6 volts or 12 volts? Alton or dynamo? Well, everyone is free to do as they wish with their bikes, but for all practical purposes 12volt is by far the most practical solution if you want long term reliability and decent lighting. However lets look at some of the various options available. The easiest and simplest thing to do is to fit an electronic regulator. However to get maximum benefit a belt drive conversion is required. This will speed up the standard Lucas E3L and give you the same charging characteristics as the original 6 v set up. Like many people I opted for the excellent DVR2, and with good reason. The DVR2 eliminates the problem of the battery discharging on tick over, I had previously tried another electronic regulator and at idle there was always a discharge indicated on the ammeter. Retaining the original 6v dynamo has some advantages over having it rewound for 12v operation. Rewinding an E3L to operate at 12v will give the same charging characteristics in 12v operation as an E3L operating at 6v, but because the windings will have to be wound with a thinner gauge wire (to get it all in) there will be an increase in resistance and more heat will be generated, and there will be no net increase in output (60 watts). An E3L with its original windings regulated by an electronic regulator will give an increased output of about 80 watts. The Alton alternator has a much higher output (150 watts) maximum, and a claimed 90 watts at cruising speed, however around town in traffic it is no more efficient that an E3L, (unless the latest model has been much improved) and of course an Alton conversion will cost a lot more than the price of an electronic regulator and belt drive kit (£350+VAT) and then there is the additional cost of a regulator to be added. I personally used to run an H4 halogen headlamp with my 12v electrical system, and I fitted an LED pilot lamp, LED speedo and rev counter lamps, and an LED stop tail lamp. I had no problems with this set up. The E3L was able to cope perfectly well with the demand, but when an LED dipping headlamp became available I did away with the H4 in order to give the E3L an easier life.
John