That 12V Battery...

60W is nothing. The problem is when the battery has a shorted cell and is drawing lots of current, heating up the battery case.

 

No battery temp sensor like in Gen 3?

 

Next time you encounter the non working sks, walk over to another door and try if it'll work. SKS not working usually is a result of a bad battery in your keyfob and/or you may have a stuck button draining the battery.

As for the battery meter being more stable, this is a mystery as there is no real relation to the new 12v and the HV battery connection.

 

Not for the 12V battery.

 

Happy for the OP....

It seems to of died down some.
But for many years it seemed like whatever the problem a poster came to Prius Chat with, the automatic and early reply was to " Check Your 12 Volt Battery ".
It became almost funny, as I swear someone could say their mother broke her ankle, and the reply would be " Check Your 12 Volt Battery ".

But all kidding aside....it became cliche...because it's often true. Check your 12 volt battery.
It is often a good idea and the right idea with the Prius. Because as the OP discovered, a dying 12 volt can lead to an active Gremlins amount of symptoms.

 

It is the Prius equivalent of "Are you sure the power cord is plugged in ? Please LOOK to be sure."

 

A bad battery can be worse than no battery. Once you get the car started, the traction battery can power all the electronics in the car. So, if you disconnect the 12v battery AFTER the car has started, it will work fine.

It is my understanding that the 12v battery can be as low as 9v and still start the car. At 9v a lot of your electronics will not be happy. Here is where a bad 12v battery can be worse than no battery. The bad 12v battery starts the car, and the traction battery supplies as much 12v as it can. If you have a really bad 12v battery, it can sink a lot of that current, and bring down the voltage that all the electronics sees (let's say 10 volts). That is worse than having no 12v battery connected.

With a bad 12v, the SKS could be flaky at the low battery voltage. Once the car starts, SKS is out of the picture. The ICE cycling a lot could be the Prius trying to charge up the 12v, and failing miserably. Ditto on bad gas mileage as the car is converting a lot of gas to electricity that disappears into the bad battery. I don't see why it would have an affect on the charging speed of the HV battery.

 

I know this is old, but my recent experience seems fitting enough that I'll reply.

A bad 12v battery can perhaps be worse than no battery in another way, if it is true that (as some folks have said) a Prius can be put into Ready mode with just a battery charger hooked up. On my 2005 Gen2, I recently was unable to get into Ready. I knew my 12v was old, but thought the 12v just needed charging. I hooked up a 4A Schumacher "smart" charger, but was never able to start it with that while the old 12v was in place. No luck with a jump from a neighbor, either. And no brake lights, no nothin' on the dash or ... whatever the fancy center-mount display is called. (So much darn lingo with these cars...) BUT all was fine after I replaced the 12v battery.

What I really wish I had tried, and may try still, is getting into Ready with the battery (good or bad) disconnected and a charger hooked up to the jump terminals (in a Gen 2 like mine, that's the other end of the car).

-Sean

 

Most "smart" chargers will not function if the battery voltage is too low. Also, a Gen2 needs "12V" at 25 to 30 amps in order to get to Ready and turn on the dc-dc converter and produce power.

Posted via the PriusChat mobile app.

 

This a pretty good clue that the 12V battery has seen its best days.

Just buy a new one and change it already. I am continually amazed at how people like to torture themselves.