I have a Canon EOS 5D Mark IV, along with 2 original Canon batteries, 2 aftermarket batteries, and 2 chargers (the original one and an aftermarket one that charges 2 batteries at the same time).
For whatever reason, every time I take a battery out of my Canon, the "replacement" one that I pop up always seem to never really work properly.
For example, I can shoot footage for about 80-90 minutes. As soon as the battery dies, I pop in the next one. The camera shows it full, but then the battery dies in about 2-3 minutes. I thought it was perhaps due to an aftermarket battery or charger, but this seems to be the case even with the original Canon battery and the original charger. It doesn't matter what battery goes first, the second battery that goes in seem to have the issue.
All of this equipment was purchased about 5 years ago.
Any help would be greatly appreciated.