2 Laser pointers powered by a single 6v lantern battery

[xgabrielx]

Hi, I need to wire 2 laser pointers to run simultaneously of a single 6v lantern battery. The pointers originally each took three button cell batteries (1.5v) I've measured the current being used by each pointer at 20 milliamps. Is it simply a matter of using two resistors as a voltage divider to get 4.5 volts then wiring the pointers in parallel across that? What resistor values do I need to use for the voltage divider to maximize battery life? (Not hugely important) If it helps, I measured the resistance of the pointers at 1.3K each, though I understand that may change under operating conditions.
What I really need to know is, what is the best way to do this, wasting as little energy from the lantern battery as possible, and preserving the lifespan of the pointers as much as possible. Ideally they would be operating a little below their normal output.

 

[Diver300]

You would be better to use a low-drop regulator to give 4.5 V from the 6 V battery. It will be much more efficient than a voltage divider.

You could just put a 75 ohm resistor in series with each pointer. That would give you about 4.5 V with a 20 mA load.

 

[Sceadwian]

The single resistor is probably the easiest solution.

 

[xgabrielx]

Thanks. I'll do that instead.

 

[MikeMl]

Thanks. I'll do that instead.

Let us know how you make out