Eli5: Why do small batteries sometimes need their seemingly clean contacts wiped clean in order to work in a device?

Question

Eli5: Why do small batteries sometimes need their seemingly clean contacts wiped clean in order to work in a device?

In: 19

Answer 1

The small batteries might not have the spring contacts forceful and sharp enough. Bigger batteries you might insert with a snap and rotate them a bit, which would scrape the contact points clean. I’ve noticed that coin cells in calculators and similar are usually not held with much force.