Batteries

A week or so ago, I got a check engine light on our truck.  The auto parts store's reader recorded a code, but when they plugged it into their computer, the code was not in their system.  I reset the code by disconnecting both batteries (a Cummins diesel has two 12 volt batteries) and everything was OK until this morning, when the truck batteries didn't have enough umph to start the truck.
I managed to charge them enough to start and took it to NTB where I purchased the batteries in 2013.
The good news is that now everything is back to normal.  The bad news is that two batteries that cost me $200 five years ago cost $396 to replace today.