Sweat Spot On Battery ?

[Biker1]

Originally Posted by jonnythan

You will notice that dead center over that spot, on the underside of the cover, is a little hole.

I just took a look and it appears that the tiny hole is approximately 1/2" under the "sweat spot" but may be a contributor to the spot.

UPDATE:
I think I solved the mystery.
The "spot" is caused by friction and/or pressure between the high area of the inside of the cover and the battery, or more specifically, the coating on the battery which appears to have a rubber consistency.
The friction and/or pressure is letting the oil? leech out of the rubbery material.
I have 3 OEM batteries that I have checked with the same spot on them even though they are removed from my Diamond.
And there you have it, at least I think that is the cause