Great info, especially about the reverse polarity possibility. That explains why so many of these lights specify reverse polarity protection circuitry. I thought it might be because people were inserting the batteries backward.
Just to be clear, no offense or argument intended by my previous post. You are clearly knowledgeable and I was just asking as a check on my own thinking. Your points are all good. Based on the O-Light stats above, my thought is that, if I have two batteries, getting 15 hours at 85 lumens is better than 9 hours at 120, even if I have to change batteries midway. I live in an area where we experience power failures a couple of times a year, and this would be the most common emergency scenario for me.
For the car, as the OP asked, carrying spare batteries is good planning of course, and this way only one spare at a time is needed. If my light requires two batteries, I have to carry spares in multiples of two. You're right that the cost is not the major issue, but carrying say, four batteries rather than eight seems significant. Perhaps I've been incredibly fortunate, but I've never experienced an emergency where I would have needed the high mode for more than few minutes. Why would one need 4-500 lumens for an hour or more?
I am familiar with Selfbuilt's stuff; you are right, it's really good!
