Hello! Log in or Register   |  Help  |  Donate  |  Buy Shirts See all banner ads | Advertise on TheSamba.com  
TheSamba.com
 
6 or 12 volt switches in my buggy?
Forum Index -> Kit Car/Fiberglass Buggy/356 Replica Share: Facebook Twitter
Reply to topic
Print View
Quick sort: Show newest posts on top | Show oldest posts on top View previous topic :: View next topic  
Author Message
62kellison
Samba Member


Joined: March 28, 2018
Posts: 513
Location: mass
62kellison is offline 

PostPosted: Thu May 31, 2018 1:23 pm    Post subject: 6 or 12 volt switches in my buggy? Reply with quote

guys a have a 62 frame it was a 6 volt system.nothing was hooked up completely,don't know if dune buggy ever ran.i put a 12 volt motor/ system/Empi harness in.question is, can I use the headlight/parking light pull out switch that was in the buggy already on my 12 volt system?.it has a white knob,it has prongs on the back labeled with 57,58,30,56,58.I believe its a like 1958 to maybe 1967? switch.can I use this with my 12 volt harness?.and there is a 3 prong dimmer/highbeam switch on the floor.can that also be used with 12 volts?.thanks.
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
MrGoodtunes
Samba Member


Joined: May 14, 2012
Posts: 848
Location: South Florida
MrGoodtunes is offline 

PostPosted: Thu May 31, 2018 2:16 pm    Post subject: Re: 6 or 12 volt switches in my buggy? Reply with quote

@62kellison - Your 6 volt headlight switch and dimmer switch will work just fine with your 12 volt system. What matters most is current, i.e. amperage. A 12 volt headlight will draw half the amps that a 6 volt headlight of the same wattage. My buggy has 1986 Honda CRX headlights with halogen bulbs, and they draw a bit more current than the old seal'd beam type. But on high beam, they draw quite a bit more, being 65 watts vs low beam at 35 watts, resulting in my headlight switch (from 12v stock bug) getting kinda warm when driving for hours at night with brights.
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
62kellison
Samba Member


Joined: March 28, 2018
Posts: 513
Location: mass
62kellison is offline 

PostPosted: Thu May 31, 2018 2:25 pm    Post subject: Re: 6 or 12 volt switches in my buggy? Reply with quote

thanks for the info...
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
dustymojave
Samba Member


Joined: January 07, 2007
Posts: 5802
Location: Lake LA, Mojave Desert, SoCal
dustymojave is offline 

PostPosted: Sat Jun 02, 2018 4:41 pm    Post subject: Re: 6 or 12 volt switches in my buggy? Reply with quote

What truly matters in whether the switch can handle the load is not Amps, but WATTS. Amps x Volts = Watts. That is the true measure of current flow.
_________________
Richard
Offroading VW based cars since 1965
Tech Inspection 1963 - 2012 SCCA/SCORE/HDRA/MORE/MDR +
Retired from building Bajas, Fiberglass Buggies and Rails in the Mojave Desert. Also Sprints & Midgets, Dry Lakes, Road Race cars. All types New and Vintage
SoCalBajas Member
Kicked Cancer's A$$...1st and 2nd round...Fight ain't over yet.
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
MrGoodtunes
Samba Member


Joined: May 14, 2012
Posts: 848
Location: South Florida
MrGoodtunes is offline 

PostPosted: Sat Jun 02, 2018 6:15 pm    Post subject: Re: 6 or 12 volt switches in my buggy? Reply with quote

dustymojave wrote:
... Amps x Volts = Watts ...

Very correct.

dustymojave wrote:
... Watts. That is the true measure of current flow.


Actually, Watts measure POWER; Amps measure current flow.

When a switch is ON, there's theoretically no voltage drop across its terminals (meaning no power dissipated). However, in reality there's always a little resistance; hence a tiny voltage drop (meaning some power dissipated, as heat).

From Wikipedia: Ohm's law states that the current through a conductor between two points is directly proportional to the voltage across the two points.

So, amps thru our headlight switch is directly proportional to the tiny voltage drop across the switch's terminals. We can now write that Amperage 'is proportional to' Voltage as:

A ~ V

To make the proportion into an equation, we need a so-called 'constant of proportionality' i.e.:

A = cV

Solving this for V:

V = A / c

And substituting this into the power equation:

P = V*A

gives:

P = (A/c)*A = A^2 / c

So, power is Amperage SQUARED divided by a constant.

Bottom line...

You (dustymojave) and I are both right. Power IS what matters; and, it is directly proportional to the square of Amperage.
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
dustymojave
Samba Member


Joined: January 07, 2007
Posts: 5802
Location: Lake LA, Mojave Desert, SoCal
dustymojave is offline 

PostPosted: Sat Jun 02, 2018 7:47 pm    Post subject: Re: 6 or 12 volt switches in my buggy? Reply with quote

Just to clarify that we ARE saying the same thing (but I was trying to keep it simple).

dustymojave wrote:
What truly matters in whether the switch can handle the load is not Amps, but WATTS. Amps x Volts = Watts. That is the true measure of current flow.




MrGoodtunes wrote:
And substituting this into the power equation:

P = V*A


In MrGoodtunes post, he was leaving out the simple statement that in his equation and mine:
P (for "Power") is commonly expressed as "Watts".

So...Yep. We're saying the same thing. The switch doesn't much care if the W is high Volts X Low Amps, or if it's low Volts X High Amps. As long as the total watts is within the capacity of the switch.

