accidentally put batteries in backwards on parallel box

[Jack Wilson]

i was being kind of careless and accidentally put the battery in backwards and there was a tiny spark and there is a very small black mark on the negative of the battery that was upside down i put them in a regulated mod and they still work but is there danger in using it in my regulated mod?

 

[sonicbomb]

It might be, or it might not. batteries are very cheap to replace.

 

[gin828]

Replace your batteries....Both of them

 

[SteveS45]

Visual damage might be minor but it is what you can't see that could be a concern. As @sonicbomb stated batteries are cheap enough to replace to protect against the unknown.

 

[Verb]

A $10 mistake. Replace them and move on. Recycle the old cells.