I have a 1985 Camaro that was my summer car, now on collector car insurance, just driven to car shows and club events in the summer. It has a grandfathered Canadian Tire Eliminator battery from when they had a lifetime warranty that's been replaced a couple of times when it failed to start the car in the spring. The last time CT tried to not honour the warranty, claiming they changed suppliers, but eventually agreed. Not wanting to go through that hassle again, I got a Deltran Battery Tender Plus that I use every winter and never had a problem with the battery again. I also bought a Battery Tender Jr. on sale at Canadian Tire for my riding mower.
The Deltran Battery Tender was the first device of its kind on the market many years ago. The difference between these and cheap trickle chargers is that they keep the battery in a floating fully charged state without boiling it dry like a trickle charger can. Now there are other brands of battery maintainers available, some cheaper than Deltran, but you'll have to do your own research to see what's best for you. The BT Plus is kind of pricey now, $94 at CT, but the BT Jr. is $50 regular price at CT. It has lower maximum amps, but if you have a regular battery charger anyway, that doesn't matter.