For instance, the toggle switches that have been in the dash of my 1958 Baja Bug for about 450,000 miles and 45 years are rated at 10A/250V. That works out to 2,500 Watts. So at 12V (or more accurately about 14V as a max voltage for my 12Volt system):

2500W/14V = 178.6Amps

So my switches are rated to handle over 175 Amps in my 12 Volt system. The same switch in a 6V system would take

2500W/7V = 357.1Amps Exclamation

Both my headlights together on high beam draw less than 6 amps at 12V. That switch is VERY capable of handling that flow.

The stock VW/Bosch headlight switches are rated similar to those toggle switches. Bosch doesn't specify the rating on the housing as is done on my multi-purpose industrial/aircraft toggle switches. That's only because they're for a specific application, not for general purpose. Not only can you use 6V switches in a 12V system, or vice-versa, you also don't need any silly relays that would just over-complicate things and multiply cost.
_________________
Richard
Offroading VW based cars since 1965
Tech Inspection 1963 - 2012 SCCA/SCORE/HDRA/MORE/MDR +
Retired from building Bajas, Fiberglass Buggies and Rails in the Mojave Desert. Also Sprints & Midgets, Dry Lakes, Road Race cars. All types New and Vintage
SoCalBajas Member
Kicked Cancer's A$$...1st and 2nd round...Fight ain't over yet.
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
62kellison
Samba Member


Joined: March 28, 2018
Posts: 513
Location: mass
62kellison is offline 

PostPosted: Mon Jun 04, 2018 3:10 pm    Post subject: Re: 6 or 12 volt switches in my buggy? Reply with quote

got it.thanks guys!!
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
EVfun
Samba Member


Joined: April 01, 2012
Posts: 5433
Location: Seattle
EVfun is offline 

PostPosted: Mon Jun 04, 2018 4:31 pm    Post subject: Re: 6 or 12 volt switches in my buggy? Reply with quote

dustymojave wrote:
So...Yep. We're saying the same thing. The switch doesn't much care if the W is high Volts X Low Amps, or if it's low Volts X High Amps. As long as the total watts is within the capacity of the switch.

For instance, the toggle switches that have been in the dash of my 1958 Baja Bug for about 450,000 miles and 45 years are rated at 10A/250V. That works out to 2,500 Watts. So at 12V (or more accurately about 14V as a max voltage for my 12Volt system):

2500W/14V = 178.6Amps

So my switches are rated to handle over 175 Amps in my 12 Volt system. The same switch in a 6V system would take

2500W/7V = 357.1Amps Exclamation

That is so wrong I don't know if I should laugh or cry. Switches don't care about watts of load, only the amps the contacts will carry and the voltage they will be asked to stop when turned off. Both are important for different reasons.

The voltage rating of a switch is how much voltage it can safely shut off without a risk it arcs over and continues to allow current to flow. You cannot use an AC awitch rating to determine the DC voltage it can handle (though as an estimate the DC rating will be about 20% of the AC voltage rating.) You can freely use a switch under its voltage rating, but not over it.

The current rating is all about the heating and failure of the contacts sooner than designed for. If you have a very sensitive ohm meter (not your average digital multimeter) you can measure switch contact resistance. Amps squared times resistance equals watts of heat being created in the switch while carrying that current. Because amps is squared in this equation yoy can see that if the switch carries half the amps it is rated for it will only make a quarter of the heat, and that system voltage is not a part of the equation. It is safe to use a switch for less than the rated amps, but not more.

12 volt auto systems almost always use less current because power is measured in watts (volts times amps equals watts.) A single 35 watt 6 volt headlight draws about 5 amps (car bulbs are designed for charging voltage, about 7 for a 6 volt car and 14 for a 12 volt car.) A single 55 watt 12 volt headlight draws about 4 amps.

**Edited the last word of my post. Thank you to the user who PMed me and pointed out my error!
_________________
Wildthings wrote:
As a general rule, cheap parts are the most expensive parts you can buy.
Back to top
View user's profile Send private message Gallery Classifieds Feedback
Dale M.
Samba Member


Joined: April 12, 2006
Posts: 20360
Location: Just a tiny bit west of Yosemite Valley
Dale M. is offline 

PostPosted: Fri Jun 08, 2018 8:16 am    Post subject: Re: 6 or 12 volt switches in my buggy? Reply with quote

The irony of all this discussion (car related) ... Switches, fuses, relays, alternators, generators and wire are all referenced to as AMPS ratings.... About only thing mentioned in WATTS is light bulbs and power required for radio (not specifically power output)...

Dale
_________________
“Fear The Government That Wants To Take Your Guns" - Thomas Jefferson.

"Kellison Sand Piper Roadster" For Street & Show.
"Joe Pody Sandrover" Buggy with 2180 for Autocross (Sold)
============================================================
All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ...
Back to top
View user's profile Send private message Gallery Classifieds Feedback
Display posts from previous:   
Reply to topic    Forum Index -> Kit Car/Fiberglass Buggy/356 Replica All times are Mountain Standard Time/Pacific Daylight Savings Time
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum

About | Help! | Advertise | Donate | Premium Membership | Privacy/Terms of Use | Contact Us | Site Map
Copyright © 1996-2023, Everett Barnes. All Rights Reserved.
Not affiliated with or sponsored by Volkswagen of America | Forum powered by phpBB
Links to eBay or other vendor sites may be affiliate links where the site receives compensation.