Which causes more damage to metal-on-metal contacts...

[parsethis]

...continuous current or intermittent current?

 

I am not talking about AC vs DC. Rather, continuous DC versus intermittent (switched) DC.

 

The long version:

I am considering changing out a lot of the wiring in my 1972 240Z to improve the electrical performance. Changes I hope to make include a high-output alternator, headlight relays, and a properly wired radio. 

 

My question concerns LED bulb upgrades for the turn signals. Because the resistance in the LED units is so low, it will cause issues for the blinker mechanism (too fast or constantly on). You can solve this problem by adding a resistor to the circuit (defeating one of the advantages of an LED unit-it's low draw) or by adding a flasher like this: https://www.superbrightleds.com/moreinfo/flashers-load-resistors/lf1-s-pin-universal-motorcycle-electronic-flasher/193/841/#/tab/Reviews

 

Now my understanding of the flasher unit is that when the circuit is closed (when I turn the blinker mech to a "left turn" position) it moderates the output so that it is intermittent, about a half second of power, following by a half second off. The installation theory is that you could put this on the input wire (between alternator/battery and the blinker mechanism) and it would moderate the signal whether you are turning left or right. 

 

So the question is, will this intermittent pulsing be worse for the metal-to-metal electrical contacts in the blinker mechanism than constant current?

 

The obvious follow-up is, is the current flow through the blinker mechanism already intermittent?

 

Appreciate your thoughts on the matter.

Edited August 28, 2015 by parsethis

[Miles]

For LED turn signal bulbs you don't need resistors. Use an electronic flasher unit availble at most parts stores. Been discussed here many times.

[parsethis]

For LED turn signal bulbs you don't need resistors. Use an electronic flasher unit availble at most parts stores.

Been discussed here many times.

 

I know you can use a flasher. I put it in my post.

 

Questions I didn't see addressed in previous posts:

 

When you use a flasher do you put it upstream or downstream of your blinker mechanism?

 

Does this placement change the actual wear on the mechanism (which is important because they are about $500)?

[Miles]

An electronic flasher costs less than $20.

 

Please don't take this as a put down, but you should study some books on automotive electronics

[NewZed]

 

So the question is, will this intermittent pulsing be worse for the metal-to-metal electrical contacts in the blinker mechanism than constant current?

 

No effect.  Once contact is made, the two sides are essentially one piece of metal, as far as electricity is concerned..

[parsethis]

No effect.  Once contact is made, the two sides are essentially one piece of metal, as far as electricity is concerned..

Excellent. Thank you.

[parsethis]

An electronic flasher costs less than $20.

 

Please don't take this as a put down, but you should study some books on automotive electronics

 

I should have been more specific. The cost is in reference to the blinker mechanism on the column, which is where the "metal-on-metal" contact I reference in my question is. I am trying to preserve the integrity of the switch so I don't have to rebuild it (again) or buy a new one.

Edited August 28, 2015 by parsethis

[Miles]

The best way to reduce loads on switches and wires is to install relays. A member here designed and sells through MSA relay kits for headlights and there are also relay kits for turn signals and running lights. Search here and at MSA. With relays the lights will be brighter and there will be less stress on switches. The member who makes the relay kits is named Dave and lives in Washington. Search in the VENDOR forum for relay kits.

 

 

 

http://www.thezstore.com/page/TZS/PROD/classic10l/12-4651

Edited August 29, 2015 by Miles

[Midri]

Little late to the party, but toggling current does do damage to the contacts at high enough current. Tap a piece of wire that's getting 12v from your battery to a piece of metal that's grounded to the the same battery and you'll see them blow each other apart slowly over time (basically how an arc welder works) Constant current is better, if mechanical contacts are being used; if you're using a 555 timer (like the common non mechanical blinker relays are) you'll be fine though, they never physically disconnect the metal and instead use MOSFET which do not suffer from fatigue like metal on metal switches do.

 

Bonus: Old blinker units (the kind that click) actually work via mechanical switch that switches back and forth based on internal temperature (relay gets hot, turns off, cools down, turns on, gets hot, turns of, etc) and that's why they tended to break after a while. They literally work by fatiguing the metal. Newer "digital" units use a circuit built around a 555 IC, a resistor, and a MOSFET. They can last forever if you don't get them too hot (which they won't do on their own)

Edited September 23, 2015 by Midri

[parsethis]

I guess what I was imagining when I asked this was, to use you arc welder analogy: Imagine you have an imperfect circuit where the contact point are not great and there is a bit of an arc. If you put an LED blinker relay "upstream" of this point the arcing is intermittent, it flashes between the points like a spark plug. If you put the same relay "downstream" of the blinker assembly the arcing IS constant, like you might see in an arc welder (if you just kept it in one place, which you wouldn't, but whatever...)

 

The general consensus is that this was all a lot of hoopla about a very minor part of the electrical system. Everything else that I have done (refresh blinker assembly, install flasher units, install LEDs) reduces the load so drastically that I can expect regular and consistent performance from here on out.

[Midri]

I guess what I was imagining when I asked this was, to use you arc welder analogy: Imagine you have an imperfect circuit where the contact point are not great and there is a bit of an arc. If you put an LED blinker relay "upstream" of this point the arcing is intermittent, it flashes between the points like a spark plug. If you put the same relay "downstream" of the blinker assembly the arcing IS constant, like you might see in an arc welder (if you just kept it in one place, which you wouldn't, but whatever...)

 

The general consensus is that this was all a lot of hoopla about a very minor part of the electrical system. Everything else that I have done (refresh blinker assembly, install flasher units, install LEDs) reduces the load so drastically that I can expect regular and consistent performance from here on out.

 

The ark would never be constant, regardless of placement. The relay would control the flow of electrons and either source voltage to the contact or drain voltage from the contact.