Will park at LAX for 13 days. Dead battery for sure?

As long as cars use batteries, some owners will experience dead batteries. A small number of failed batteries does not necessarily indicate a general problem. Lead-acid batteries are easily damaged by abuse. The lead-acid batteries in Prius are smaller than most, and can be easily drained by headlamps or interior lighting. Even when not abused, their service life is only about four years. Once a battery is nearly dead, sitting for a few days can finish it off.

Tom

 

It is, and it isn't: Because of the tiny size of the 12-volt battery in the Prius, Toyota put out a warning, so people could not say that they were not warned. In addition, on the 2010 they automatically disable SKS after a short period. But the warnings are overly cautious. The car can actually sit for a considerable time and still start up just fine. As I've said before, I've left mine for a month at a time more than once, while traveling.

Also noteworthy is that it takes almost no juice at all to jump-start the Prius, since the external source does not need to turn a starter motor; it only needs to boot the computer, which in turn will throw a relay to bring the traction battery on-line. From that point, the DC-DC converter will supply the 12-volt power, and the traction battery supplies the power to MG1 to start the engine.

Lead-acid batteries have limited life. After a few years they must be replaced. Near the end of their life, they will run down more easily. But the only cases I've noted where someone reported failure to start, it was either a computer problem, or they had left lights on, or a door ajar, or had run out of gasoline. There is consistent experience that the car can sit for a month and still will start just fine. And on the 2010 you don't even have to worry about leaving the SKS on.

 

Amen. case in point, a few months ago i come home from work, SO is doing deep clean of car, inside and out. our son is playing in car the whole time, turning dome lights on and off, etc.

i told SO that she had better start car and drive around a bit to recharge 12 volt battery...she said ok, went in started dinner, never started car.

next day she calls me. car "acting weird" i asked if she had recharged battery, she said no. so i had to leave work, go home, put jump box on car start it and off she went.

told her that every time she runs battery down that low, its taking 6 months off its life.

a lot of people question me when i sit in parking lots with the car "running" instead of turning it off, etc. the reason is simple.

the weak spot on the Pri design is the failure to provide a boost to the 12 volt battery ALL THE TIME. granted, running SOC below the "safe" level would be foolish, but at the same time, the 12 volt battery is just as critical for operation. now there is a balance between cost, safety, and simple human stupidity.

12 volt batteries mostly die due to the latter but they still have drawbacks. they cannot sit very long under any circumstances and the weaker the battery, the quicker it will drain a charge even if nothing is feeding on it.

so, without a reasonable solution to the design, i simply leave the car running so the 12 volt battery stays at 14 volts. frequently at lunch, i will go out sit in car, make phone calls, listen to radio, etc. i usually do not start the car, because it would have to run to warm up first. i sit there and watch my 12 volt battery charge slowly dissipate. i wont let it go below 11.5 volts which is what i consider the minimally "max safe" level.

but my battery is new and has never been run down. i can go an hour easily on acc mode with no issues. my SPM is a different story. its batttery is older, been run down more etc.

for one thing, its resting voltage after being charged will be lower. its voltage will drop quicker, i have much shorter time on acc mode , etc. all that comes with age and abuse. lead acid batteries are designed to put out a high current for a very short period of time and work best if charge level is topped off.

 

Is there some built-in way to monitor the 12v battery voltage in the 2010?

Or, does one need to connect a $5 VOM (voltmeter) to the cig. lighter socket?

Thanks

 

i use scangauge. i also grill block and although i am confident that i can block 100% with complete safety, i feel better monitoring water temps anyway

 

Does beg the question of why is there a 12V battery to begin with?

 

cheap, isolated way to provide power in a very safe way

 

Let's have a poll and see all these folks who are having a problem...
:rockon:

 

The response is deafening....
And yes, just as I predicted, my Prius started up like a charm after three weeks left idle.

 

That's the final nail in the coffin.

It's settled then. Problem's a myth.

 

What you say may be true. But in my 2001 Prius I would always turn it off when I sat in it and listened to the radio. Many times. Only once did the 12v battery go dead (door left open). The car was almost 9 years old with the original 12v battery when I sold it a month ago.

3PriusMike

 

Hi Folks...my neighbour left his Gen1 Prius for 2 weeks whilst out of the country and the battery ran down. It was probably because it was on its original battery. He's had no other problems since buying the car in 2001, and none since the flat battery episode (not sure if he changed the battery...i expect so). I have a Gen3 and having read the handbook entry relating to this issue, re SKS auto-disabling, i'm sure we have nothing to worry about. So whilst not a myth, i would think the problem has now been sorted.

My first post on this site...lots of great info here...many thanks!

Cheers, Rich

 

Actually, you are missing the point. SOME owners will have battery problems, just as SOME owners will have flat tires, and SOME owners will have failed inverters, and SOME owners will get into accidents, and ... Doesn't mean there is a design flaw involved with each incident.

For that matter, I bet there are dozens of dead batteries in non-Prius vehicles this morning in my area (first cold spell of the season). Does that mean that all cars are mis-designed? Surely it can't be a myth as long as SOME cars have dead batteries, right?

Get the point? Just because several people post, "I did nothing wrong and my 12V battery was dead after a week of not driving" doesn't mean there's any kind of problem with the car's design. Some of those people were just unlucky battery-wise, and happened to fall on the early side of the failure curve. Some had misused their battery and shortened its life -- perhaps not realizing it. Some had other problems that drained the battery that they have not yet figured out.

The original title of this thread is "Dead battery for sure?", and the myth is that there is a design flaw in the Prius that leads to 12V batteries dying if you let the car sit for a week or two. That is a myth.

That does not mean that batteries don't die in Priuses. It does mean that the people who are now worried about their batter dying and are wondering how to disable the SKS and how much trouble they'll have if they disconnect the 12V for 2 weeks, and ... are doing so because of a myth that's arisen in threads like this.

 

Amen!

 

Would one of those gadgets that connect to the positive side of the 12V battery and disconnects it below a certain voltage threshold work? Also, does anyone know why you are not supposed to jump directly to the 12V battery, or is the connection post in the engine compartment just a "convenience"?

 

No need to be defensive there.

I don't think anyone of us can categorically say there is a design problem or none in the 12V battery/charging system which is smaller than normal 12V batteries and proprietary, that we know for a fact.

If a mere 1 percent of the batteries are marginal and leave their owners stranded, would that be considered a design issue ?

 

And if .769% of hair dryers stop heating in the first 2 months - would that be considered a design issue???

And what about 2.57% of potato chips being cracked when you open the bag?

 

No need to be defensive there. It's just a car.

A small battery with low reserve means it can be drained quickly.
Is the Prius 12V battery undersized ?

 

Interesting tactic. Whenever someone brings up a point you don't want to address, just ask them why they're being so defensive. Certainly is much easier than actually addressing their point.

 

We just came back from 14 days in Hawaii and our 2007 gen II that we left at the airport had no problem starting. In fact our other 2005 gen II left at home started with no issues after 16 days. No special prep. Car just keeps going.

Bye the way the trip was great.