help with wiring cigarette socket for mobile shenanigans please?

[loudassassin]

I've got some wire to install my radio with, its come from an audio amp installation. I dont plan on using any burners/amps etc and will only be using the cb radios power. The radio has a 10amp inline fuse on the positive side as factory fitted. But i want some overkill to make it easier to adapt at a later date if i need to.

I want to wire in a 10A or 15A cigarette lighter socket so that i can plug the radio in quickly, and use a solar charger that has a factory fitted cigy lighter style plug, to top the battery up.

The wires i have at the moment are:
thick red is 8awg with a 60A agu fuse
thinner red is 10awg
some black 10awg with a blade type fuse holder

Id like to know if it would be better to ground the negative onto the vehicle or direct to the battery?
Would i be better investing in some 8awg for the negative? (as i have 10awg slightly thinner stuff at the moment).
Also if having a fuse on the negative side would be a problem or just a bit of extra safety?

all help is much appreciated thanks

heres a dodgey diagram of my plan for your enjoyment


Thanks.

[Tigersaw]

The fused in the -ve side is a necessary if you run a cable direct to battery.
Think about a fault scenario where the earth braid to the engine or chassis goes high resistance, you could then be in a situation where your -ve cable to the radio to ground via the antenna is the least resistance and will draw high current and catch fire.

[ghost123uk]

No advantage to connecting the -ve to the battery, in fact a couple of disadvantages, so just connect it to a suitable bit of bright metal as close to the location of the fag lighter as is convenient. Any of the wires you mention will be suitable to splice into, I would use the thinner ones, they are perfectly suitable for the extra (small) loads you intend to use them for. How do you intend to splice into the existing +ve wire? A 10A fuse at the furthest end of the +ve wire from the socket is a must. There is no need at all to put a fuse in the -ve line (sorry to disagree with you Tigersaw)

The solar panel with the fag lighter plug is a good and versatile way of doing it, but what power panel are you considering? (I have a good reason for asking).

Also, check that your fag lighter sockets stay connected when the engine is off, some do, some don't and mine, (Citroen / Peugeot) used to switch off 30 minutes after the key was removed !!!! = I fixed that "feature"

Source = 40 years of being an electronics engineer and 15 years of wiring up all sorts of stuff on VW camper vans

[loudassassin]

Thanks to you both for your replies.

How do you intend to splice into the existing +ve wire?

I was going to use ring connectors on the battery terminal clamps, and run both cables through the bulkhead firewall down into the passenger footwell area.

The solar panel with the fag lighter plug is a good and versatile way of doing it, but what power panel are you considering? (I have a good reason for asking).

I already have this one streetwize swsol1 1.5a
https://goo.gl/Tq29Db
but it wont work on my existing car ciggy lighter, as it goes off when the ignition is off.

thanks again

[ghost123uk]

Thanks to you both for your replies.

How do you intend to splice into the existing +ve wire?

I was going to use ring connectors on the battery terminal clamps, and run both cables through the bulkhead firewall down into the passenger footwell area.

That's OK, but it might be easier to tap into a permanent live feed off the cabin fuse box. And remember, any bright metal will make a perfectly good earth for the -ve lead, no need to go to the battery, or indeed any further than the nearest bright metal (a self tapper etc) to the new socket.

The solar panel with the fag lighter plug is a good and versatile way of doing it, but what power panel are you considering? (I have a good reason for asking).

I already have this one streetwize swsol1 1.5a
https://goo.gl/Tq29Db
but it wont work on my existing car ciggy lighter, as it goes off when the ignition is off.

OK, really, don't expect much from that panel - I have fitted lots of solar panels to camper vans and the manufactures claims or often wildly optimistic. They say that it "Operates under cloudy conditions" = cobblers. The rated output of 1.5A might be available if it's pointed at a full on sun in mid summer, but my experience (considerable) of those is that on a dull day the output can fall to just 10s of milliamps, literally. If you have a multimeter (I'm sure you have ), set it to an Amp range in excess of 2 Amps and connect it directly across the panels output, with no battery etc connected, and point it at the sky and see what your meter shows (p.s. = no harm will come to your meter, or panel, doing that test with that panel).

[Tim]

Run a 17A cable to the radio with a 15A blow fuse in the positive line straight from the battery to the radio, that way you avoid any RFI from engine, alternator and other wiring plus a cigarette socket/plug connection in the main is very poor, it reduces power flow and can give RFI and all sorts of problems, such as over heating. As for the solar panel, if you're thinking of keeping the battery charge up, connect that straight to the battery as well not via the cigarette lighter socket because you will loose a lot of the power it receives from the sun/light and power it will deliver to the battery through the vehicles wiring. Been there, done that.

