Glen-L.com

For an old Structural/Civil engineer.

The center post on the cig. lighter is positive. Right?

I have some LED parade lights that need to go straight to the batttery and I have to cut the plug off.

Bill

_________________
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

Yes Bill, that is how I wired my 2 accessory sockets on my boat with the center tap to pos + and the perimeter tap to neg - and all of my DC devices have been working. Leland

Leland

Thanks for the conformation. I had to order these lights and don't want to blow them before they are even used. As I remember, diodes are unidirectional. It may not hurt them to try to go backwards. But, I don't have time to re-order.

I just remember that Wheat Bridge/Wet bridge... thing or something.

Thanks,
Bill

_________________
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

Yes Bill there is a + in the center.

I've wired LED s backwards,it doesn't blow them,they just don't work.

The instructions on some I had said to try reversing polarity if they don't work.

_________________
Boat building can best be defined as an endless series of
tragedies obscured by the occasional miracle, followed by a good bottle of beer.

Don't Dream Your Life, Live Your Dream

The center post is positive when the ground is negative. It's a bad assumtion to believe that all battery systems have a negative ground. You only have to go back to the 1970s to find a lot of Fords with positive grounds. The moral of the story is, When in doubt, check.

Good point on assuming neg ground.

Everything I've ever worked on was,but you are right that some old stuff was positive ground

_________________
Boat building can best be defined as an endless series of
tragedies obscured by the occasional miracle, followed by a good bottle of beer.

Don't Dream Your Life, Live Your Dream

Never owned any mid-late '60's British cars, eh? Lucky man!

Actually, anything made prior to 1970 can be a crap shoot, especially British, and some Japanese engines. You really need to check the battery cables to be sure. Since Marine engines are, for the most part, slower to change than their automotive counterparts, anything inboard, and prior to 1972 needs to be verified per case. Some automotive mfgrs used both systems, Nash, DeSoto, Packard, Willys all used positive in some models, and neg in others... in the same year. Must have been allot of sparks flying around jumper cable time!

_________________
Some plan to stroll through Saint Peter's Gates, I plan to go through them at 150mph... backwards... in a screaming ball of flame, with a glimmer belt wrapped around my head, and a NOx button in my hand.

Interesting discussion on positive ground systems, I would not wire a positive ground system today in Bill's new Tahoe boat or Tug wherever he was putting the accessory sockets for the LED lights. Please show us the pictures of the lighted boat Bill.

http://en.wikipedia.org/wiki/Cigar_lighter_receptacle

Regardless of if the ground is positive or negative I would always wire the center contact point to positive and the outer can of the receptacle to negative otherwise when you plug the accessory into the socket the polarity delivered to the device will be incorrect and if the device is a fogiving DC motor it will run backwards. If one were to wire a positive ground system it would be prudent to make sure the can on the socket is well insulated so it doesn't contact the frame or anything that is positively grounded. No wonder those early model Nash Ramblers had vacume driven wiper blades if it were a positive ground DC motor you would have to drive backwards in the rain because the wiper motor would run backwards.

Bill - I just purchased 2 accessory outlets for my cockpits "just in case" I ever need some power - like the kids tubes and other things that need air. They look like cigarette lighters but not. Is this what you are installing?

In reading the wiring. The center post is positive. The ground attaches to a side tab.

_________________
Dave

My Riviera build - the Midnight Cry Project

Video of Midnight in Action
Blog

Few things in the world measure up to the thrill and satisfaction of boating in a boat that you built.

That is the type of glug on these lights. I had to cut the plug off and make clips to go straight to the battery.

Bill

_________________
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

I have never had good luck with cig lighter style plugs on boats.....corrosion!!

I cut all mine off and wire in two conductor,polarized flat plugs that look like trailer light plugs.

I've never had an issue with these,even for high draw spot lights.

The down side is you need to have a wire with the plug hanging somewhere,but I just tuck it somewhere

_________________
Boat building can best be defined as an endless series of
tragedies obscured by the occasional miracle, followed by a good bottle of beer.

Don't Dream Your Life, Live Your Dream

I installed 2 SeaFit (WestMarine) Stainless Steel 12v receptacles (cigar lighter sockets) 10 years ago and have had no corrison problems but my boat is 50 miles inland from ocean salt spray and in enclosed dry storage when not in use. I like Warren's idea but it requires reworking the plug for every accessory to be used. I agree the spring contact friction style cigar lighter style plug is not a good design but it is the defacto 12v standard and is what comes with radios, cell phones, GPSs, inflators, 12v LED rope lights.

You guys went way overboard on this one. But, Thanks.

This is for 2 strings of LED lights to go on the Mini-Tug for a 2 mile parade. I'll just be attaching directly to the battery terminals for an hour or so.

Bill

_________________
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

But Bill - you have to take care of Lola (s)

_________________
Dave

My Riviera build - the Midnight Cry Project

Video of Midnight in Action
Blog

Few things in the world measure up to the thrill and satisfaction of boating in a boat that you built.

Good , now lets move along to your next project, a new and improved tugboat project.