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12v output or 24v output???

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Farmaller48

New Member
Likely a silly question for the rest of you, but something I need to know and don't know now. Working with a 12 volt automotive system, if you were to tie into EACH of the two brake light power supplies (right side and left side - perhaps about 6 inches back from the actual brake light assembly), then take the ends of the two new wires that you tied into each of the two brake light supply wires and put the bare ends of them together, if you measured the voltage output when you press the brake, would you get a 12v reading or a 24v reading? I suspect the correct answer is that you would only get a 12 volt reading.
 

Dr_Doggy

Well-Known Member
break lights are usually in parallel, which is when the current(amps) split to each light..

putting your lights in series the 12volts will divide between each light, so there will be 6v across each
 

ronsimpson

Well-Known Member
Most Helpful Member
The brake wire for the right side will measure 12V or 0V depending of the lights are on or off.
Wiring the two sides together, (right & left) will get you the same 12V or 0V.
I might not understand the question.
 

audioguru

Well-Known Member
Most Helpful Member
The brake lights on a car have only a single power supply, the 12V battery, not two power supplies. The left and right brake lights are connected together so they both turn on at the same time by the brake light switch.
If both brake lights are turned on and you connect wires to the 12V side of each bulb then obviously the voltage between the two wires is NOTHING. If you tie the two wires together then when the brakes are on the connection of the wires is obviously 12V.
How on earth (or on the moon?) can you get 24V from a 12V system?????
 

ronsimpson

Well-Known Member
Most Helpful Member
How on earth (or on the moon?) can you get 24V from a 12V system?????
Real simple:
You get 12V on the right side. AND You have 12V on the left side. So when you add the left and right together....12+12=24.
Can you tell I have been doing month end taxes.
 

audioguru

Well-Known Member
Most Helpful Member
When I do my taxes I show the government that my income and expenses are the same so I pay no taxes. Hey, I am retired, my government pays me.
 

dr pepper

Well-Known Member
Most Helpful Member
As said, not reccomended on a later vehicle, these days they have load sensing to detect a blown bulb.
 

audioguru

Well-Known Member
Most Helpful Member
Old fashioned incandescent light bulbs? They were designed to blow out. That is why LEDs are used now.
 
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