheap chip - the 7086 ......

and a wiring diagram and come back to you. It is somewhere ?????

FOUND IT ;- here is a picture of the 7805 and a dimension drawing of the 7806

Both essentially same size (about the size of peter's thumb nail) They cost very little from any electronics parts shop - ask them to give you the most simple wiring diagram.

78xxs_Series_Volt_Reg_.jpg

Richard
__________________
MMNETSEA is offline   Reply With Quote
Old 05-09-2007, 01:22 AM   #4
Admiral
 
MMNETSEA's Avatar
 
Join Date: Oct 2004
Posts: 3,067
Default

Hi all,

12 Volt Doctor's Practical Handbook

While we are on the subject of electrics and electronics

Most of which leaves me in the DARK!

I was reminded that the 12 Volt Doctor's Practical Handbook has been completely revised and updated. This timeless classic is now even better.

The 12 Volt Doctor's Practical Handbook provides a clear and useful guide for electrical system troubleshooting. It covers such subjects as lightning protection, engine instruments and alarms. The chapter on Electrolytic Corrosion is the most definitive text available.

The new 12 Volt Doctor's Practical Handbook has an expanded troubleshooting section. ISBN . 1 878797 13 1

Since it is illustrated with simple drawings you will be able to use the 12 Volt Doctor's Practical Handbook even if you have not previous electrical experience.

With the "Doctor" you can: Fix electrical problems on board before calling in expensive outside technicians.

# Learn and understand basic electricity.

# Maintain your own 12 volt system.

# Understand and use "zincs" effectively.

# Isolate and repair hard to diagnose electrical problems.

I think the publisher is Weems and Plath (spelling???)

BOOK SEARCH HERE (enter "12 Volt Doctor" in the "SEARCH" box)

.
__________________
MMNETSEA is offline   Reply With Quote
Old 05-09-2007, 08:11 AM   #5
Lieutenant
 
Join Date: Jan 2007
Posts: 84
Default

If your boat has 6v batteries in series, you could run a seperate wire and fuse for the lights or you could get 2 small 6 volt rechargable batteries for this.
__________________
Cruising Bahamas
Lynx is offline   Reply With Quote
Old 05-09-2007, 11:07 PM   #6
Moderator
 
JeanneP's Avatar
 
Join Date: Jul 2004
Posts: 2,098
Default

Thank you for all the suggestions. We need all of them if we're going to do this to MY satisfaction.

Now to explain.

We have halogen lights on the boat. In the cabins they have plastic lenses. In one cabin the light got dislodged from the fitting and fell down from its mounting, and burned its way through the plastic lens. The high power consumption of these lights, and the heat they generate, bothered me before this little melting episode, and now I'm obsessed with replacing all of the halogen lights with LEDs.

We bought a fixture from DrLED to replace the cabin light, but it's not very attractive, it's very expensive, and I don't want that in the saloon. So I've been picking up LED lights and trying them. These are sold to homes for places where they don't/can't wire a light, and they run on AAA batteries. The first set I used just didn't have the right light for prolonged use, so I wasn't interested in hard wiring them in. I recently picked up a different light that I'd like to try. It's quite attractive and has 3 light levels - very low to serve more as a night light, medium light and bright light. There are 2 yellow LEDs for the very low level, and 6 white LEDS for the other two higher levels. This one would be most inconvenient to run on batteries for my purposes. The light has a 3-level switch, I could put four of them in the saloon to replace the four existing halogen lights that are all either on or off, no way to turn them on individually without rewiring them. If we're going to rewire, I would like the lights to be the LED lights.

Peter is good at wiring, but he wasn't sure how to approach this. We now have two choices

We shall see. I figure I'll take photos and if it all works out to my satisfaction I'll plonk it into the cruiser's Dictionary. I'm building up a nice little file of additions and revisions to it.

Now let's hope this post goes through. My last two are lost in the ether somewhere. I should have my good computer back next week (fingers crossed).
__________________
In 1986 we went cruising for a few years. After 20 years and 50+ countries and several oceans, we are STILL "cruising for a few years".

SY WATERMELON |
MV WATERMELON (New) | Cruiser's Dictionary, free ebook

= Cruiser's Dictionary, North America,
JeanneP is offline   Reply With Quote
Old 05-10-2007, 12:28 AM   #7
Admiral
 
MMNETSEA's Avatar
 
Join Date: Oct 2004
Posts: 3,067
Default

Hi Jeanne, The 7806

Found a schematic for the IC 7806 DC voltage regulator - but not able to reproduce here.

