brake, vsc and and lights on!

The battery likely has a shorted cell and I would not advise to drive the vehicle any distance.

I am surprised you can get into ready mode with the voltage that low, and the fact that both the power steering and brake power assistance both require a good 12 volt supply you could be putting your life and the life of others in danger.

The car will loose trouble codes with a bad 12 volt battery, but the car will also generate all sorts of odd symptoms and messages.

If you have a jump pack this could be pressed into service as your battery but if you do this I would advise disconnecting the OEM battery as this could discharge your jumper battery pack.

John (Bitprius).

 

Obviously I cannot without testing be certain that you have one or more shorted cells in your battery. But the fact that you were driving the car at the time the lights came on "so the battery was being charged" strongly suggests this with a battery voltage of only 9.7 V immediately after driving.

As a retired electrical engineer I cannot in all conscience in any way say that your car is completely safe to drive or will not let you down. I am not trying to scare you I am just being realistic.

You may also have other problems, but the most likely thing is all this is caused by the 12 volt battery and once replaced things will be back to normal.

A low battery stops the ECU's storing the fault codes, that is why many posts on here suggest disconnecting the battery to clear the codes a low battery does the same thing. No doubt someone else will post confirming what I have said.

Hope this all makes sence.

John (Britprius).

 

Just one quick question is this the original battery on the car.

John (Britprius).

 

If you want to try to save yourself some money, take a little time and get a replacement 12 volt battery and swap the new one with the old one. If you are somewhat mechanically inclined you should find the job is simple and straight forward. I just changed ours, it took me 1.5 hours to do it on my own. I used two wrenches - both of which were 10MM and 12MM, two 3/8" drive sockets - both of which were 10MM and 12MM, a few extensions along with a ratchet (3/8" drive), a flat blade screwdriver, and a small hammer.

If you do change the battery, make sure you disconnect the negative side first and then reconnect it last. It is pretty obvious that your battery is bad since it is a LOT less than 12.6 volts (100% charge) and that it is six years old.

Good luck to you.

Ron

 

Glad you got it sorted for not to much money. As you can guess I had a very strong feeling from the voltage from the battery directly after use that a cell had shorted.

John (Britprius).

 

$240 is a good price for battery with install. Average price for the battery alone is $200 plus, so you got off pretty good imo. Glad to hear you got your problem solved.

Good luck to you.

Ron

 

Try going to one of the auto parts stores or shops that will read codes for free & let us know what they find.

 

Makes sense so far, then you wrote:

Sorry, but I am confused. You mentioned rt rear wheel sensor in post #8 this string, and then you again mention a rear wheel sensor in post #11. Did you decline the sensor when you had the battery put in, or have they replaced one and now they think another sensor is bad? If you can get the DTC codes and post them, it might help to clarify things.

I know the feeling about repair cost's on car's. Everytime I do work on ours, I think along the lines of getting something newer. Then I stop and think some more. I end up saying "This one is paid for, I don't want to start making payments again."

Hopefully lady luck will shine on you soon.

Ron

 

The to me bad side of the OP's problems was that the dealer told the OP that it was ok to drive the car on a 150 mile journey with the battery in that condition. This shows a complete lack of understanding of how the Prius works.

With a shorted cell the other cells would be in permanent over charged state making it likely that another cell would go down this could have given rise to a dangerous shutdown possibly without power steering and power assistance to the brakes, as both systems work on 12 volts.

John (Britprius).

 

The wheel sensor will not affect the steering it is the 12 v battery that I was concerned about as that affects just about everything on the car. Glad it was not your own dealer that said just drive it.