Maintaining Battery during dormancy

When off, the hybrid battery is isolated from the rest of the car.
They typically don’t lose much energy, but the older they are, the more prone to it.

there is a constant drain on the 12v, again, the older it is, the more likely to drain and sulphate.
In good health, it should last more than a few weeks, but becomes more risky as it ages.
A maintainer is always best, but disconnecting also works. But you may lose a few settings like radio stations or window memory, it’s inconsistent

 

I don't think there's a need to cycle that maintainer manually.

 

correct, it does all the switching itself. when not charging, it is monitoring charge level. you don't want to switch it off

 

All vehicles "burn" power when off. A Prius with no aftermarket gizmos has 15-25 ma of parasitic draw. That is 15 thousands of a amp. Many trucks have close to 50 ma of parasitic drain.

With a new 12v battery you might get 4 weeks before you can't get a Ready. With an 8 year old battery you might get 4 days. The truck has gone through 2 batteries in 8 years. I had a Prius 12v battery last 10 years as have others so its no surprise its dead after a week trip.

 

Allowing it to discharge dramatically reduces battery life. Great if you are helping Priuscamper.

 

That's what these new-fangled battery maintainers do. They're smart. Not an old-fashioned dumb 'trickle' charger, so no worries about over charging. Read the link on the NOCO1 you provided above. It's for the 12v battery only.

As far as the traction battery goes, on your 2010 or on my 2026, I've got no idea. It does lose charge, as @bisco said. Perhaps scouring the threads will give you an idea how long it can remain unattended. If it goes totally dead, I THINK there's no return.

 

If you have someone that could drive it for a few miles once a week would be good.

 

For the 12 volt I'm using a smart charger, rated 4.3 amps, pretty much constantly. If we drive one day, I pop the hood when we get home, plug it in the next morning, it stays thus until the next time we drive. Parked at an airport, for more than a few days, I would disconnect the 12 volt. Apparently that can be done under the hood, the fat, white wire in the fuse box is pulled, IIRC. @ChapmanF I believe shared that tip?

The Owner's Manual say that the hybrid battery is ok for "several" months down time:

 

What could happen to the rest of the car if the hybrid battery was disconnected for 1-2 months?

 

Nothing, it’s already disconnected when off

 

It’s not magic, just software logic.
If you’re concerned about a fire, you’ve already got a high voltage car in the garage.
Regardless, you can keep switching it, but it does hurt the battery life to discharge. They prefer to be topped up all the time unless lithium

 

Our 2010 has spent at least half it's life on a CTEK charger; I installed the current battery in September of 2015. It's still testing like new.

 

Not that I’m aware of. Look into the prolong charger. I don’t think you can use it like that, but I could be wrong

 

There are grid chargers and they only top off the battery. They are also quite expensive. What they won't do is restore the capacity through repeated cycling.

 

Unless you're mothballing for more than a couple of months, fugedgabout the hybrid battery. For the 12 volt battery, connect it to a decent-quality smart charger for the 12 volt battery, at the commencement of the downtime, and just leave it connected.

As alluded to by @rjparker, only activating the 12 charger for a few days at the end of multiple week hiatus, could be it's demise.

 

You could always just disconnect the negative cable of the 12v battery.
It will hold the charge for several months.
Just write down your radio stations. And your trip miles, if you keep track of mileage.

Then just connect it when you return. Remember, the rear deck is electric. So either leave something
across the latch so it doesn't latch shut, or you'll have to climb through the back and remove the small
panel to release the trunk lid to reconnect the battery.

You could disconnect the white cable in the fuse box in the engine compartment. Don't let it touch ground!!!