long term storage: the facts

I have a 2010 Toyota Auris Hybrid as my vacation vehicle in Greece, which is the exact same platform as the 3rd gen Prius. The car sits for long periods, 8-16months at time, so I have dealt and worried about the HV traction battery, the 12v battery, how to open the trunk with the 12v out of the car, stale old gas etc. I wasn't able to find much concrete info in the past on the forums other than guesses. Well, now I feel I have some hard facts I want to share.

1. Do not worry about the HV traction battery. I have parked the car with either the 12v battery removed or the 12v in the car and connected to the CTEK XS 0.8 trickle charger, either way the HV battery never lost even a single bar of charge. Strange but true. I make sure to park it with a high state of charge, just to be on the safe side. The longest time I left the car parked was 16 months, which included one and a half cold winters. I am confident the HV battery can go 24-36 months with no issue.
2. I usually have the 12v battery removed from the trunk and plugged to the CTEK XS 0.8 trickle charger. This has worked great for years, until this year, the 7th year of the battery that came with the car. It finally got old and weak. I was able to get the car started, but it wouldn't allow for the doors/trunk to lock/unlock via the keyfob. I made the trip to a Toyota dealership to source the OEM 12v battery for the car, which is now made in Korea instead of made in Japan of the original from factory. It has the correct vent hole and fit perfectly. Satisfied, but it did set me back 149 euros plus VAT.
3. A word about stale gas. Do not worry about it. I was considering siphoning the gas out until I read it's not possible without some involved mechanical surgery. I talked to a mechanic who said to not worry about it unless the gas is 3+ years old. Indeed, after 16 months of sitting, the car started as if it was only parked for a day. wow. One word of caution though. One time I left the gas tank to near empty, and that was the time it started with difficulty and rough idle for 10-20 seconds, even though that time it only sat for 12 months. This time (16 months parked) it was 1/2 tank full, and started like a champ. This may have to do with quality of gas, so I will make a mental to put gas at my trusted gas station and have about 1/2 tank when I park it---this gives you a chance to immediately put some fresh gas on restart---after I start it from a prolonged period of storage, I immediately go to a gas station to top it off with fresh gas.
4. Opening the trunk without the battery in the car. Two options: either drop the rear seats and remove (with the help of a straight head screwdriver) the plastic cover that gives you access to the 5th door lock (you can then use the screwdriver head to flick the little arm to the other side to open the door) or you can connect the 12v battery that has been sitting in storage to the positive battery tab (in fuse box) and an unpainted chassis point, and now that the car has juice, with the keyfob in your pocket (assuming the keyfob has a fresh battery) you can depress the trunk button to open the trunk.

That's about it. If you have questions about long term storage, I have "hard" facts to share Reply to this thread.

Merry Christmas from Greece!

zebekias

 

I bought it used in 2014 with about 25,000km, and it's now at 42,000km.

 

I considered it but I have no experience with stabilizers. Do they work?

 

I don't know what happens at 200,000km but my first-hand experience tells me the NiMH HV battery is very very very robust. At 16 months of storage I might be a bit of an extreme case. The state of charge indicator didn't show any visible drop in charge, even when it was sitting for 16 months! Frankly it doesn't seem logical, but I can't argue with reality, I am reporting what I saw with my own eyes. For all those worrying about a 6-12 month period of storage, do not worry at all. Only worry about trickle charging of the 12v battery. Be prepared to get a new 12v battery after 3 to 7 years, depending on your luck, and local conditions.

 

I'd like to add that I have found the CTEK XS 0.8 ( XS 0.8 ) to work well. Eventually, after 7 years, my OEM 12v battery became too weak to reliably work, but that's to be expected and likely has nothing to do with the charger, which I recommend.

 

Gas stations Greece dispense 100% petrol. Blending with any ethanol is considered fraud, and there is no Ethanol label on the pump like there is in the USA (10% in Maryland)

 

I read about stabilizers from the article Johnny posted, it seems that most old gas problems may have to do with the ethanol in the gas. So if you are in a market with ethanol blend, you can try to source 100% petrol from somewhere, before long term storage.