Building 1-1,4V battery life indicator advice - under 5$

[DuncanSteel]

Hello

I would like to build a battery life indicator that could be hooked up to Philips oneblade, what are my  realistic options? Some quick advice would be appreciated.

Goal:
Voltage range: 1v to 1,4V
Device size preferably: 0,5 x 15 x 30mm

Points of interests:
1. Did not find any already existing solutions a person could buy for this voltage range.
2. Could you recommend some components to look into?
3. Maybe use cheap arduino clone, boost converter, some LED-s & a push button?

[Nusa]

Sounds like a job an AA battery tester would work for. They comes in many different shapes and sizes. The cheap ones are under a buck on ebay and other such sites.

[DuncanSteel]

I have been thinking & came to conclusion that all I need is a switch that will turn off the led when voltage reaches 1V.

Say the led that requires 2V must light on if voltage is over 1V & not light up if voltage is 1V or below.

Use Case:
1. User holds the switch & voltage is over 1V (led is on)
2. User holds the switch & voltage is below 1V (led is off)

Is there any simple way to achieve this?