Can I use both?

[Woodsman4god]

Hi guys

If I have a flashlight that takes aa batteries and I got a replacement bulb that is rated 2.7 - 9.0 volts can I use both alkaline AA's and the 14500 Lithium ions?

 

[Lou Minescence]

Sure can. If you have an emitter that draws a lot current you may find the minimum voltage point is triggered on alkalines and the light will act strange. Try alkalines and see if they can supply current fast enough for the emitter. 14500's should work perfect.

 

[LEDninja]

2 AA alkaline starts at 3V dropping to 2V.
2 AA NiMH starts at 2.7V dropping to 2.4V.
You are stuck using 14500.

If you are using regular batteries, you need at least a 3 cell flashlight.
3 AA alkaline starts at 4.5V dropping to 2.7V.
3 AA NiMH starts at 4.05V dropping to 2.4V.

This looks like a buck only circuit. They need 4V to work properly. It runs dim between 4V and 2.7V.
4 AA alkaline starts at 6V dropping to 4V.
4 AA NiMH starts at 5.4V dropping to 4.8V.

For example:
The Terralux TLE-6EXB is for 2-3 cell flashlights (boost circuit).
TheTerralux TLE-6EX is for 4-6 cell flashlights (buck circuit). You got the equivalent of this one. Buy a 4 cell torch that takes the same type bulb you have.

 

[Woodsman4god]

In the end I was planning on using the 14500's but was hoping it still might work with alkalines or nimh for storage etc just to have a light even if it just worked in low mode by the night stand