Hi all,
Currently using 2 EGO-T battery, with no problem. Charging and usage is normal, no problem whatsoever.
But one of the battery contact point have some rusty brownish residue (left side on the picture). Trying to clean it but it wont come off.

May i know what is the residue and will there be any problem in the future? What caused it really?
Currently using 2 EGO-T battery, with no problem. Charging and usage is normal, no problem whatsoever.
But one of the battery contact point have some rusty brownish residue (left side on the picture). Trying to clean it but it wont come off.

May i know what is the residue and will there be any problem in the future? What caused it really?