I have having a mental blank spot.


If I have two batteries that are 12 volts each how do I wire them to have 24 volts?

Series, ie: positive to negative.

Nick

Quoted: Series, ie: positive to negative. Nick

That won't reduse current will it?

Sgtar15

In series will give you 24 VDC from the + on the first to the - on the second...

Parallel will double your current capasity but only 12 volts.

Quoted: Quoted: Series, ie: positive to negative. Nick That won't reduse current will it? Sgtar15

If you go from 12v to 24v with the same load, ie resistance, your current should increase. The way to calculate that is: V=I*R where V=voltage, I=current, and R=resistance. As you can see by the equation if you increase the voltage and keep resistance constant, current will have to increase.

  ------------( - )  Battery 1  ( + ) ------------- ( - )  Battery 2  ( + )--------



  -----------------------------( - )  Load   ( + )-----------------------------




How ya like that  I'm an electrician, btw.....  Whatcha trying to do ?

Quoted:   ------------( - )  Battery 1  ( + ) ------------- ( - )  Battery 2  ( + )--------  |                                                                                                                          |  |                                                                                                                          |  |                                                                                                                          |  |                                                                                                                          |   -----------------------------( - )  Load   ( + )----------------------------- How ya like that  I'm an electrician, btw.....  Whatcha trying to do ?

Nice pic...I was trying to draw that earier myslef.

No...can you show me how I would add more driving lights on my truck so that they all operate off of one switch and how I can do it with two sets with each set on its own switch.

Sgtar15

Quoted: Quoted:   ------------( - )  Battery 1  ( + ) ------------- ( - )  Battery 2  ( + )--------   -----------------------------( - )  Load   ( + )----------------------------- How ya like that  I'm an electrician, btw.....  Whatcha trying to do ? Nice pic...I was trying to draw that earier myslef. No...can you show me how I would add more driving lights on my truck so that they all operate off of one switch and how I can do it with two sets with each set on its own switch. Sgtar15

Sorry, stupid text didn't post how I intended, but I think you get the idea....


You'd probably need a relay, to control more than two lights via one switch....  

The current drawn by that many lights, would get up there, and melt your ordinary type switches...

You never wire lights in series, (like above)  because :

1.  when one burns out, ALL go out... like old Xmas lights

2.  you're doubling the amount of current running through said wires, which is a no no,,,, heat, burning wires, etc, etc.  

you want to wire them in parallel....... all ( + ) together,  & all  ( - ) together

Then run those back to the relay, that should be fed to the battery directly, to provide the necessary current.....

No stock auto wiring will handle this kind of current.......

For say, a 55W halogen lamp, EACH lamp draws 4.6 amps..... soooo, with 4 lamps, you're looking at almost 20 amps of current.......

You'll fry most ordinary switches / wiring in short order.. I know you can buy 20A rated switches at the auto parts store, but trust me... they are NOT going to last, without you spending some money on a high-quality switch....... those 5 dollar pieces of taiwan shit wont cut it.....  seen many catch on fire, when dumb friends did this.

The relay, fed off the battery, being controlled by a switch, is the correct way to do this.....

If you get stuck, I may be able to find a diagram online somewhere to show you how to do this.

Or else, I'll just DRAW one and scan it in for ya  

Hope that helps some

JB

Quoted: Quoted: Quoted: Series, ie: positive to negative. Nick That won't reduse current will it? Sgtar15 If you go from 12v to 24v with the same load, ie resistance, your current should increase. The way to calculate that is: V=I*R where V=voltage, I=current, and R=resistance. As you can see by the equation if you increase the voltage and keep resistance constant, current will have to increase.

Along with push-ups, I like Physics too!!

A 12 batt. is several smaller cells in series. You are just continuing the process.

So let me get this straight.  Series keeps voltage the same but increases current.

Parrallel doubles voltage and reduses current.

Okay...got that.

As far as wire ratings if I double the rating I need mathamatically I will be okay correct?  and yes still use a relay

SGatr15

Quoted: So let me get this straight.  Series keeps voltage the same but increases current. Parrallel doubles voltage and reduses current. Okay...got that. As far as wire ratings if I double the rating I need mathamatically I will be okay correct?  and yes still use a relay SGatr15

No, doesn't work that way........

IM me, I'll get you squared away, and you wont get confused by so many replies here.....

JB

Quoted: So let me get this straight.  Series keeps voltage the same but increases current. Parrallel doubles voltage and reduses current. Okay...got that. As far as wire ratings if I double the rating I need mathamatically I will be okay correct?  and yes still use a relay SGatr15

Series increases voltage, but has the potential to increase current, given a fixed load. If you increase the resistance or load then it will vary. V=IR
Parallel keeps voltage constant, but has the potential to provide more current.

Then there is the whole if you're going to wire more lights or whatever in series or parallel. Gets to be a mess.