Storing a hybrid vehicle

What I have done with my old D-Max was to use a smart charger but connect to through a time switch set to turn it on for 15 minutes per day which is enough to keep the battery fully charged.

I found this:

""Do I have to take special steps to protect the battery of my hybrid vehicle if I plan to store the vehicle for an extended period?

In addition to the "storage tips" for our conventionally-powered vehicles, our hybrids require additional steps for each battery, as the hybrid vehicle battery and auxiliary battery will discharge and their condition is liable to decline.

To prevent excessive auxiliary battery drainage, charge the battery at least once every two weeks by powering on the hybrid system for 20 minutes with all non-essential electrical accessories (such as air conditioning and audio equipment) turned off. It is not necessary to drive the vehicle, but do not start the hybrid system in an enclosed area unless the tail pipe is connected to an exhaust hose to prevent harmful buildup of fumes. As an alternative, you may disconnect the negative terminal of the auxiliary battery.

For the hybrid vehicle battery, charge the battery at least once every two months by starting the hybrid system for about 30 minutes*. Check that the "ready" light is on and all lights and electrical accessories are off. As with the auxiliary battery charging, it is not necessary to drive the vehicle, but the steps to prevent exhaust buildup must be taken."

From the above it seems the traction battery will be ok but the 12V battery needs to be every two weeks. I have left my corolla cross for around 5 weeks and it started ok though.

The battery is quite small and 3 months might be a big ask for it to hold enough charge to fire up the car. I would contact the dealer who services the car and ask.

I just read my owners manual and it indicates you need to disconnect the earth cable if your going to charge the battery with a charger. This may become problematic if you have a power operated tail gate, you may be able to access the battery via the back though with the rear door closed?

There are some items that may not work correctly when you reconnect the battery at first, check your owners manual.

Does it have a normal lead/acid starting battery, if so maybe a maintenance charger on that might be good . I presume the main battery would be some sort of lithium so would sit fine for a few months provided nothing is draining it at all.

Thanks everyone for your helpful feedback on this. Looks like short periods of trickle charge on the 12V battery via a timer might be the best option.

I'd take advice from someone that has actually read the vehicle specific manual, the hybrid setup can vary markedly, so I doubt there is a one size fits all. I'd imagine that the 12V starter battery would be prioritised and the drive battery has way more capacity than the starter battery, so should be more than adequate.
I wouldn't really count 3 months as long term storage, charge it to 2/3rds, fill the tank with fuel and look the door. I'm sure it will be fine.

On my vehicle you can park it long term and it goes to sleep mode. If the starter battery charge drops from parasitic load, then it charges from the drive battery. If the drive battery gets low, then the vehicle may start the ICE motor and pump electrons into both batteries and then shut down again.
If that all runs out, then getting it to wake up again can be a bit of work.

Do you not have a friend or family member who can take the car out for a drive once every 2-3 weeks to keep everything charged up and moving?