When using a Battery Tender during the "in activity months" can you leave the battery connected to the car? Or do you have to disconnect the battery cables from the car? 

You can leave it hooked up.

Why thank you Sir...now I feel more comfortable about its use. 

I use a "Battery Tender" brand battery tender which has the permanent hook up cables that you simply plug into. I love it and have bought them for my Vette and all 3 of my motorcycles....Leave em hooked up and forget about them, they do all the work for you...

I have a Schumacker charger.....same as a battery tender.... I have it mounted on a bracket behind the battery, and hooked to the battery terminals permanently. When ever I want to hook up I just open the hood and plug an extension cord in. Close the hood and were good.

I use a "Battery Tender" too. I found a rubber mounted bulkhead female at one of the car shows that matches the connector on the end of the cord. I mounted it behind the bumper so I plug it in every time she's parked. I wish it had a voltmeter even though there is an LED to provide some indication. I found a Black and Decker voltmeter (was less than $5 at a factory outlet) that works in a lighter socket that I'm going to mount to the side of the battery tender.

Brian is right, & your clock won't have to be reset in the spring either. Spent a lot of time up your way in the 80's & 90's. Tug hill & Old forge sledding EVERY WINTER, what a BLAST !! Put up the Vette, & WARM UP THE SLED. Have fun

kendo2...I snowmobiled in Old Forge/ Eagle Bay/ High Market/ Tug Hill from 1974 till 2009. I stopped in 2009 when my favorite Skidoo MXZ sold for $11,000.00. Thats more than I paid for my vette. $11,000.00 bucks for a seasonal recreational vehicle that sits on the lawn for most of the year...well can' justify that. Still love the sport and plan on getting a rental to ride the trails of Old Forge (best snowmobile trails in the eastern USA). I do miss having my own but rentals are available. One of the greatest winter sports going!