Prius 12V Battery went dead in 20 hours, Fob key won't unlock door

i could study that to death and still have no idea. white to bright, black to brass, served me for 40 years.

 

Yeah, for example: I've orbited the sun 65 times without fully comprehending the electrons in an automotive battery flow from the negative post, to positive.

I had a contrarian inkling that might be the case, but no more.

A puzzle: thought I'd clean up the posts and clamps on ours, and while completely disconnected (I had a memory saver strategy in place) the battery measured 12.94. After reconnection: 12.61. Some "overhead"? Who knows.

 

is that the 'surface charge' we hear bandied about?

 

Disconnected reading was with my solar ba5 tester, connected with my regular (Milwaukee RMS) multimeter. I've never seen disparity between the two in past though. Not charged for a. couple of days, car well driven too.

Not sure.

 

Same here - I'll read it later.

But I have had (at least) 2 older cars ('70s) where there wasn't a ground to both the Engine Block and Chassis.

Short answer - I tested the voltage on one between Chassis & Engine Block when starter motor was engaged. Almost 2 volts. Added a Chassis to Block cable. The car started so much easier in one case, in the other, the headlights didn't dim with the A/C cycling.

Haven't looked at PRIUS, but I suspect all newer cars would have licked that problem.

 

I am sure the Prius is OK. MG1 starts the engine. It also uses the running engine to charge the traction battery. I am sure there I a healthy ground connection for that.

 

I have heard that some countries only change the vehicle model year when there are significant changes. You just bought a 2016 Prius but in the US, the current model is designated as a 2017 Prius.

My 2017 I purchased last October was manufactured in September as. 2017 Prius. I assumed you had your 2016 for several months already.

 

That's Australia. It's a Gen 4 PRIUS. No big deal about whether it's a 2016/2017, other than for the age of the vehicle at sale - the build date on the placard will show what month/year it was built.

And, as far as I can see, there were no changes between 2016 & 2017.

We've always done that - we'd generally have distinctly different (with a few exceptions) models of our local-grown cars, often spanning a couple of years, and released at any time of the year, not as a "196*" model. When the Japanese/Koreans came here, they followed the local's lead. Now the locals are (almost) dead.

 

In my country..cars are imported directly from Japan. The car i received in May 2017 was manufactured in October 2016 if i didnt remember wrongly.

 

Same for UK. It's a Gen 4 + yyyy.

 

I don't know, but I don't think that the traction battery would be grounded to the chassis or the engine, but would be isolated for safety. It most likely has HV (220-600 ?) positive and HV negative cables to the MGs and inverter. I think the inverter would be the source for the 12v side of things with a connection to chassis/engine ground from there and the 12v battery.

 

Back to the topic of the battery being dead..

1st instance..car was parked for about 32 hours..i did go to the car to take some stuff after parking it for about 18 hours..door opened as normal..

but when i wanted to start the car after 32 hours..door didnt unlock as per normal when i approached it. Called for help..my colleague came around, once the jumper cables are connected..vehicle alarm sounded and vehicle started. That was about 2 weeks after getting the car.

2nd instance..car was parked for about 21 hours..

3rd instance..car was parked for slightly less than 12 hours..

What i have installed? A mcintosh amplifier..a TPMS system...scuff plates with LED lights...as well as a rpm meter. (Dash cams were already disconnected)

When i lock the vehicle, i always turn around to ensure cabin lights (changed to LED ones)..head lights and DRLs and fog lights are off..

Questions
Someone mentioned that the 12v battery is not charged by an alternator.How does it charge then? Is it constantly charging?

When i went for my servicing,the technicians tested the battery and the result slip showed that the battery is 100% working but only 70% charged. Which likely means that it is working perfectly but not in a state of full charge.

Amplifier is shut off when engine is killed.It probably draws quite a current when it is on..but at the same time the 12v battery should be charging right?

I will be removing the amplifier soon to see whether it is really the cause of it..wish me luck.

 

Good luck chasing that down. I would disconnect all changes from stock and put it back like it was. Something is draining the 12v while the system is off.

The Prius has no alternator. Just think. The engine stops practically whenever the car isn't moving and lots of other times. An alternator would be useless unless it was electrically driven like the air conditioner. But a spinning alternator is way more inefficient than a solid state, no-moving-parts charger. The DC/DC converter in the hybrid inverter keeps the 12v battery charged any time the system is in "READY" mode. To see it at work, put a multi meter on the battery terminals with the car off and read the voltage. Then put it in "READY" (foot on brake and hit "START). Watch the voltage at the 12v terminals jump from 12.XX to 14.XX volts.

 

The maximum i get is 13.7 volts from the rpm cum voltmeter connected to the OBD port

 

I would do a couple of things:

1. Find out where your battery is at. Check it with something like a Solar BA5, or drop by a battery retailer, they'll likely do free testing with a pro-level tester. Or dealership, for a nominal charge.

2. Assuming it's got some life, get a decent smart charger (something around 4 amp max, capable of running a charging regimen, and then be left on indefinitely if needed), use it periodically if the car sees regular, daily use. Or leave it hooked up constantly, if the car's idle for multiple days at a time, and often is just seeing light use.

That's likely meaningless, a reading taken while the car's on.

 

It's a Gen 4. The 12 volt battery is under the hood (bonnet).

 

When I say "where it's at" I mean status wise, LOL. And I think he's found his battery by now. If not, fugedaboutit.

Man we're butting heads this AM.

 

Seems like I am too literal today.
I've been away from Canada too long, I guess.

 

And I'm curmudgeon personified: got up too early I guess.

 

It is a bad battery. The 12 volt battery in a new prius should be a deep cycle battery, like a trolling motor battery. They do not short out as often. If a battery well not hold a charge it is bad. I donot care what the the "experts" say.