Everyone knows you must carry extra batteries. I am using rechargeable batteries most of the time today. I have a few types of rechargeable batteries, but highly recommend eneloop batteries. These are great and I highly recommend them. Here is a good blog on the eneloop.
We all know the battery will run out of juice sooner or later. That’s why we carry extra batteries.
Battery Tester Saves
Years ago I was using rechargeable batteries, but found them a pain. The earlier ones I used in the 1980's just didn't hold a charge and while I had them in the bag charged, they would loose so much power I found them dead when I got ready to use them.
For many years I was using the alkaline batteries and then came along the lithium batteries. These were great. They weighed so much less and lasted 8X longer than the alkaline batteries.
If you’ve used them you know they’re expensive, which inspired me to test them. I wanted to see if they all needed replacing. I would test the questionable batteries with a battery tester and found most of them were still good.
When I pull the batteries out and test each one, I usually find that only one is dead. I often only replace the one battery, rather than four.
Be sure in your camera bag you carry a battery tester--it is a great investment.