Originally Posted by Frankenbiker
This circuit allows you to vary the light output of your single or dual 20 Watt headlamps. It will allow you to use less power if you only need a headlight "to be seen" by and then ramp up the light output to various levels (e.g., 7, 10, 20, 30, 40 Watts) depending on how much light you want or need by pressing a momentary switch that will cycle you through the settings. This saves battery power, to a degree, so you're not blasting away with 40Watts when you only need 7 Watts.
I don't know if the twin has all the features of the twin plus but other features are:
- fails over to second light if primary light fails (and you're not using both anyway)
- runs over volted at 13.2v (unless you change the default) until the battery voltage drops lower
- has warning flashes when battery gets low
- goes into emergency low power settings when battery is too low
- has SOS flashing mode
- slow starts bulbs to maximize bulb life - also helps Li-ion batteries because their cut-off circuit could trigger if connected directly to high wattage bulb(s)
- allows you to use higher voltage battery setups without damage to bulbs - e.g. I have a dual 7.2v RC NiMh setup that puts out close to 16v when charged