12V Feed

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dirtychinchilla

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Hey guys,

I need to take a 12V feed off somewhere other than the cigarette lighter in my car to rig up a USB port for my iPhone. I have it connected to the cigarette lighter currently, and because the lighter socket has a light connected to it, when you turn on the interior lights it turns off the charger...go figure!! So, where else can I get the feed from? Or should I just take it from the battery and then step it down somehow...if so, how would I step it down to 12V?

Thanks in advance,

dirtychinchilla
 
dirtychinchilla said:
Hey guys,

I need to take a 12V feed off somewhere other than the cigarette lighter in my car to rig up a USB port for my iPhone. I have it connected to the cigarette lighter currently, and because the lighter socket has a light connected to it, when you turn on the interior lights it turns off the charger...go figure!! So, where else can I get the feed from? Or should I just take it from the battery and then step it down somehow...if so, how would I step it down to 12V?

Thanks in advance,

dirtychinchilla
Click to expand...

I managed to get a permanent live from my ciggy lighter...
 
Weird, how did you manage that? I don't know whether I've just hooked up to the wrong terminal as there is a 3 way connector attached to the cig lighter, so perhaps two positive feeds? One being the light and the other being the actual lighter?
 
dirtychinchilla said:
Weird, how did you manage that? I don't know whether I've just hooked up to the wrong terminal as there is a 3 way connector attached to the cig lighter, so perhaps two positive feeds? One being the light and the other being the actual lighter?
Click to expand...

What year is your car? On my 99, there a permanent live feed and a separate dimmer feed if I remember correctly.
 
get it from under the dash

zahubyza.jpg
 
jojo, I'm going to try the other connector, thanks. Have you perchance had an iPhone running of this setup, either of you?

Andrew, that's great. Is the connection that you've used that speaker wire?
 
dirtychinchilla said:
jojo, I'm going to try the other connector, thanks. Have you perchance had an iPhone running of this setup, either of you?

Andrew, that's great. Is the connection that you've used that speaker wire?
Click to expand...

Nope, I run the illumination for my boost gauge off it, and it requires a perm live to remember which colour to stay. I did ask what year your car is, as later cars came with canbus wiring that measures voltage drop instead of on or off.
 
Sorry, I didn't see your question! The car was made in 2003. Could I run the usb port from that connection, though? Presumably I could.

Edit: Greg, I need to get a good constant feed for my iPhone to like the power, so anything that's already being used may not be brilliant.
 
dirtychinchilla said:
Sorry, I didn't see your question! The car was made in 2003. Could I run the usb port from that connection, though? Presumably I could.

Edit: Greg, I need to get a good constant feed for my iPhone to like the power, so anything that's already being used may not be brilliant.
Click to expand...

2003 is quite late, I'm guessing it's highly likely you have canbus on your car, but I'm not 100% sure.
 
Image

You could use one of these to plug into an existing circuit. Original fuse goes into one of the sockets, new fuse in the other. Pick something that operates the way you want your new feed to work, ie on permanently (cigar lighter in your car), first click (radio maybe) or ignition on (heated rear screen, towbar assembly). Only suggestions, your wiring might be different from mine.
 
Hmm that's food for thought, thank you very much. Not entirely sure I understand what to do with it but the heat is getting to me today!

Does anyone know whether there are any unused grommets from the engine bay into the car? I'm thinking that battery wired would be best, but we had a lot of trouble getting a connection through for the amplifier and I can't say I fancy doing that again through the same grommet.
 
You could go the battery route but the fused tap connector is an absolute doddle and will save you going through the bulkhead. Take out the fuse for the radio, plug one of these in, original fuse in the bottom slot, new fuse in the top, connect the live wire of your usb adaptor to the wire on the tap, the other wire to an earth somewhere behind the dash and you are good to go.

PS are you sure it's a usb though as opposed to a charger, I've never heard of connecting a usb direct to 12v - I could well be wrong though
 
Last edited:
Lots of info above, if you are not sure it may be best to get a auto electrician to run a supply for you?

Mark
 
Stevie, thank you very much for the clear description. I'll attempt exactly what you've said; I've ordered the fuse tap and am happy to give it a go. I must admit, the single wire coming from it confused me, but the common return makes sense now.

I have this USB socket Double USB Panel Mount Accessory Charger Socket (12V 5V 1A 2.1A Cigar Dual Twin) | eBay which I hope can take 12V and convert it to 5V, but tbh I'm not sure. I just assumed that the car lighter connection was 12V so this would need to connect to 12V also.
 
No probs, that usb charger looks as if it should work. Just remember that if you use the radio fuse the charger will only be live when the radio would be, ie at first click. IMO that would be best as you can't accidentally flatten the battery, if you need a permanent live just select another fuse.
It might also be an idea to pick up a cheap circuit tester, looks like a small screwdriver with a bulb in it attached to a wire, useful for finding a suitable earth and also checking your new feed is live.
 
Oh yeah, that's a good point. Being connected to the radio is fine; I mainly need it because playing through my phone via BT is draining my battery, and using the sat nav. I'll have a look at other fuses too, though. I've also ordered a circuit tester, cheers :)
 
OK well after all this interesting discussion, I switched one of the wires to a different terminal on the connection to the cigarette lighter and lighting ring, and used a proper iPhone cable, the charger now works perfectly! Thanks all for your input.
 
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