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January 2013 Randy’s Electrical Corner

154 1301 03 January 2013 Randys Electrical Corner 12 Volt Wiring Diagram
Randy | Photographer
Posted January 1, 2013


Hey guys, it’s me. You guys have sent in a few questions about wiring up batteries for 12 volts or 24 volts, and I started to write about it. Then I realized that I had already done it. I went back and found it. I also remembered following Kenny around and the college incident after re-reading it. Anyway, I wanted to get back to the basics, and since I was getting some questions, I figured this was good way to do it. So here’s how to wire up your speakers or batteries in series or parallel.

In some college some-where there is a professor droning on and on about series and parallel and even series/parallel circuits. I was following Kenny around and picking on him and accidentally ended up in the back of one of these classes. I don’t really remember much of it though because I fell asleep and woke up in the middle of some kind of “art” class, if you know what I mean.

Anyway, you might be asking yourself, “Self, why do I care if something is in series or in parallel?” Well, I’m glad you asked—you see aside from being armed with more knowledge than your buddy on the bar stool next to you, it is handy to know the difference and how to hook each one up. You can hook anything up in series or parallel, from lights to batteries to speakers, the trick is to know why you’d wanna hook it up one way or the other.

Take speakers for example. If you hook them up in series, you will end up with less sound coming out because the resistance the stereo sees is greater. However, if you hook them up in parallel, while it will be louder, you run the risk of shorting out your radio. Just like the turn signal flasher, the radio wants to see some resistance to function right. How much resistance depends on the unit you are using.

Take lights for another example; if you wire lights up in series and one bulb goes out, all the lights on that circuit will go out (think of old-school Christmas lights). So wiring them up in parallel is a good way to go. Some Jeeps have their turn signal lights wired in a series/parallel setup which allows the front signal to blink, and then the side signal in an alternating pattern.

Now, if you were to wire up batteries in series, you end up adding voltage. Many military vehicles have two standard 12-volt batteries wired in series to provide 24 volts to the radio equipment. However, if you wire up two 12-volt batteries in parallel, you end up adding the rated amp/hour ratings like in many diesel trucks that need more cranking power to get started.

It sounds complicated, but it really isn’t. Just check the pictures below and you’ll come away with a new understanding of a pretty simple wiring idea and be able to apply it down the road.