The Battery Tender is actually a "maintainer".
As such, it is designed to be used for extended periods of time.
It is not a constantly charging low amp "charger".
The advantage of the Battery Tender was the computer control that determines when the device actually "charges" at a very minimal rate of amperage.
This avoids "cooking" a battery that is fully charged.
I have had my ZR-1 on a Tender since 1997, except when it is driven or during moves.
I burned down no houses.
No battery ever boiled.
No damage of any kind to the wiring or any electronics.
I have installed the permanent connectors on all of my cars, enabling me to avoid the hassle of the alligator clips.
I add gold battery bolts with a slight extension from original.
Don't go too long as you do not want to force the lugs out of the battery, just long enough to accomodate the ring terminals more easily. The ring terminals attach to the threaded extension on the front of the bolts. This makes for not only a reliable connection, but one that looks professional.
There are newer versions such as C-tek, but I have had most of my Deltran Battery Tenders for over 20 years.
I even have two that have the Corvette Museum Face, from back when they were sold by them.
I could not be happier with them.
I simply "unplug" the connector, and away I go.
I recognize alternate thoughts and methods, but this has worked very well for me a VERY Long time, I think since the very early 90's.
Marty