by John R » Sun Feb 22, 2015 1:42 pm
A few thoughts on 6volts versus 12volts. There's no fundamental advantage in 12v apart maybe maybe parts availability of bulbs and this has to be balanced against finding and fitting new non-standard coil and regulator, maybe horn.
A 60 watt generator has the same power whether 6v or 12v, the former producing 10amps max current, the latter 5amps (by Ohm's Law, watts = volts x amps). Unless you fit a higher wattage 12v generator you have gained nothing power-wise.
Either generator unregulated will output at up to about 50v. A 6 volt generator is optimised for 6v but can sometimes be used with a 12v regulator to output at 12v. However this isn't good as you'll find the low speed output is way down.
Your 52k could be rebuilt optimised for 12v with special new field coils and re-wound armature. A good specialist can do this for you, but there aren't too many about. BUT, even if designed for higher output than 60w this then may overheat. The existing physical armature, body etc has a maximum heat dissipation rate. Outputting more power generates more heat and that could lead to failure.
There are 12v generators with higher output (VW?) that can be made to fit but for my money stick to 6v. Stock, easy. Although original sealed beam was just 30w you can use a 45w and still be within its capabilities, just, unless you haul round at under 35mph.
A 6v 45w headlamp is in principle no less bright than 12v 45w. However, there's the proviso that watts is the power used and is not a measurement of light output. In practice with conventional sealed beam lights they will be the same. Going back to when bikes vibrated and shook more than now, bulbs had lower light output for the wattage to enable tougher filaments. Bikes stayed with 6v longer because 6v filaments are tougher than 12v of the same wattage.
A couple of practical points - you can get double sealed replacement bearings that will serve better, and motoring a generator will indicate that it's not totally shot but won't say whether it's 100%. You can try running the bike at night and see whether it's delivering ok. The only proper test is to have the armature out and have it fully tested on a growler and to check the resistance of the field coils. An older style auto-electrics place can help.