Wiring for fridge

Tony.

The best way to check is get a multimeter and measure the voltage at the fridge when it starts and while it is running. Do this with the engine "off".
If the the fridge works o/k then all is fine.

Regards

Hi Tony,
You can calculate the voltage drop (in volts) for your situation, OR ANY WIRING RUN, using the following formula...

Voltage Drop = 0.017 * Length * Current / Cable Area.

Notes:
1. 'Length' = total length of current run. ie if you have 4 metres from battery to unit, and you use a supply (+ve) cable and a return (-ve) cable, the total length is 8 metres. If you only use a supply cable (+ve) and use chassis for return, length can be 4 metres BUT the chassis return may not be as efficient (conductive) as a good cable due to poor joints. Generally better to use cable for critical items.

2. 'Current' is in Amps

3. 'Cable Area' is cross sectional area of COPPER CONDUCTORS measured in square millimetres (mm^2). It is not calculated on the nominal diameter (eg 6mm in your example above). If you do not know the actual sectional area, or cannot find it from cable drum or catalogue (Dick Smiths etc provide the data) then calculate it by counting the number of strands and accurately measuring the strand diameter (micrometer accuracy needed).
Area (mm^2) = 3.142 * diameter (mm) * diameter (mm) / 4

4. Where two different cable sizes are used (your case of 6mm and 5mm) then voltage drop can be calculated for each section of cable run.

Remember that when the engine is running, you will have more than 12V at the battery - charging voltage can be around 14.4V. This will mean that you may still have 12V at the fridge even if the voltage drop is larger than desired. I suggest that you check the fridge requirements with the supplier, as efficience can drop dramatically if voltage is too low.

cheers,
glids

As I am sure would have been mentioned before too,

Cable's aint cables!

(The important part for the purpose of this thread is the thickness/cross section of the copper wire. Often cable sold through places like Auto Stores etc looks nice and thick untill your compare the insulation too the copper "core". You may well find that the wire used by the auto lecky has more copper than most of the "off the shelf" 6mm you and I would get walking in to one of these places

Hi Tony C, who ever told you to use 6mm was steering you in the right direction.

Just about every auto electrician I deal with would have 5mm Automotive cable and as this is actually 2.9mm2, it’s way to thin for the distance to be able to keep up a minimum voltage drop while the fridge is running and as you are planning to run some lights as well, your fridge will probably work but it will be working hard and long to keep itself cool.

6mm Automotive ( 4.5mm2 ) is the thinnest size that should be used to power a fridge and in your case it would probably benefit your fridge and lights if you had run 8 B&S ( 7.9mm2 ).

The thinner cable means your fridge will have to work harder and longer so increasing the ware and tear unnecessarily.

Might pay you to see someone else.

Cheers

Why not check with Derek at Link ABR 4WD Accessories. Tell him what you want to do and he'll advise and supply if required. p.s. he's also an advertiser on this forum.