system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:Why do (AA & AAA) batteries in a package seem to very rarely leak even after sitting in the cupboard for years and batteries left in a dormant device leak after a much shorter time?

Why do (AA & AAA) batteries in a package seem to very rarely leak even after sitting in the cupboard for years and batteries left in a dormant device leak after a much shorter time?

(....And then ruin the controller unit on my gas fireplace)
gpt
The corrosion is caused by hydrogen gas escaping the battery, allowing the battery to leak, this still happens when on the shelf, but at a slower rate. When your device is 'off' there's a small amount of drain happening causing extra gas to be produced, also depending on what the contacts are made of on the device they made corrode as well (causing it to look like more battery corrosion).