However, if you look at the photo of 7805 (the 7806 looks exactly the same) you will see 3 pins coming out of the IC :-

1)The bottom pin is the pin to connect the positive 12volt wire from your house circuitry

2)The centre pin is the pin to connect the negative 12v wire AND the

negative 6volt wire to your LED fitting.

3)The top pin is the pin to connect the positive 6volt wire to your LED fitting

Notes : It may be necessary to connect the IC 7806 to a tiny heat sink - but this depends on the current drawn by your LED Lights, this is easily done by fixing the Ic to the heat sink with small self tapping screw ( the heat sink can be a small piece of flat aluminium or copper )

The number 7806 means that it is 12v >> 6v in the 78 series - 7809 would be 12v >> 9v in the

78 series and so on.

This little component is easy to install and being small is ideal for the job. The only thought I have is where to install it your present 12v line - because of voltage loss if put in a long way from its destination. Test should reveal any significant loss.

Good luck

Richard
__________________
MMNETSEA is offline   Reply With Quote
Old 05-10-2007, 10:55 AM   #8
Moderator
 
JeanneP's Avatar
 
Join Date: Jul 2004
Posts: 2,098
Default

Thank you again, Richard. I think that this will do it, though we might not get a chance to try it for a few weeks. We head back to the boat in a week, but will be very busy getting it ready to be loaded onto the transport to Finland. Unless we are very efficient, we won't get to this until some time in June. But I'll find all the bits and pieces beforehand.

In order to use these new lights I'm going to have to find some kind of decorative housing because I don't want to damage the head liners in the boat. That will give us lots of space to put heat sinks, resistors, whatever, right at the lights themselves. I hope that it works.

Unfortunately our house batteries are 12V, not the 6V in series we're used to.

These lights are made by Cyberlux Corp., http://www.cyberlux.com/list.php

They're called "Everon" and they run on 4 AA batteries, not AAA as I first said. I'm aware that they're not "marine grade", but they're worth a try.

In a way, this is rather fun. MV Watermelon is new enough that we don't have a whole lot of maintenance/repair issues which leaves me a bit too much time to think about making changes.

Will keep you all posted.
__________________
In 1986 we went cruising for a few years. After 20 years and 50+ countries and several oceans, we are STILL "cruising for a few years".

SY WATERMELON |
MV WATERMELON (New) | Cruiser's Dictionary, free ebook

= Cruiser's Dictionary, North America,
JeanneP is offline   Reply With Quote
Old 05-17-2007, 01:27 AM   #9
Ensign
 
Join Date: Jun 2005
Posts: 3
Default

Guess I would pass for electrical guru. But it seems like you have gotten a bunch of good advie. Don't use reisitors to drop voltage that is just a waste of power. After all that is the whole reason to use LEDs. It's sue not for the lovelyglow! I would consider using neon instead. You can get regular household type fixtures that use stamdard bases like what you would see on 40 to 150 watt, 120 VAC lamps. Google 12 volt neon lights. You will find RV suppliers offering 12v replacment bulbs. These are remakably RF interference free unlike the thin-lights sold for marine use. Just a thought they are much cheaper and the light quality is much better on your eyes!

John
__________________
BADick is offline   Reply With Quote
Old 05-17-2007, 09:10 AM   #10
Ensign
 
Join Date: May 2007
Posts: 1
Default

If you want to do it efficiently, then you need a DC-DC switching converter - known as a buck converter by EEs.

The resistor is not a good solution, not only does it waste power (the same amount of power is dissipated in the resistor as heat as is used by the LED light), the actual voltage seen by the LED unit will vary depending on the brightness setting you select. The 7805 series of three terminal regulators are little better - they are essentially clever resistors and will waste as much power as the resistor but without the voltage variation.

I don't recommend the 'two units in series' as you may end up with a situation where the 12V is seen by one of the units alone (i.e. when the second unit is off) and it could damage it.

Personally, I'd pickup a DC-DC converter that could supply all of the LED units in parallel, wire it in somewhere and then wire them all off it. Use one intended for car or truck applications as it will have the additional protection needed for the typical error conditions seen on a 12V system (assuming you have an alternator supplying a battery).

