There aren’t a lot of choices for standard DC Connectors - people use the Cigarette Lighter or the Hella/DIN round connectors because that’s what’s on Fridges, Lights etc.
A very small and tough 12 volt 30 Amp connector suitable for all types of Fridges (including 3-way), Tire pumps, Radios (including VKS737 HF), Lights (up to 250 watts) and Chargers used by travellers, is now becoming widely available and reasonably priced. Anderson 30Amp Powerpole equivalents are available from -
www.altronics.com.au/index.asp?area=item&id=P7805 - Red $2.50
www.altronics.com.au/index.asp?area=item&id=P7806 - Black $2.50
www.jaycar.com.au/productView.asp?ID=PT4405. - Red+Black Pair $5.95
They are often available on eBay but make sure you get the 15, 30 or 45 Amp size (they all plug together)
An advantage of these connectors is that they are genderless, so you don’t need to buy both plugs and sockets and you can make up leads with a connector on each end they will always fit. It also allows a power supply to be connected directly to a battery to charge it.
The contacts are silver-plated so they are easy to solder, or you can crimp them if you have the correct tool. I use a small screwdriver to push at the back of the contact to
seat it into the shell. Contacts can be removed from the shell for repairs.
These connectors will not come apart or lose contact pressure from vibration. They are rated for 10,000 connect disconnect cycles. For continuous loads when used in pairs, the manufacturer recommends that current should be kept under 20 Amps. For short pulses less than ½ second they are rated at 55Amp. The link below suggests that 100 Amps won’t damage them ! The maximum wire diameter is 2.6mm (5mmsq) and with insulation maximum 4.4mm.
I will be standardising on these for all 12 Volt Connectors for 5 Amps to 30 Amps. Obviously Red is +12volt and Black is Earth, but the keys on these connectors allow the two to be connected in many ways, so I suggest everyone follows what is becoming an International standard. If looking at the open face of two connectors side-by-side with the HOLE on the UNDERSIDE, put the RED on the RIGHT. If mounting on a panel, it is best to mount with the holes down to prevent grit and moisture collecting on the contacts.
www.w5fc.org/pse_docs/KNOWLEDGE/anderson_powerpole_instructions.htm
www.nsw.wicen.org.au/main.php?page=tech/powerpole
Different types of Anderson Connectors are also available for higher currents, but they become VERY expensive. Some people use the Anderson SB (these are NOT Powerpoles) 50 Amp connector with the single-piece half-round
grey body - $18. These have the polarity marked on the body. Even though they are rated at 50 Amps, connector pins will only accept 8G cable. (Jaycar also sell a 120Amp Powerpole but these cost $38 for a Red+Black Pair).
For higher current applications (
Inverters, small
winches) up to 120 Amps I use the 9.5mm Spade Connectors as used for Fusible Links up to 120 Amps. Auto electricians sell Male and Female Nylon shells for these and Plug and Socket will cost about $6. I put the Red +12 lead near the rib/notch.
For small equipment, even the Anderson 30Amp Powerpoles are very big, so for small radios and lights that draw less than 5 Amps, I have standardised on the 2.1mm Coaxial plug with centre conductor as positive.
Plug $1.55 - www.jaycar.com.au/productView.asp?ID=PS0509
Panel Socket $2.65 - www.jaycar.com.au/productView.asp?ID=PS0522
Line Socket $2.45 - www.jaycar.com.au/productView.asp?ID=PS0526
For all connectors used outdoors with D.C., keep in mind that any moisture from rain or condensation will quickly cause corrosion and poor contact - I always apply Lanolin Oil (Lanotech, Lanoguard etc ) to the connectors (Vaseline is an alternative, WD40 soon evaporates.)
Here is a photo of my power board that has most of these connectors on it (I like to be prepared) to show how they compare in size.!
http://i23.photobucket.com/albums/b356/MikeAus/Auto/PICT2566DCConnectors100k.jpg