I *always* replace the batteries on sys3 boards. The are well past the age when they start to leak. If you catch it early, it isn't usually as messy as alkaline, but it can still do just as much damage if left unchecked. I've had a few that were fine, and a few that were leaking.

You don't need a remote battery holder. Remove the old coin cell, and solder in a CR2032 holder and a CR2032 battery works just fine.

However, this year, there was finally a working version of NVRAM released for sys3, so that's now an option too.

I agree--storage conditions certainly play a big part. But batteries are still batteries, even if stored under perfect conditions.

The lifespan is typically 7-12 years for coin cell batteries, although it's usually just stated as 10 years. Depending on the current draw, they could go dead before then, but that doesn't necessarily also mean they will leak after they are drained, or would leak immediately after the 10 year mark.

System 3 games were made between 1989 and 1996. That's 22-29 years, depending on the age of the game, plus whatever amount of time the batteries were sitting on a shelf. That's well past their typical lifespan.

I've replaced many coin cell batteries on system 3 MPUs in the past few years and have had to clean up after the mess they made (not nearly as bad as alkaline, but still requires some clean-up and the affected components to be replaced). Like I said, batteries are batteries, and it's better to replace them as a matter of preventative maintenance rather than wait for a problem to develop, especially if they are 20+ years old.

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