Three week storage recommendations?

I would just go by Toyota recommendation for traction battery: If there is EV estimate left, drive it until it switches to HV mode and shut off. As for the 12V battery - no action needed during 3 weeks for a new battery.

I agree with the ~5.7 kWh available for EV, my assumption is that it is from 85% SOC down to 20%. Maybe someone will check it with an external device soon.

 

Make sure OP knows that you are referring to the big traction battery, not the little 12V battery.

If anything, consider topping up the 12V battery with a bench recharger (in the car is OK, no need to pull out the 12V out to the bench) before leaving. I can't speak for the Prime, but prior Prius generations are known to not charge this up very well in many common user scenarios, especially with short trips. But this advice will be more meaningful a few years down the road, when the 12V is aged and weaker.

 

keep in mind that toyota has upgraded the 12 volt capacity in the gen 4, and moved it under the hood.

 

No plug ins. Just regular Prii. They use to say leaving the regular Prius too long was bad because it was searching for the FOB.

Never mind.

 

sorry, i thought you were referring to the hybrid battery.

 

"If anything, consider topping up the 12V battery with a bench recharger"
Again, not for just 3 weeks. 3 months, yeah. Also, no need for the neighbor to drive the other car during a 3 week lay over.

 

If you've got a good quality, appropriate smart charger, I would not hesitate to hook it up for the duration. It may or may not survive that long without problem, but it'll certainly take some hit, sitting that long: there's constant light current draw. If you have a secure garage, there is no downside to hooking up the charger.

 

Likely true.......unless the power lines are struck by lightening while you are gone. And it is THAT time of year.

Once the doors are all closed and the FOBs are nowhere nearby, after about 30 minutes the current draw goes WAY down.

If everything is operating normally, 3 weeks should NOT be a problem.
If everything is not operating normally........maybe that would be a good time to find that out.

 

When new, yes. But as the battery gets older, and particularly with Gen2 and Gen3 models in use patterns that don't fully recharge the 12V, then the shorter the interval that needs attention. E.g. right now, I'd be quite unsurprised if my five year old battery was dead at 4 weeks if inactive, and quite surprised if it was alive at 8 weeks, without some prior attention.

I'd hope that Toyota improved this in Gen4, but haven't seen the feedback to confirm it.

 

Just for reference, our 2010 has a steady, background draw of 15~20 milliamperes.

 

That makes 11 to 15 Amp-Hours per month. That puts an aging battery at risk fairly quickly, especially when it starts without a full charge.

 

If I monitor voltage daily, when the car is idled, it slowly but surely drops, sort-of settles in around 12.5 ish. But I don't like this, and it's common for our car to sit multiple days, and then it might be just a short milk-run, as often as not. So I just keep it hooked up, automotive life-support.

 

pretty sure the gen 4 battery is larger, they put it under the hood. also, i believe they added a timer to the interior lighting.

 

i'm sure it is fine, what were you expecting?

 

We often travel for more than two months. Looks like the traction battery will be fine. On our other car we use a battery tender while we are gone. It ensures that our car will start when we come home. As I understand it, the 12v battery isn't used to start the car. So we come home after a long trip, the 12v battery is depleted and the traction battery is at 50 or more per cent, should I be concerned? Looks like the car will go, batteries will be charged, and there is no problem. Am I right?

 

No.

If the 12V battery is depleted, the computers won't power up and the car won't start.

 

The 12V battery is not used to crank up the gasoline engine, the traction battery and attached hybrid system do that.

But the 12V battery is required to boot up the computers and make ready to connect the traction battery to the hybrid system. So when the 12V is dead, the car is dead.

 

What they said.
Plus......the 12 V battery doesn't really have to be completely "dead" to screw things up.
Something below 10 Volts can cause the computers to malfunction.

 

Thanks for your replies. Looks like I will continue to use the battery tender when we are travelling.