I have a '97 first run Boxster
Car is stored in underground garage for days, weeks and months all year and will be driven between those times.
What recommendations and thoughts for battery Conditioners and Minders for infrequent use, can leave it on and drive with it, works without plugging into AC outlets and is great in an unheated underground garage with Canadian winters as well as any thoughts on Battery Brain?

 

You will need something that plugs into an AC outlet if you want to keep the battery charged, unless you want to disconnect the battery every time you park the car. You can get a battery tender with a quick disconnect cord, so you don't have to mess with a connection at the battery, let alone even have to open the hood. Just disconnect and drive away.

If you disconnect the battery (or have the battery brain do it), it will make getting into your hood very difficult. The keyless entry will lock you out, and you will have to pull the emergency cable in the wheel well to open the hood.

I dont think there is enough room in the compartment for a battery brain.