Question about battery substitution

[BobAsh]

I did a search on the subject, and came up with differing views, so I'll ask it directly.

Can you directly substitute a single 18650 for the 3AAA's in the Husky 3W Cree LED "145 lumen" flashlight.

I've seen that some guys are doing it and others are using driver boards, but I don't need multiple outputs. I just don't want to do something ignorant.

Thanks in advance.

 

[LED_astray]

I don't know that light, but in general I'd worry about replacing 3AAA with anything because that type of design is notorious for relying on the AAA characteristics to function reliably.

Let me try to explain. A typical simple LED circuit uses a resistor to limit the current the LED sees when powered by the battery. It is possible to rely on the AAA battery resistance and save the few pennies on a separate resistor. Too often manufacturers do that. If they have, using different batteries is equivalent to changing to a much lower value resistor, which increases the current, and that risks blowing the LED.

If you're up to it, you could carefully measure operating voltage and current with 3AAA and, briefly, with 18650 and compare. It may work. If not, it is probably possible to pick a resistor value that would limit the current, make the light reliable, and work with acceptable brightness.

 

[BobAsh]

Thanks. Sound advise for going forward if I can't find someone with specific experience with this light.