12V is more modern, the alternators produce more current for brighter more powerful headlamps/taillamps or other 12V accessory. 12V stuff is also rather common, and the batteries tend to be available in newer types with longer life. The power of an electrical item is measured in watts. Watts are Volts X Amps. To get say 100 Watts, on a 12 V system i s 8.3 Amps. To get the same 100 watts on a 6V system is 16.7 Amps. Amps is a unit of current or you could call it flow. Picture a hose, one the size of a garden hose, and the other the size of a straw. You can drain water through the garden hose easier than the drinking straw. Same goes for electricity. To get 100 watts on a 6V system you need to have more flow. Hence larger wires. 6V systems are therefore slaves to restrictive wires, corrosion etc. destroy the flow and then the number of watts you can use drops off.
Now you can definately deal in 6V, I like it well. But you have to make sure your wires are good and corrosion free, and that all connections are clean and tight, and it helps to put some anti-corrosion grease over them to prevent oxidation and loss of current.
Many people will choose to convert to 12 volt when:
Having electrical problems,
Having a dead or dying generator,
Having a dead 6V battery and perhaps other issues as well.
The idea being that your costs are some what covered anyhow by saving money over the 6V components.
Why not to go 12V? Originality, 6V has worked fine on many tractors for a huge number of years, and can be made to work with no teething issues regarding burnt points or what resistor to add to the coil, or if your starter will do alright with 12V's etc. You can solve many 6V problems by cleaning the grounds, getting them nice and tight, and applying some anticorrosion grease over them to keep oxygen out. As well as fitting larger wire/battery cables as you see fit.
Last edited by P B G on Sat Jan 30, 2010 12:42 pm, edited 1 time in total.