12v socket fed from an ignition live - Ford Fiesta

azibux1

azibux1

azibux1

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Hi all,

I'm looking at installing a 12v socket that is fed from an ignition live, rather than the original socket which is a constant live.

What's the best way to do this?

I've read that the only way to do this, without cutting into original cabling, is to get an "add a circuit" piggy back fuse and use it to replace the fuse of an 'item' that is only on when the ignition is on?

Would it then be okay to still run that original item and the 12v socket from the same feed?

Any help would be appreciated please

Thanks in advance :)
 
That would depend on what you're taking the ignition live feed from and given you can draw a lot from a 12v feed I wouldn't be happy with that. Remember the wiring may potentially have to take the current from the 12V at the same time as whatever you're piggy backing from.

The way I do it is to find an ignition live, usually from the radio, and splice that (which you could do with a piggy back fuse I guess), but plug it into a relay so the relay switches on with the ignition live. Then run a fused wire directly from the battery, through the relay, to the 12V socket and back to the battery earth.

Safest way IMO.
 
miniyazz said:
That would depend on what you're taking the ignition live feed from and given you can draw a lot from a 12v feed I wouldn't be happy with that. Remember the wiring may potentially have to take the current from the 12V at the same time as whatever you're piggy backing from.

The way I do it is to find an ignition live, usually from the radio, and splice that (which you could do with a piggy back fuse I guess), but plug it into a relay so the relay switches on with the ignition live. Then run a fused wire directly from the battery, through the relay, to the 12V socket and back to the battery earth.

Safest way IMO.
Click to expand...

Hmm I see, never really (majorly) 'added' to my cars electrics before.

Does this relay have to go in the box with the rest of the relays? My guess is no, I've never wired a relay before so might need to look into how that is done first

The rest of your explanation does make sense though, thanks :)
 
Used an "add a circuit" to wire in a phone charger behind the dash in my S2000.
Works well and had no issues so far :)
 
azibux1 said:
Hmm I see, never really (majorly) 'added' to my cars electrics before.

Does this relay have to go in the box with the rest of the relays? My guess is no, I've never wired a relay before so might need to look into how that is done first

The rest of your explanation does make sense though, thanks :)
Click to expand...

No, it can be wherever you want it. In the Golf I hid it in the top of the glove box. Relays are simple enough, there's a hundred and one explanations online I'm sure. Two things I guess: make sure you get a relay rated to a decent current (20A minimum I would guess, but depends what you intend to plug in), and don't get cheap wire. I bought cheap wire once and it couldn't take any meaningful amount of current and melted the insulation at around 10A :p
Also make sure you have a roll of insulating tape, it'll come in useful.

HouR said:
Used an "add a circuit" to wire in a phone charger behind the dash in my S2000.
Works well and had no issues so far :)
Click to expand...

I guess at most that'll draw about an amp hence almost certainly fine :)
 
Thanks guys

All I am planning on using it for is a dashcam, which I'm told also only draws around 1A

It's been suggested that I'll likely have a 'blank' bay in my fusebox, for an optional extra that I do not have fitted in my car, but it will be ignition live in the 'prep' for if I had the extra fitted

Going to see if I have one of those tomorrow and use that with a piggyback fuse, if not then I'll probably have to take the relay route :)
 
Yeah trying to find a spare fuse slot in the fusebox and piggyback fusing that is a good call.

When I had my MK7 Fiesta I piggyback fused a second lighter socket off the airbag fuse. I was only using mine for my dashcam which as you mentioned draws very little current. Had that setup running for months with no problems at all with the socket and the plug tucked away down behind the glove box. There's conveniently a nice bit of metal in there with a bolt which makes a great ground point also.

I obviously wouldn't trust it with something more substantial like a power inverter however, but a standard USB type power supply shouldn't be an issue at all.
 
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Airbag fuse, brave man :eek:

I prefer non-essential items like radios, not least because if you take an airbag fuse out you're liable to be left with an airbag warning light on the dash that won't go away (or deploy the airbags) until you take it to a dealer to reset it!
 
Well yes on reflection it wasn't the best choice ;) I'm not recommending that one is used by the way and I wouldn't use it again. The Fiesta didn't care though, when the fuse was pulled you of course get the warning light on the dash but putting it back in with the fuse tap in also was fine in the months I had it anyway.

Definitely try to find an empty fuse slot that may still be powered, there's bound to be one somewhere.
 
Thanks all

Yeah I think the empty fuse slot idea sounds best, will try that out

So if I was to get a piggy back fuse, not to piggy back anything, just to get a nice solid connection out of the blank fuse location, and to fuse the dashcam, which amp should I get? There doesn't seem to be much choice when it comes to small fuses for the 'add a circuit' fuses, all I can see is 20 amp :O lol
 
Oops only just realised how the piggy back actually works, didn't realise you insert a fuse into the slot, I assumed it was built in

Right so it says 20amp, I assume it means it can handle up to 20 amp? You can put a 5 amp mini blade fuse into it if you want?
 
Yeah they usually have two fuse slots on - one for the original fuse it's replacing which if you're slotting into an empty slot will of course remain blank. The other you can put what you need in so just put a 5amp in it and you're good to go.
 
I'm looking at doing this too to wire a bluetooth dongle in for my HU (need a permanent and a ignition live). Where did you get your piggyback from?
 
I guess I can mention it since they aren't a competitor to OcUK for this product

It was from amazon. Search Amazon for "add a circuit fuse"
 
Recently I've picked up some bits online which is basically a 12v to 5v stepdown with USB socket. I've found these don't power my phone sufficiently compared to a decent USB plug in adapter that plug into a 12v socket.

I've got a free spade connector that is wired into an inline fuse, rather than into a spare fuse slot.
 
Scottland said:
Recently I've picked up some bits online which is basically a 12v to 5v stepdown with USB socket. I've found these don't power my phone sufficiently compared to a decent USB plug in adapter that plug into a 12v socket.

I've got a free spade connector that is wired into an inline fuse, rather than into a spare fuse slot.
Click to expand...

Where was this free spade connector? Also in your fuse box somewhere?

ci_newman said:
Ah I see, it looked to me that you needed another "male" part to plug into that crimp.
Click to expand...

Hmm that's just my guess. If it was more 'flat' I would expect it to be a spade terminal that would need a male plugging into it, but I think it is just a bullet style one that needs crimping down. Will let you know when mine arrives
 
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