Thanks for the helpWatt is a unit of power and not current. Watts = Amps (current) X Voltage. So 3W at 6V would be 0.5A of current. If you have a multimeter, you can measure the current while the light is on. Select the current function on the multimeter and choose DC. Put the probes in series with the circuit.
I didn't know that. Thank you
This is a drop bar bike & it's a hassle to attach a switch.It would be convenient to have the display turn on the light.Just based totally on a guess, they say "500" on the side and from the very blurry photo of the front I'm guessing those are Cree XM-L or XM-L2 LEDs so if that 500 is lumens which is a reasonable level for these LEDs considering it's a alkaline powered light that would mean about 4-5w not including driver losses. But those are just guesses and you can drive those LEDs much harder, like 15-20W if you are doing some serious hot rodding, but those lights are not and you can't get that much from alkaline batteries and that 500 may be optimistic. Honestly I would just get a separate bike light that can put out some actual light, lighting is safety equipment and the last thing you want is to be going potentially quite fast and not being able to see very well.
You can use a solid state relay to turn on a light that runs on your full battery voltage. The spec for the control signal on those is usually 3 to 30V, so 6V is just right. Switching an SSR draws low current on the control wire, and will not overtax your circuit.This is a drop bar bike & it's a hassle to attach a switch.It would be convenient to have the display turn on the light.
I ordered a light for another bike & will be installing it this way.I have the flashlight's sitting on a shelf and it was worth a shot to see if it would work.You can use a solid state relay to turn on a light that runs on your full battery voltage. The spec for the control signal on those is usually 3 to 30V, so 6V is just right. Switching an SSR draws low current on the control wire, and will not overtax your circuit.