I would argue that disconnecting the battery for long periods of time, is the wrong thing to do. I doubt when you disconnect your battery, that it will be fully charged, and when disconnected, it will continue to gradually lose charge.
The way to get the longest life out of lead-acid batteries, is to keep them fully charged, or as fully charged as possible.
Your driving pattern is like mine, as my Puma is a second car, so it is used very infrequently, and I keep it connected to a battery charger, via a permanently attached connector.
There are plenty of charger manufacturers in the market, but I have used CTEK for many years(In fact, I have 3 different models!):
The one I would recommend is the CTEK MXS 5.0:
https://www.ctek.com/products/vehicle/mxs-5-0
This model has automatic charging and a float/pulse system, which is the most efficient maintenance mode when a battery is connected for long periods. In addition, it also has a recondition mode, an automatic desulfation program and can also charge the more modern AGM batteries, which you will probably have on your next car.
Under my bonnet, I have the battery terminals permanently connected with a CTEK Eyelets and Indicator Panel (2 sizes of eyelets are available) to check battery status. I also use these on our other 2 cars, which are driven more regularly, and are there to check the battery condition, at the same time as oil and screen-wash bottle. With the Puma, I just leave the charger connected for ‘connect and forget’, and just disconnect when I go for a drive. In this way, the battery is kept charged with the float/pulse system. This allows for the alarm to be working, as well as the central locking.
https://www.ctek.com/products/vehicle/indicator-eyelet-m6
With the lock-down, I am also ensuring the other 2 cars are kept fully charged!
