12volt battery discarged on Prius

I haven't checked my Prius in awhile, but last time I did so was in Park, in Ready mode. Popped the hatch, used a Fluke 177 on the battery. Had a reading of 13.9 vdc

In contrast, my FJ Cruiser will idle at 14.6 vdc

 

Just out of curiosity, what is the life of a 12v battery supposed to be? I mean, the battery in my Olds died after five years (and five incredibly cold winters), so I'm assuming the life of the 12v to be close to that...

 

Automotive Diagnostic Tools

I read your post.There is a battery protection circuit that prevents the car from starting when 12volt battery is running low. He says, just touch the 12volt terminals with a jumpstart cable. That works, though you got to have a jumpstart available.

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nothing stops the car from trying to start with a low battery.. it simply doesn't start. it light up everything it can untill it runs out of enough juice to switch any more computers on.

somtimes this makes an odd ticking noise

 

Battery is buggered
it happens
ask dealer to replace crook battery under warranty.

 

Has anyone here found that the high voltage battery has drained some after leaving the car parked for an 8 hour or more period? This has happened to me a few times now, and I am baffled...I've parked the car with a good SOC, turned it fully off, then started it up later and the SOC is down 3 or 4 bars on the MFD. I'm suspecting the SKS, however, I'm still not sure...It's not a daily occurence, but I've noticed a pattern. It only happens when the SKS is in close proximity to the car.

 

Temperature and if the battery has had a big surge of charge it may read high and settle over time. Wouldn't be any draw on it at all unless the main relays are closed which requires on or ready mode.

 

Re: Automotive Diagnostic Tools

You know, I was trying to beleive this, too. Now, I just think they talk about the hybrid battery protection. The 12volt battery drains down to 0 , I have seen it down at 4volts.
This makes it highly unlinkely, that the 12Volt battery is protected from exceed drainage. Just the fact that you need a jumpstart, tells me the opposite.

frosh

 

With the Battery Minder on my Prius, I'm hoping a lot longer than that. From the reports here, I'm guessing 3-4 years.

 

Re: Automotive Diagnostic Tools

None that I am aware of. If a driver leaves a door ajar - especially the rear hatch - the 12 vdc battery will run down. Period. A boost from another car, or a charger set at 10 amps, will bring it back to life

Once the 12 vdc battery has been discharged, it really is best to remove the battery and properly charge it with an automatic battery charger set at 10 amp

 

When the car is powered off, the NiMH traction battery is out of the loop. The HV relays are open and there is no current flow out of the traction battery

The most I have seen is 2 bar change in SOC. This was in extreme summer heat, went to a restaurant with some co-workers, went back to the car 2 hours later. Car was an oven inside, perhaps that was why the SOC changed

Otherwise, if I park it with 4 bars indicated SOC, I can return in a day or a week and still have 4 bars indicated SOC

As our Grumpy Old Moderator (tm) (c) indicated, there is a large hysteresis involved with the displayed SOC. This is no different than the "dead band" built into a lot of factory gauges

For example, according to the shop manual for the 2000 GMC Sierra I used to own, at "normal" operating temps the coolant gauge had a 30 degree F deadband

 

Re: Automotive Diagnostic Tools

This is probably very significant. Lead acid batteries are considered completely depleted at ~9.6-10.5 volts depending on who you ask, the load condition, and the exact battery in question. Below that the chemical reaction that creates the electric charge takes a left turn and starts down a non-reversible path. This can really kill a battery, even one thats almost new. Some of this can be reversed with a special charging routine, but that is almost certainly beyond what the built in dc:dc converter does. Anytime the battery is discharged this low, it really probably should be pulled and run through a special charger to undo as much of the damage as possible. This is probably an even better reason to look into an auto disconnect device. Even if it doesn't actually let you start the car, it would keep you from doing serious damage to the battery.

Rob

 

I would hope a LOT longer than that. It has very light duty since it doesn't have to crank a starter motor. I've generally gotten about 4 years in prior cars and the first time they fail to work properly is always in the winter when the battery is least efficient. I expect the battery in my fob to die first

 

It did it again!!! Yesterday I dropped the car off at the valet in the Helena where I park for work, nearly a full SOC on the hybrid battery, then when I picked the car up 9 hours later and started it up, the SOC was down to 2 purple bars!

Will the hybrid battery drain if the car is left in park and not turned off? Did the fact that my SKS key fob was within 5 feet of the car on the valet board do this?

This is really weird people...any help would be appreciated. Originally I thought it was the Scangauge, so I returned it. Obviously, it's not...

 

Did the valet leave the car running? People have done that before.

If you leave the Prius in park, the ICE will run as needed to keep the traction battery charged.

Tom

 

Or did the valet press the power button two or 3 times with his foot off the brake when parking which would leave accessories on and run down the battery.

 

darn that means my 12 volt battery is done, everytime i start it up i get red triangle before ready mode, plus i can hardly run accessories.

 

The valet is not shutting off the car properly. You've been lucky so far: they've been leaving it ON and all you're doing is burning some gas while it's parked. Some day they will leave it in ACC or IG-ON and one of the batteries will get drained. That will be bad.