Apollo 13 taught us the importance of standardization. Engineers learned to fit a square peg into a round hole. Terrific. I initially started hiking/backpacking/camping with the intention of using nothing electrical. Instead of using a flashlight, I'd use a glow stick... When you're done laughing, and you should be laughing, don't worry, I've changed. I bragposted my Prometheus Alpha. I love this flashlight. I look forward to using it, and look for excuses to use it. It was stupid expensive, and I don't care. I'm also an Amateur radio operator that uses many handheld radios. Because why have just one hobby that can be expensive, when you can have two for twice the price? So I also have a TH-D74, an FT-2D, and an Anytone AT868UV (cuz digital modes). I have a GPS. And all the batteries are different. I could get packs for the HT's that allow me to use AA batteries like the GPS uses, but then I'm transmitting at low power. I'm leaning towards another solution for standardization. I've become a fan of the 18650 battery (example: https://www.18650batterystore.com/). I have nothing to do with the website, it was the first link in google when I googled 18650. This battery is a 3.6 to 3.7 volt and has from 2500 to 3600 mAh. What is great about it, is that you can charge 4 simultaneously on a USB port. Two cells hooked in series will have a voltage of 7.2 to 7.4 volts. Plenty of voltage for a handheld radio. The two cells would also provide enough power for 24 hours at a 5-5-90 duty cycle. One cell could be used in the flashlight, and one could be used in a GPS. The bonus is that two CR123 sized cells could replace a single 18650 cell. Alkaline CR123's are common enough you can find them for sale at supermarkets. The points I'm making are: 1) AA batteries aren't useful for high power deep discharge electronics like what you would use in a field/extended field situation. 2) Having to depend on lots of different types of batteries requires that you carry lots of different types of batteries... and they can't be switched out. 3) I spend entirely too much money on stuff... And last... I'm going to design battery cases for my handhelds so that my flashlight and handheld radios can all use the same batteries, charging station, and alkaline CR123's if it comes to that.