[Victor]

The dealer PDI information stated the 12V battery should be charged if the car is left unused every 2 weeks. Trickel charge is recommended. If left longer, the engine should be run in maintenance mode for 30 minutes every 2 months. If the HV battery goes flat, it has to be changed

Best would be to get someone to give it a short drive once a week. For parking at the airport for 2 weeks or more, maybe you should put a portable gas generator with 12VDc output (or mains and a charger) in the back incase the 12V has gone flat so you can get enough charge to start up.

 

[Victor]

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I wonder how likely it is that the 12v battery would run down if left for two weeks. Usually when you arrive at the airport after a long drive the battery will be as fully charged as it is ever likely to be. I have never had a problem with other cars, including ones with an intruder system switched on while I was away. Is there really a larger load than normal when everything appears to be switched off (except the alarm)?

The 12v battery in the prius is a lot smaller than on a normal car as it doesnt need to turn a starter motor. Therefore the peak load it a lot less so a smaller unit is ok, but this leads to a smaller overall capacity. Think of it as a motorbike battery! You can replace the standard one with a higher capacity unit, but I dont know what is involved off hand. Space maybe the main problem.