There are two easy solutions
When fixing the battery in your Dreamcast, there are two methods to consider.
Method 1: Install a new rechargable Lithium battery
Method 2: Remove the charging capabilities, and install a non-recharagble Lithium battery
Method 1 is actually slightly easier to do, but if you’re like me and tend to play your consoles in short bursts ( < 1hour ), then you may find that even with a fresh rechargable installed you still get asked for date and time, due to the battery not having enough charge.
Note: If you decide to go this route, you must use an ML2020 or ML2032 which need around 3.2v to charge. If you use an LIR2032, it requires 4.2v to charge, and will not charge correctly.
Method 2 is a little more complicated, because you have to prevent the console from attempting to charge the non-rechargable battery, but it’s also very convinent (and cheap) to replace CR2032 batteries as they run out of juice. With this method, playtime doesn’t matter, and if you’re into old consoles, you’ve probably already got some CR2032 batteries lying around. If not, they are very cheap, usually about $0.40 each.
In this guide, I will show you how to perform Method 2, and with that knowledge you will be set up to do whichever method you desire.