My 12V Battery is dying

Best get your own jump pack. I’d look into 12 volt smart charger as well, if practical: available 120 volt AC outlets nearby, in a garage. If driveway parked, there are more secure on-board chargers; you typically just run the charger’s power cord out through the front grill.

 

Mostly as a thought experiment, rather than for real, since I have a garage with power, and don't park my car at an airport for month long trips.

Is there a fuse you could pull to eliminate standby power draw? I read of a Dome fuse, but don't know if that's it.

What do they do for the month-long voyage from Japan to the East Coast? Something under the hood, I imagine, unless the hatch was blocked open, and I'd think they'd want to keep the car buttoned up.

I think I've read of an under hood procedure for that on the forum. I'll have to search for it, but I think there may be some disassembly required.

And, what do they do about the initializations found at the back of the manual? Would that be done at the port as part of the prep? Or maybe not a big deal.

 

I just ordered a NOCO GB40 to have available when needed, still curious about the manual rear hatch operation though.

KH

 

If you hooked it up under the hood, you'd be able to open the hatch electrically, I imagine.

 

I ordered one of those NOCOs as well. It comes with an AUX cigarette lighter adapter - can you charge the 12V car battery using this adapter? Can I use the trickle charger and AUX adapter to charge the 12V car battery?

 

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No, I believe the cigarette lighter is disabled. It's turned-Off with the rest of the car so no power will be getting to the battery. You'll need to double check that. OEM has been doing this for at least a decade.
If you want a quick full-proof method of hooking-up; you can install a capped weather-proof cigarette lighter pigtail connector under the hood. Then you can use that aux. adapter.
Make sure you firmly bolt-down that pig-tail. I'm assuming you would do this for the convenience and safety of it popping loose if you forget to unplug it. I've done the same on my camping pickup with a 20A inline fuse. Not for jump starting, but to recharge and power small accessories like cell phones. I also use that port to keep a trickle charger on it, doesn't get driven much in the winter. Got a jump pack as backup; which nobody touches, if that big marine battery should get discharged to a point that the truck won't start.

 

With the negative cable to the battery disconnected, could the hatch be opened if a battery jump pack was connected to the under hood connection points? What would happen if the start button was pushed? Smoke?

 

yes

Not sure about gen 5, but from earlier-model experience, if the jump pack was able to supply enough juice (90 amp seconds or so), the car would go READY and you could drive it around. Otherwise, it wouldn't. There wouldn't be smoke. There might be DTCs about battery-state sensors.

 

Smoke would be dependent on how well that jump pack was engineered and safety cut-offs - both physical and software.

 

True, some jump packs advise you sternly to disconnect the pack soon once the beneficiary vehicle has started, so the pack isn't damaged by the vehicle's own higher charging voltage. That would be no different using the pack on a Prius than on anything else; you'd want to unhook the pack soon after seeing the READY light, and before driving the Prius around.

The main thing you'd notice, with the pack and the battery disconnected, would be when you're done driving around and you push the power button to shut the car off. The result then is instant blackout, rather than the usual controlled shutdown.

 

So, perhaps, one could disconnect the negative terminal in the trunk and close the hatch, and leave for a while.
Then, on return, open door with mechanical key, pop the hood, attach jump back, and then open hatch via fob?
No crawling around required? No Ready Button Status involved?

 

makes sense to me

 

Wow. Cool. You could actually drive without any battery connected.

 

That was one of the reasons I got the jump pack, to make sure we could open the rear hatch even if we couldn't use the start button or make the hybrid system "ready". Still, I challenge anyone to try and open the hatch using the manual release lever and report back how they did it.

KH

 

It takes me a while to get limber enough to move around after sitting awhile, lol.

 

Old-school advice was to never ever do that, because the type of voltage regulation used with conventional alternators used to strongly depend on a battery in the circuit; other stuff in the car would be subjected to wild voltages if the battery weren't there.

The DC/DC converter in a Prius is a lot more like a modern computer power supply; if it wants to put out 14.7 volts it'll put that out reliably whether the battery's there or not.

It might still not be an excellent idea. It might set some trouble codes about the battery-state monitoring and, dependent on the generation, those trouble codes might come with fail-safe behaviors that limit your driving.

 

The dealership is "on the hook" to make sure that safety feature is working properly. I'd ask them to fix it before your 3 year 36K mile warranty expires. If they refuse, a call to corporate, local consumer advocate, and NTSB would be warranted. Even if your just beyond your mileage warranty, NTSB doesn't take kindly to fake safety equipment....

Just my two cents.......

 

You didn't mention a screwdriver to loosen a screw. Looks like a Phillips.

 

Yes, I know the procedure. I read all the steps, watched the video, and still couldn't do it. Thus I'm asking if anyone else has done it and what is the technique that works. Or maybe I am just too old.

KH