Prius Won't Start

Thanks, good to know since I usually find it easier to pop the trunk than the hood.

 

Of course, if the 12V battery is really dead, then the electric hatch release will not operate. Then, if you are determined to jump the battery from the hatch, you'll have to crawl into the hatch area, remove the folding hatch floor, and find the mechanical latch release.

Or use the dedicated jumpstart terminal at the front of the car.

 

Speaking of this, what is the best way to test the health of the 12v battery? I have heard that it's such a weak battery to begin with that those handheld testers would not be useful since they give a cold-cranking amps reading, which doesn't really apply to the Prius?

Will just reading the voltage of it with a multimeter help me gain any visibility as to its health?

 

Reading the voltage will give you an indicator of the battery's state of charge. For an AGM battery, 100% charged is 12.9V while 0% charged is 11.8V. Obviously, the higher the voltage, the better. If the state of charge is low, put the battery on a charger overnight.

However the state of charge does not tell you the battery's capacity, or how much current it can deliver over a period of time. Battery capacity tends to diminish over the battery's service life. This is not easily measurable without putting the battery on a known resistance load to see how much current can be delivered over a given period of time.

 

My 12V battery discharged last week while waiting to pickup my wife from shopping. I sat in the car listening to the radio on accessory mode for about forty-five minutes, like I have done many times before, then suddenly the car would not shut off or start and the warning lights were flashing. I finally got the car to shut off and let it sit for about fifteen minutes. Luckily, during that time the battery charge came up enough to start the car and drive home. On the drive home the hybrid display had bright white vertical lines and the speedometer read way higher than my actual speed, like 70 mph when I was doing 30 mph, and the car seemed underpowered, all this during a snow storm. I disconnected and charged the battery when I got home, reconnected it and everything worked again. However, given that the OEM battery was four and a half years old and I had discharged it, I replaced it with the Optima Yellow Top S46B24R from Advance Auto. Cost with a 15% discount (Code DE31) and 6% sales tax was $198.21, less a $25.00 discount coupon on a future $50.00 purchase, which resulted in a net cost of $173.21. Below is a link to the Advance Auto deal:



Automotive Batteries & Battery Parts: Visit Advance Auto Parts for deals




Lessons learned:

1. Doesn't take much of a load to discharge a 4+ year old OEM battery.

2. Replacing the OEM battery after four years is probably a good idea to prevent being stranded.

 

A reasonable idea to replace the battery now.

Did you measure the voltage of the new Optima battery before installing it? Some other members have reported abnormally low voltage readings from a new battery. I suggest you measure the voltage after the battery has rested overnight, and if lower than 12.9V, charge it fully now.

Is it possible that you had selected the km/hour setting of the speedometer, instead of miles/hour?

 

^^^The new Optima Battery read 12.6V off the shelf. I charged it to 12.9V, which I always do to a new battery before I install it.

I had to call three stores before I found a fresh battery. The oldest battery I found was dated 09/2012. The battery I purchased was dated 11/2013. Always better to get as fresh a battery as possible, no more than six months old.

I didn't notice, but the speedometer could have been reading km/hour by default. Even so, it was still way faster than I was actually traveling.

 

Interesting to hear that a battery two months old was already reading just 12.6V. I would have expected better.

More interesting to hear that a battery 16 months old was being offered for sale. Further evidence of poor inventory management practices resulting in low customer perceptions of product quality.

 

congrats!

 

In my '13, it won't even let you play the radio with the car off for longer than about 15 minutes. A warning comes on telling you it is shutting down in order to save the battery.

 

When measuring voltage be sure to turn off all the dome lights. I don't think it's an accurate reading if they are on.

 

completely.

 

Yes. Part of the vehicle security system.

 

Yeah. It flashes so quickly it's hard to even tell what shape it is.
This is a very responsive forum that, in general provides quality information. Some people have even queried it in real time (I'm stuck by the road side - help!) and gotten helpful information. I don't think it's formally moderated, but it does appear that trolls are rooted out, otherwise the whole thing would have disintegrated in short order.

 

If the 12V battery was so drained, your car would not have become READY.

Don't get too excited about the "security system". All this means is that the Prius has an immobilizer ECU which recognizes your fob and allows the car to start.

No controls for the system are needed, just lock and unlock the car as you desire, and the security system will follow along.