amp and fridge??

[Haydz]

hey guys ive got a small fridge that i wanted to run in my boot just wondering. could i connect it to the positive and ground on my amp?
or would i have to use something different? thanks.

[r_i_d_a_h]

say what? a small fridge? is it one of those mini 12 volt?

[kopper69]

Can you have a look on the fridge itself, there should be a small placard that tells you the power requirements. You are looking for a reading in either watts or amps. If your not sure just write down exactly what you see on the placard.

Ideally you should run a new power supply down there that is fused with a fuse that suits the fridges power requirements.

There is no reason why you cant use the amps power supply, but you need to be very careful on wiring it. Maybe use a distribution block. You will also need to fuse the power from the distribution block to the fridge with an appropriate fuse for the fridge. If the fridge uses a cigarette lighter plug, I would put a socket there so you can just plug it in when you put the fridge in the car.

Anyway let us know the power requirements and we can go from there.

[Haydz]

well i found the fridge in my garage and it just had two cords coming out of it. so i got a ciggy lighter plug i had and wired it up to that with a 20 amp car fuse and it worked from the cigarette lighter. so atm i can plug it into the ciggy lighter but i use it for other things.(gps.phone.) and i was thinking i could wire it up to work from my amp. cheers guys. would that mean the fridge is on all the time or it would turn off when the stereo turns off?

[Haydz]

4 amps at 12 volt dc. and it says use 12 volt only..

[kopper69]

Power to the amp is available all the time, so the fridge would be on all the time. To turn the amp on and off, the amp uses a separate wire called a remote wire.

If you only want the fridge on when the car is on your best bet is to tap onto the accessory circuit, which only comes on when the car is on.

If the fridge doesnt have any info on its power usage I would put a 10A fuse in and see how she goes. Your better off going lower and increasing if it blows than going too high. That might give you an idea of how much power it is using.

[kopper69]

4 amps at 12 volt dc. and it says use 12 volt only..

4A. I would put a 5A fuse in. If you do blow that, put a 10A in. 20A is too high. I would connect a wire from the cigarette lighter in the car, run it into the boot and put a cigarette socket in there. Your existing fuse and relay should easily take the power of the fridge and anything else you might plug into the existing cigarette lighter.

[Haydz]

is there any near the boot on a vr/vs that i could connect to ?>

[commsirac]

These small fridges are usually quite well insulated and even in 30+ conditions may only operate at 1/4 cycle or so.....ie only draw 4 amps for 1/4 of the time.

Depends what you use the fridge for.....camping holiday? Its going to be a bit inconvenient if you have to have the ign turned to accessories while the car is parked for a few hours.....as well as running the problem of having other accessories inadvertently left on in the car. Id be wiring it direct to the amp, given youve probably got twice as much wire going to your amp now than you really need? Of course its up to you to remember youve got it running.

As suggested, have a cig lighter socket for the boot, running of the amp. It will come in handy for lots of other stuff too.......and might be a tad more convenient then using the one inside the car. In one of my cars I have one of these and a hot connector post for connecting up accessories (things with alligator clips that normally attach to the battery).....spotlights, air compressors etc....all running of the wire that powers the amp in the boot.

Im not sure if the standard trailer wire strip that is in there has a +12V output or not........check that out

[Haydz]

ok cheers guys so where will i get a cigarette lighter socket from? dick smith? jaycar? thanks for all the help.

[commsirac]

Ah, was going to mention that, the ones that are supplied by places like dick smith are typically fairly 'crappy' with flimsy terminals for which to solder the connections onto.

IMO, better alternative to get a socket out of an old car where at least the wiring and connectors was up to the ability of handling the current that a cigarette lighter would draw. Only problem there is it wont be all insulated etc, but could make a little wooden box for it etc. Go for a walk around a wrecker and see what you find, ones that are contained within the ashtray could be useful.

[Haydz]

thanks ill do that next time i go to the wreckers.

[kopper69]

Ive recently used these and havent had any trouble with them:

DSE Cigarette Lighter - Y Splitter / Double Adaptor (P1691) - Dick Smith Electronics - Australia. Search, Research, Buy Online.

You just cut the socket off. The good part is that you also have a spare plug and socket if you need them. Another option may be these:

Cig Plug Extension lead (P1681) - Dick Smith Electronics - Australia. Search, Research, Buy Online.

The come with a cover which may make it a bit neater in the boot. Comes with 2.8m of wire, although if it isnt thick enough to carry the current it wouldnt be worth using as you would have to rewire it anyway.

They are insulated too.

[Haydz]

thanks mate i like the firsr idea. what sort of cable should i buy could i just use some thick speaker cable? like the one to run a sub?

[Haydz]

also could i get a small switch so i have the option of turning it off also? are they hard to wire up?? thanks

[kopper69]

The fridge uses 4A, which isnt all that much. Have a look at the wire when youre at dick smith. They are pretty good as they have rated most of the wire they sell (ie 10A, 20A etc). I would recommend this stuff:

Auto Heavy Duty Power Cable (W2027) - Dick Smith Electronics - Australia. Search, Research, Buy Online.

Its rated for up to 15A, which will give you more than enough current carrying capability for your fridge which only requires 4A. Its insulated nicely too and both wires are run neatly together.

If you do have any left over wire, from a sub or whatever, that might be long enough let us know how thick it is and you might be lucky. The stuff for your sub (from the amp to the sub) might do it.

Using a switch is a little different. For a switch, 4A is a lot of power. Again dicky smith is pretty good as he has labelled the current rating of most switches.

If youre happy to pay $10 you can get this little beauty:

KT Missile Toggle Switch SPST (P7691) - Dick Smith Electronics - Australia. Search, Research, Buy Online.

Rated at a pretty impressive 20A. Supercheap and autobarn sell these too I think, so you can shop around to try and save some $, but I think they are all about that price.

Dick smith does have a pretty good range, so choose something you like. Just watch the current. If you find a switch, but it is only rated for 2A or something like that under about 6A, you will have to use a relay. A relay is a bit harder to wire up and is another thing to go wrong. Plus it will cost you and extra couple of $. Find a switch that will take the current and wiring up will be a whole lot easier. Wiring the switch will be one of the easiest things to do. You just treat it like a fuse: Cut the wire where you want it, one side of the wire to one side of the switch and the other side of the wire to the other side of the switch.

[commsirac]

Not sure what you are planning to do, however, one weakness or long runs from the cigarette lighter is voltage drop, especially if you are using the lighter socket as the return path. a 3m extension cable is really 6m of wire, even at 4A the voltage drop will be significant.

Suggest only the hot wire(12V) to the boot and earthing the outer connector of the socket in the boot.

[kopper69]

commsirac you are way off mate. Voltage drop is not even a consideration. The cable has a resistance of 10.1m ohms/meter. For 6 meters (3m there and 3m back) of cable the resistance is a mere 0.06 ohms. The current is 4A, so using ohms law we can calculate the voltage drop:

V=IR
voltage drop (V)= 4 x 0.06 ohms
voltage drop = 0.25V

That is nothing. Definitely not significant.

[commsirac]

commsirac you are way off mate. Voltage drop is not even a consideration. The cable has a resistance of 10.1m ohms/meter.

I must have missed that 15 gauge cable was going to be used, ?


Using a cable rated for 5-7A which would be quite adequate for just the fridge would see the figure you have quoted increase by factor 3, significant. Voltage drop would be a consideration, overcome by reducing the length of the wire.

Its also a consideration to realise that even the cigarette lighter itself is probably a couple of metres of wire away from the battery and the total voltage drop through the various connections(do cig lighters have relays now?) +extension leads will have an impact when the engine is off.