Andy
__________________
pteron is offline   Reply With Quote
Old 05-18-2007, 02:34 AM   #11
Ensign
 
Join Date: Apr 2007
Posts: 10
Default

I have not tried this but the theory is sound because the LED lights draw very little power. The voltage drop you are looking for can be achieved with a "Zenner" diode. This is a diode that when connected as shown will drop a fixed voltage across it. 6.8 volts is a common value sometimes written as 6V8. You connect the cathode (usually marked with a band) to the +ve 12V (this is backwards to a normal diode). A 1 or 2 Watt capacity would be best for each lamp.

+12V -------------|<|-------------------6V to LED

Zenner Diode

Cathode Anode

You can buy them from Tandy and electronics suppliers. To adapt your lights I would solder a small fuse eg 200mA slowblow and a zenner diode in series in the battery compartment of the lamp and run the wires into your 12V lighting circuit. The zenner diode will generate a similar ammount of heat to the LED light. Parts are cheap and buy a few spares and tape them in the battery comparment too. This makes your lamps effectively 12V devices.

So many choices!!
__________________
sirlespat is offline   Reply With Quote
Old 05-18-2007, 04:04 AM   #12
Admiral
 
MMNETSEA's Avatar
 
Join Date: Oct 2004
Posts: 3,067
Default

SIRLESPAT - great post - now Jeanne is getting somewhere -

Thanks Much !!!
__________________
MMNETSEA is offline   Reply With Quote
Old 05-19-2007, 05:16 AM   #13
Ensign
 
Join Date: Oct 2005
Posts: 18
Default

Quote:
Originally Posted by JeanneP View Post
I want to use some LED lights that presently run on batteries in our boat. The nicest one has 3 settings - a high, medium, and low setting. It uses 4 AAA batteries, or 6V DC. I can find cigarette-lighter plug type DC-DC adapters, but for wiring these lights into the boat, that's not an option. I assume that there are some sort of diodes (or whatever) in these adapters to step down 12V to 6V (or 4.5V, etc. as sold). How does one find these step-down adapters to wire in line so I can wire these lights directly to the house power?

There's GOTTA be a solution! (doesn't there?)
LED's have a silicon junction that can only normally handle 25 ma before they are destroyed. Superbright LEDS probably have a higher current rating. But using Ohm's law v=i X r you can work out current rating needed at 12 volts. So you don't have to worry about volts when using LEDS. Example in this case: 6 v = 25 ma x R

6v/25 K ohms = R answer = .24 K ohms or 250 ohms thus the best resistance in series is 270 Ohms.

Now for 12 volts : 12v = 25 ma x R ; answer = 480 ohms and the best fit resistor here is 490 Ohms at 2 watts. To determine current involved with your light one would use multi-meter and measure resistance across the termnals of light when not connected to anything else. One way you will get "OL" reading and the other, which is the way current will flow, will give you a reading, my guess, will be about 120 ohms. You will notice resistance reading change when selecting different brightness levels; this in effect is bringing different resistors in series with LEDS. These reistors must be inside unit. Anyway using 120 Ohms - 6 v = I x 120; answer = 50 ma; now at 12 volts = 50 ma x R; answer = 240 Ohms. So to use 12 volts you would use a 270 Ohm (this is standard resistor value) at 2 watts rating wired in series with light.
__________________
llamedos is offline   Reply With Quote
Old 05-19-2007, 08:29 AM   #14
Retired Mod
 
Lighthouse's Avatar
 
Join Date: Mar 2007
Home Port: Durban
Posts: 2,984
Default

@Llamedos



Thank you for that info. We hope to see more of your great contributions.
__________________

__________________


The World Cruising & Sailing Wiki

Help to build this free, online World Cruising Guide.

"Built by cruisers, for cruisers''

I've Contributed to the Cruisers Wiki: Most sections
Lighthouse is offline   Reply With Quote
Reply


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

Advanced Search
Display Modes

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
Electrical Problems And Propane Don't Mix redbopeep General Cruising Forum 6 11-12-2010 06:14 PM
Water Turbine Driven Electrical Generator Harbor_Pilot Other Equipment 11 03-03-2007 10:57 AM

Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

RV & Travel Trailer Communities

Our RV & Travel Trailer sites encompasses virtually all types of Recreational Vehicles, from brand-specific to general RV communities.

» More about our RV Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities


All times are GMT. The time now is 08:31 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2016, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.0