New battery, new mpgs

Congrats! Welcome back to great MPG. That $50 coupon was a great find too.

 

Just a note that not all failures of the 12 battery cause lowered MPG, but some do.

If your battery has one dead cell, the inverter will try to charge it and fail, continuously. this wastes energy and reduces MPG.

If all the cells just have reduced capacity, a new battery will make your car more reliable, but won't effect MPG.

 

Max voltage even after you charge it will be near 10 volts not near 12 volts.

 

But this can be easily measured !!! Loss of a cell reduce the voltage about 2.3V very easy to notice (OK I have SG) and regularly check with a cheap multimeter...

So if you measure it it will be btw 10.8-11.5V right after you just stopped the car ...

 

I just ordered a new battery from Advanced Auto with $50 coupon too. I'll install it this weekend and see how my 06 Prius works. I've been getting Warning lights Hybrid, VSC and Brake with no apparent problems with the car. Sometimes it goes away, and it's worse if I have Wireless Key Entry turned on.

 

It is not that the Prius is worse about 12 volt batteries than other cars, it is that we have learned to tell when a 12 volt battery is dead by the sound it make running a starter motor. Since the Prius has no 12 volt starter motor, we miss the other clues.

 

Unless one constantly monitor's the state of the 12 volt battery in the Prius, they usually find themselves with a discharged battery at the worst time. The Prius will give warnings, however they are not like a normal car as Jimbo pointed out. One way to monitor the state of charge in the Prius is with the test that Jdenenberg posted here on Prius Chat. Also, one can check the voltage with a digital volt meter. A fully charged AGM type battery that is normally found in a Prius should measure a minimum of 13.0 volts or higher. A weak battery will measure just above 12 volts and less.

The following is a good way to test the battery on the Gen II Prius

Weird stuff happening? MPGs dropping? Test The Battery | PriusChat

 

Hi all. I'm new here. I've owned a 2008 Prius since 2010. Overall, it's been great. I just started a new job that is 50 miles away. 42 of those miles are interstate. I've noticed the mileage has dropped, which I contribute mostly to cold weather, but this has happened before, just not to this degree. I'm thinking it may be the battery, as you guys have previously listed. I'll be testing the battery this weekend. How do you get the HUGE50 coupon?

 

But did not you just stated that your driving pattern has recently changed ??? Could that be a factor ?? I would not discount that ... although if the battery is the original ... it is surely close to its useful life even without any mishap..

 

Yes, my driving pattern has changed. I realize that highway driving will lower the mpg somewhat. The battery is the original. That is why I assumed it is probably time to change it.