Just finished hooking up the Radio Shack Temp gauge/ voltmeter

To the second battery yesterday.  I was concerned that my Gel Cell was

Not getting a full charge or there was a mysterious power drain.

The battery is reading 12.1 v   [engine off]  and is getting a 13.5v charge
[engine on]

This seems normal and I am thinking to shift my trouble-shooting
elsewhere..?

TIA

Tom Myers
Rochester NY
90 westy