Decrease in MPGs after installing Optima Yellowtop

I am new to the Prius world (4 weeks in) and have a 2005 Prius (level 4 i think, HIDs and smartkey) with roughly 110K miles. Twice in the last 4 weeks I have gotten strange messages on the 7" screen (MFD?) one said something about having the vehicle on a flat surface before placing in park and the second issue was not starting and getting the RED triangle. Both times I was able to get the car to stop and or start by playing around with the START button and/or switching key fobs.

After doing some searching on the forums I concluded that I should probably replace the OEM 12V battery. Most of what I read suggested replacing with the Optima Yellowtop battery. So I ordered the battery from ELearnAid and it arrived in 2 days from the date of order (that is to the EastCoast!)

I followed the directions provided in the box and was able to complete the battery swap in under 20 minutes. Once I had everything completed I took the car for a spin to make sure everything was working. I did not use a 12V back-up battery as I didn't think it was necessary and i have no issue with resetting the radio, one-touch window and odometer.

The issues:

1.)

I drove the car to perform several errands and noticed that the gas engine kicked-in at around 11MPH regardless of the slope of the road I was on. Before the battery swap I noticed the gas engine would kick-in around 35MPH. I also noticed I averaged around 35 MPG for roughly 18-25 miles of driving. On these same roads I think that MPG should have been in the mid 40s.

2.)

When I received the box from ElEarnAid there was no "Install Kit" in the box, just the battery and the directions for installation. (The invoice that was in the box clearly stated that the order was for a battery and an install kit) For cars with Smartkey do we not need the install kit with the new Negative and Positive wires?

Any insight would be helpful.

Thanks guys

James

 

thanks for the reply. I was able to check the voltage using the onboard diagnostic and the reading was 11.7V. Does that sound correct for a "fresh" battery? I will connect to a trickle charger and see if things improve.

I did read that sometimes the prius computer has to reboot after an electrical system change (like a new battery) and after this period things should return to normal. Is this true?