2 month storage

See page 133 of your manual that says

"Leave a low level of charge in the hybrid battery (traction battery) when
leaving the vehicle undriven for a long period of time.

After confirming that EV mode has switched to HV mode, turn the power
switch off."

Also hybrids do system checks, etc when you are not driving them so the 12V battery will still go down some over time. If you can charge it to full before leaving it or use a battery minder while gone, it would help.

 

pump up the tires to max sidewall pressure

 

I would leave the charge around 50% and disconnect the 12V battery. From my past experiences with EV and PHEV, the 12V battery is really weak. If you leave your car off for that length of period, your 12V battery will probably be dead when you restart your car.

 

+1

Leave 50% of charge and disconnect 12v battery.

 

No it won't.

IF.....it is fully charged going in.
AND.....the battery is not already worn out.

Since your model might not use much gas in normal use, some fuel stabilizer might be a good idea.

But NOTHING else is really required except being sure the 12 V is charged up.
A battery tender is OK but should not be needed.

 

I have a storage issue, too. My wife and I were out of the town for 44 days during the recent holidays. Upon return, the traction battery of our 2018 Toyota Prius Prime was fully charged but I failed to check the auxiliary battery. Following a near-by trip, the car failed to start. I'm sure that the auxiliary battery suffered from a normal discharge condition during our absence. A simple jump start and subsequent battery charge at 4 amps returned the car back to normal operation. The next time, I will automatically charge the storage battery on the Prime (which I did with my other Toyotas) upon returning home. I also now carry a small lithium-ion battery charger from Costco in the trunk.

My question: Should not the DC-to-DC Converter have charged the low voltage auxiliary battery, even though I had operated the car on EV and the engine never ran? My Toyota Care Warranty is about to run out and I have a Toyota service date scheduled in February. Prius Prime owners need to be aware of the potential no-start situation when the car engine is not used for a month or more. Finally, would anyone suggest that there an electrical issue with the car which the Toyota technicians need to diagnose?

 

you are making several mistakes here.

1) you should not leave the hybrid battery fully charged for long periods of time (see the o/m)

2) just like any prius, you should either disconnect the 12v neg, or put a maintainer on it.

letting it run down, and then jumping it is not good for it's health. likely, it had just enough charge to start the car, but is damaged, and wouldn't take a charge while you were driving.
yes, the car does charge a healthy 12v when driving in ev.

 

Yeah.

Been there.
Done that.
Ten times on subs and too many to count on skimmer ships, company schools, other military excursions, etc.

Best Advice?
RTFM!
(read the.....ah.....'factory' manual.)

^ Do that.

DON'T do any of the goofy things you hear people try when parking a car for 60 days like putting it on jack stands, taking out the plugs and squirting oil into the cylinder bore, etc....
Also I would not disconnect the 12v battery (see above posts.)
Since having a <$100 jump pack (or at least a set of jumper cables and a 3-digit IQ) is as important as a spare tire, I really don't get wrapped around the axle about the possibility of a deav aux (12v) battery.

If yours dies while your car is parked for 60 days you did not cause a problem......you discovered a pre-existing problem.


Simply put....a car that cannot be parked for 60 days is not dependable enough to be a daily driver.

YMMV

 

^agreed
I imagine that a good portion of the Prime's sat on a dealer lot for over 60 days without movement before someone came along and drove/bought it. Ours was pretty dusty when we looked at it and may have never been test driven prior to us.

 

I often wondered about how long some of these Primes may have been sitting around and what impact it might have on the longevity of the battery packs.