Checking the 12v battery status on a 2010 model III

Well, MFD is the Multi Function Display, so they're talking about pressing the "DISP" button on the steering wheel.

 

You are not the only one this has happened to. I don't think anyone knows yet why some have the problem and others have left their cars for a month or more with no problem?

There is no button to turn off the SKS such as we had with the Gen2, the Gen3 is suppose to turn the SKS off automatically after some period of time, maybe 5 days or so. But even with the SKS on it should last way longer than 6 days.

The directions for checking battery Voltage you found appear to be for a Gen2. I'm not sure how to do it on the Gen 3, best way may be to use a meter or a ScanGauge. I think in your case it would be best to take the car back to the dealer and tell them what happened and ask them to to a test discharge on the battery. Don't be surprised if they tell you "Oh my, we have never heard of that problem before." some places tell everyone that.

How did you get the car started again?

There are some other topics on this subject, tried to post a link but for some reason it won't work. Try a search of Gen3 forums for "12V battery left stranded" etc.

 

I believe the above procedure will only work on a 2010 with a Nav, as you need somewhere for the Maintenance or Service Menu to display. The Info button referenced above is on the Nav and not on the MFD. The above procedure works on my 2010 III with Nav.

 

You can still check your 12V battery with a voltmeter. You can check it on the jumper tab in the fuse box in the engine compartment, between the jumper tab and an engine ground point. You can also check it on the battery posts. The 12V battery is in the cargo area, right hand side. There is a small cover that lifts up and exposes the battery.

 

I think that instruction is for gen2.

 

No offer of help here but.. Last week I pulled my III out of storage after over four months. Started just fine, Scangauge indicated 14.5v after startup.

 

This is significant, probably implies that there is something drawing more current in some cars than others when shut down. Or possibly some cars have battery or charger problems. There is a post in one of the other 12V battery topics that stated some European Prius were delivered with defective batteries.

Problem needs to be reported to Toyota. The statement that a Prius should not be left idle for 6 days is just BS by a service department that doesn't want to be bothered with a problem they don't understand.

 

Many on here (in other threads) have reported leaving their Prii at the airport or at home for between 2-4 weeks, with no problems.

Clearly, one of the following is a factor in the aformentioned:
(1) Defective battery (hey, it happens).
(2) Not charging.
(3) Significant current drain.

If I had to guess, it's either #1 or #3.

 

Note that if on going to "ready" the voltage is above 13.8 it's an indication the battery was discharged. The system ups the charge voltage of a low battery to get it to charge faster, then, once some charge gets in there it drops to 13.8, the "float charge" level.

Note further that these 12V batteries are deep discharge types, not intended for "vehicle starting", meaning max. current discharge of around 100 Amps. or less. Prius draws one or two 1/2 second pulses of about 50 Amps. to start. The traction battery actually starts the engine.

 

Is that true? I did not think that was the case.

 

Yes. MG1 spins the ICE to start it. MG1 gets its power from the traction battery.

This is the main reason that the 12V battery is much smaller than a normal car battery.

 

That being said, why can't you start the car if the 12v battery is low?

 

You need the 12V battery to close the relay(s) which applies voltage from the traction battery to the inverters and powers the car. The 12V battery also powers the computer that allows the relay to close if all the conditions are met. Not much power is required from the 12V battery but it needs to have enough power to supply a few things until the traction battery comes on line. As soon as the traction battery is connected to the car it supplies all of the 12V systems and charges the 12V battery.

 

Really? I thought all cars, hybrids and otherwise charged at something over 14 volts. My SGII has always shown a charge rate of either 14.6 or 14.7 when in Ready mode, at startup and after driving for hours straight.

 

Just this week, I returned to my car (in a parking deck) after leaving it for about 7 hours, and found the battery had died. My dealership had it towed up there, and they replaced the battery, saying it had a dead cell. The car is 10 months old. They said some batteries are just defective. I'm glad the dealership was helpful. I will say that towing it out of the tight parking deck was challenging--took two different types of tow trucks, one for inside the deck and then a flat bed truck. The tow truck driver took one look under the hood and quickly shut it. The mechanic at the dealership will show me how to use jumper cables on the car, should I ever need to.