Vortex Sparc CR2032 Conversion Battery Hack
Ok the one singular hemorrhoid-ial pain in the butt about the Vortex Sparc red dot is the goofy CR2354 that no one has... literally it is a freaking special order battery which is usually out of stock from my experience. If that battery was some other voltage other than 3V the Sparc power source should be strongly reconsidered.
The Vortex does not blink or dim when the battery is low, but instead is does something extremely weird... it will not turn off. Instead of cycling off after holding the power button for 4 secs it turns off until you let go of the button and then turns on again. Definitely weird as a low power indicator which initially made me think something was wrong with the sight and I even removed it and packed it up to send back to Vortex. After realizing that the unobtainium-like CR2354 was unobtainable, I reached for an industry standard 3V CR2032 available anywhere. The CR2354 is basically the larger diameter, thicker, and longer running version of the CR2032 so just expect the CR2032 to not deliver the same run time.
The problem with just plopping in a CR2032 is that the spring on the battery compartment in stock configuration is not long enough to make connection to the thinner 2032. The very simple solution is to just pop out the battery cover spring and stretch it out by about 30% and then reinstall. If you are careful you may be able to stretch it out in place. Another solution is to just add a dime or nickel on top of the CR2032 battery. That's it and now you have a low cost Vortex Sparc red dot that is a deal among high quality red dots that will now run on standard CR2032 batteries and can still use the longer running CR2354 when you can find them. If you are out in the backwater of some foreign country on tour, you will be able to find 2032 which will keep you going.
Vortex Optics - http://www.vortexoptics.com