Swapping sim cards between 2 NightHawk MR1100

I have a working Nighthawk MR1100 hotspot and a second one for back. The current router let the battery die, I put in another battery and it has worked about two month. I lost wifi and noticed a message saying battery not charging due to heat. Battery had 70% charge. I put a fan on and restarted and it working now. If I have problems can I swap the sim card to the backup MR1100? Thanks