long term (four month) storage

A Prius needs to be driven every week to avoid high voltage battery degradation. Especially important on an older hv battery. Driving avoids flat spotting tires and keeps the 12v charged. The engine will stay lubed and rodents are less likely to set up a household and chew your wires. Disconnecting the 12v will make it hard to get into the hatch to reconnect since there is no hatch key.

There is no useful storage strategy for the hv battery since internal contactors automatically disconnect it when the car is off. The tires could be overinflated to their max rating to reduce flat spotting. The 12v could be 98% disconnected in the engine fuse box by disconnecting the top white cable. No useful solution for engine lubing in storage or for rodents.

Your choice.

 

If you're only asking about the 12v ? I do with trickle. It may help that one possible issue for the long hibernation period. I heard that some car company dealers have been instructed to charge high voltage hybrid batteries in the NEW cars once a month.
Using an app like DrPrius or Hybrid Assistant before you leave and after you return for documentation could help if you have problems with the car when you get back. Not to mention all the other helpful information the apps can provide.

 

Yeah a drive around the two month mark might comply with this (page 30) Owner's Manual guidance:



For the 12 volt, disconnecting the neg cable, it'd be good for 4 months, if it was in good condition at the outset. Or a smart charger, something around 3~4 amps rating. Owner's Manual excerpt:



I use a CTEK which is 4.3 amp rating if I'm not mistaken. Our usage is quite low, sometimes just once a week or so. A charger like this can be left on long term.

Other things you might want to do before leaving:

Fill the gas tank
Change the oil
Wash the car
Raise tire pressures to max side wall

 

Do he have any college friends that does long joy rides?

 

You should buy a tender type small charger and leave it connected.
You should NOT get a cheap trickle charger as that might do more harm than good.

 

I'm a bit surprised at hearing that from you because...........I believe it is NOT true of the type of batteries used for the HV.
Unless maybe it is really old or is left in a really dead condition.
And certainly NOT in only 4 months, which is not really considered to be "long term".

 

Yep..absolutely. The 'Battery Minder' brand works great. Use them frequently on ALL our vehicles to keep the 12V batteries in good contrition.

 

Its an eight year old battery. Plus four other reasons as listed. Simple driving will keep the hv battery at its current capacity. Capacity lost due to four months of inactivity is lost.

 

But what evidence do you have that it will lose ANY capacity with 4 months of inactivity ?

It's age might be a clue but not a given.

It also is not a given that being driven regularly will ensure that it stays healthy.
It might fail tomorrow.

 

Can't fix stupid is a catchy signature.

 

It is. Some people invent their own rules and tell everyone it is gospel. I'd go with the advice from Toyota that Mendel Leisk quoted and personally I wouldn't even worry.

 

It's wise to be proactive. I hate it when I'm a crash test dummy

 

We have two 2010 Prii. One with about 70,000 miles and one with about 32,000 miles. Both have been repeatedly stored for six months plus several times with no ill-effects. I try to park the vehicles with the drive batteries a close to full charge. Stabil is put in the fuel tanks and the engine runs enough to distribute the fuel through the entire system. The 12-volt batteries are sometimes disconnected and always left on a battery maintainer. I have been having excellent luck with Viking battery maintainers from Harbor Freight. When on sale they are about $25.

 

Which model would that be ?
The one nearest to the price is about $37.

I am glad to see that they finally got another brand to compete with the cheap Cen-Tech crap which used to be all that they had.

 

The CTEK's likely ARE made by Vikings, well, their descendants. But the prices have gone through the roof lately, not sure what's with that.

Our garage queen is hooked up to one, pretty much 'round the clock.

Addendum: N'mind, see they're made in China now.

 

Be careful here.
CTEK is a respectable brand.
CEN-TECH is NOT.

CTEK has been around for a long time, I think.
CEN-TECH is a Chinese knock-off.
I think the name similarity is not a mistake but part of the knock-off play book.

 

Can you confirm that you use this on a Prius? I have a 2019 and will be leaving for 5-6 months & someone recommended the tender. Where do you connect this on the Prius? Thank you in advance for your guidance --

 

If I were you I'd just find someone you know to come over and drive it once a month to the grocery store. Then you dont have to worry. No need to get bogged down in the technicalities.

If you really cant do that it seems like it would be better than nothing to ask your nephew to start it up and leave it idling for 15-30 minutes once a month. Then at least the ICE would charge the HV battery if it was going dead.

 

Unless maybe it is 30 miles to the grocery store......neither of those are recommended.
It should not be started if it can't be driven.