Parking the Prius for 4 months

Just one - the negative lead to the body is easy to remove/replace. Make sure to put an insulated cover on the lead to avoid touching any metal while disconnected. You will need to reset your radio presets and the auto-up for the electric windows when you get back. I would also make sure that both batteries are at a high State-Of-Charge (SOC) before storing your Prius.

JeffD

 

Make sure the HV battery has a high level of charge before storing the car (5 blue or 6 green bars on the MFD).

The main supply cable from the 12 volt battery positive terminal plugs in to the terminal connector so no need to remove the terminal lugs. Only this one connection need be removed.
It would be best if the 12 volt battery could be left on charge from a battery minder or a solar charger. The solar charger can be connected direct to the battery, "do not use the cigar lighter socket" and will work well if the car is left outside. Alternatively the battery and solar charger can be taken indoors and the solar charger put by a window.

John (Britprius)

 

Yes, you could remove either. Correct practice is to disconnect the negative terminal first if you are using metal tools.

The reason for that is if you short the positive terminal to body ground with a metal tool while the negative terminal is still connected, this will result in a large spark and possible harm to you or the car.

If you disconnect a 12V battery cable, remember that the electric hatch opening switch no longer will operate, so you need to close the hatch in such a way that the lock does not engage. Or, plan to crawl through the passenger compartment into the hatch area to find the mechanical hatch lock release which can be accessed after the folding hatch floor is removed, with access via an opening in the black plastic tray over the spare tire. The opening is at the rear of the tray, in proximity to the latch mechanism.

An alternate approach is to disconnect the positive lead which bolts to the dedicated jumpstart terminal within the main relay/fuse box next to the inverter. This works well because it is much easier to open the hood from inside the passenger compartment. You can lock/unlock the driver's door using the mechanical key within the fob.

I suggest that you fully-charge the 12V battery prior to storage, so that you won't have to worry about the battery being able to power up the car when you return from your trip.

With regards to storage, I suggest that you change the engine oil/oil filter immediately prior to storage, and inflate the tires to 44 psi. Ideally, raise the car on jackstands to prevent tire flatspotting.

 

Steve that will work perfectly well maintaining a good level of charge on the 12 volt battery.

John (Britprius)