My plug in battery when from 9.5 miles to 13 miles fully charged?!!!

Wasn't the the spark plugs.

What happened when you swapped out the 12V battery is you reset what the computer had been storing for the last 163K miles. It didn't have real plug-in data, so it did the next best thing, guessed from the way the previous driver drove the car and adjusted the range the previous driver may gotten when they drove the car if they used the battery. Your one year of usage merely dented what the previous driver had accumulated. Now you have a new set of data with just you driving. You have practically a brand new battery.

 

When I changed my battery I also got a new reading of 12 miles when fully charged. Since then the high reading has been slowly going down to the 7.5 miles I had previously. Hopefully your high reading stays high but in actuality, the battery is what it is and eventually the high reading will reflect that.

 

that's the factory default setting that all pips came with. it loses all memory when you disconnect the 12v, so you'll be adding new history as you charge and drive.
keep in mind, the battery icon indicated miles are not what you can actually drive. just a calculation of past dring based on the amount of charge in the battery.

 

Now im tempted to reset my pip by disconnecting the battery

 

It'll just go down to the previous figures within a week or two.

 

I usually get 9.5 miles from a full-charge. After resetting the PIP by disconnecting the battery, it went up to 14.5 miles full charge. But it gradually went down to 11.9 miles and it stayed there ever since

 

mine did something new this year. it usually peaks in the nice spring weather when i'm not using any hvac. but this year, through a very hot and humid summer, it peaked a couple weeks ago at 14.3, and has slowly dropped to 13.9 since then,

 

The estimated range is simply that: an estimate. It can be off by a LOT. What matters is how far you can actually go in EV and the estimate won't have any impact on the actual range. That's why it's called a Guess-O-Meter (GOM).

 

mine is almost spot on, because all my driving is the same or similar