[ghost123uk]

We will agree to disagree there then Tim

[loudassassin]

Cheers for all your help on this.

I ran the solar charger on a previous car, its only a trickle, but i suppose every little helps. I've got a multimeter, and if the sun ever shines again, ill definatley give it a test, i'll post results here.

Im a bit scared of messing behind the fuse box and taking a supply from it, so ill probably stick with the main battery method for +ve and get a 10A AGU fuse to replace the 60A. The grounding should'nt prove to much of a problem to get it close to the socket, there should be plenty of places to go in.

I've got a ciggy plug (no springs or fuse inside) wired directly onto the nose and the outer terminal with the radios wires. I've not got the 15A socket yet, but im gonna go this way, i reckon as its more versatile for a phone charger sat/nav etc. If it did start causing problems as Tim mentioned then i could always use a different type of quick connector once the wiring's in place.

[Tim]

I should have mentioned that the cigarette lighter socket in the vehicle will only be good for a maximum of about 8A at best, that will be the wiring rating, this is what may cause over heating that I mentioned especially if the radio will be drawing more Amperage than what the wiring to and through the socket can supply.

[ghost123uk]

Aye but apparently we're only talking about a CB set, say 3 Amps for a legal one (or 5 Amps for a multimode) and only 1.5A for the solar panel. At these current levels there will be no noticeable voltage drop caused by the plug and socket, or the wires. Simple maths.

It will be fine as long as you get a half decent socket and plug and wire it up sensibly and neatly (which I'm sure you have every intention of doing )

[loudassassin]

Aye but apparently we're only talking about a CB set, say 3 Amps for a legal one (or 5 Amps for a multimode) and only 1.5A for the solar panel. At these current levels there will be no noticeable voltage drop caused by the plug and socket, or the wires. Simple maths.

It will be fine as long as you get a half decent socket and plug and wire it up sensibly and neatly (which I'm sure you have every intention of doing )

Yep, Im going to take my time and install it nice and properly, the radio going in according to the manual does 40w max FM and 35w ssb.
Im feeling much more confident now with the advice you guys have given me. So im just waiting for a nice day (and a day off work) to go out and run the wire through the bulkhead and get on with the install.

Thanks for all your help

[loudassassin]

Righteo, an update on my failings.
The going through the bulkhead plan didn't work out, i didn't fancy splitting the large main wiring loom grommet. But i cant see another way in to the cabin, im not going to be drilling it because i don't want to knacker my car if i get it wrong. So the direct to battery plan is foiled for me (for now).

However, Ive since looked at the radio (which is a ss6900n), the instructions mention NOT to replace the 10A fuse, i opened the holder out of curiosity to find a 15A fuse. Its a brand new radio so this was fitted factory end it seems. It claims to do >40w fm >35ssb or something similar (i wont be using burners etc).
So i went onto the old ohms law calculator and did the voltage from 10v up to 15v at 40watts, i don't get amps up to 5A.
After a bit of amateur gymnastics and contortion, i checked the fusebox in the car and my accessories fuses are 20A each for the 2x ciggy lighter sockets. So it looks as if the maths is ok for standard ciggy connection, but think that's going to be a last resort just in case the wiring's not up to it.

Other options i have are, an auto electrician has offered to take a feed from the fuse box for £30, so there's that road to try if the wife lets me have some pocket money from my wages.
Ive got an old spare car battery im trying to charge up at the moment, i can put that in the boot and charge it up every now and then.

the saga continues....

[ghost123uk]

I've been running a very similar radio (AT-6666) from the ciggy socket on my Peugeot for some months now. It works just fine. I used the best quality plug I could find however I checked the voltage drop during transmit and it is completely negligible.

EDIT = By the way, the plug I used did NOT have a fuse inside it like many do. I chose it on purpose because the way the fuse contacts in the fused type is not very secure and could cause voltage drop. I also don't have an in-line fuse because the fuse on the fuse panel is sufficient protection. "Keep it simple"

I did mention further up here, taking a feed from the main line in to the fuse box, but my findings make even that unnecessary.

[loudassassin]

Cheers ghost123uk, I've also gone for a type without an internal fuse but there is a fuse inline on the radio side. I reckon it'll do the trick.