I live in NC for four months in the summer to escape the FL heat. I leave the Prius in FL but press the disconnect button to shut off as much battery drain as possible. Is there more I should do to prevent the battery from draining?
Golly, why not drive it up there? Anyway, if you leave it for four months, the 12V battery should either have a battery tender clipped to it (assuming you have a secure storage place), or disconnect one of the 12V battery leads (this will erase any options you have set in the audio, etc.).
If you park it outside (not in a garage or carport) I would suggest a solar powered battery tender. Otherwise a 12V trickle charger is the best option. After all............Florida the sunshine State!
Never leave a trickle charger constantly connected to a 12 vdc battery, as you will destroy the battery. Use a "smart" battery tender that will automatically keep a "float" charge on the batter. I use the VDC Electronics BatteryMinder, although I'm sure you can find other brands that work just as well  12 Volt-1 Amp Charger and Maintainer A battery tender cannot be used to recharge a dead battery, for that you will need a normal battery charger. However, the battery tender is safe to leave connected 24x7 If you have to leave the Prius outside, a solar charger may work. Or, just disconnect the 12 vdc battery at the underhood jump/service point. You will lose all radio presets, and you will not be able to release the rear hatch unless you crawl into the rear and manually release the lever. After the battery is hooked up again, you will have to "normalize" the anti-pinch feature of the power windows
I left my Prius for 5 months earlier this year (I didn't realise it was going to be that long) and I pressed the button to disable the SKS. I returned to a flattened battery. I was able to start the car with a jump and it's been fine since. Next time I shall disconnect the battery if I leave the car for any significant time.
Since you will be gone for four months, I suggest that you just disconnect the 12V battery and call it a day. I personally would not be comfortable having a battery tender plugged in and unattended for that period of time. A relatively easy way to disconnect the battery is to open the hood, then find and open the main relay/fuse box near the inverter. Open up the red door covering the dedicated jump terminal. Remove the nut that is revealed, then remove the lug and wire below the nut. Put the nut back on the threaded stud. Close the red door and put the wire connector on top of the door. Close the relay/fuse box and the hood. Now the car should be totally powered down. Lock the doors manually (hopefully the windows were closed before you started this process), and the car is ready to be left alone during your four month absence. When you return, use the mechanical key inside the fob to open the driver's door, then you can reverse the process described above.
Patrick At my hobby farm, I've left batteries hooked up for 7-8 months on the Battery Minder with no issues whatsoever. That is on the garden tractor, which I only briefly use during the summer months The best way to kill a battery is to let it chronically discharge over time. What I like about the Battery Minder is that once it reaches a float charge level, it automatically desulfates the battery. The second best way to kill a battery is to hook up an unregulated or "dumb" battery charger, like a trickle charger, and leave it on 24x7. You'll cook the battery jay
