mpg average stuck at 41.x after new 12V battery

I thought I read that since it was an average that you had to drive for some time (days, months?) to get it back on track. So let me know if you think it will eventually correct, or if I should maybe pull the 12v power again to reset it.

So if I fill up with gas it resets to 0.0, but goes directly to 41.x-something. Then I can watch it go from 41.5, down to 41.2, or if I try to maximize mpg it ticks up only a little to 41.6.

Before the new OEM 12v battery I was getting a much broader normal range, and could get up above 50 mpg if I tried or below 40 if I gassed it.

 

So my 2008 will reset both the mileage and the average at a fill up (I am not talking about the instantaneous reading under the "power flow" graphic).

My point about it defaulting to 41.x is not that my mpg is "less" or impacted in anyway, nothing has changed on the car except preemptively changing the 12V battery which was still working fine, the point is that it is not accurate and is displaying gibberish and doesn't change more than a few tenths no matter how I drive.

I will test the actual milegae with the odometer and report back what I get, but to be clear I am not experiencing "low mpg" per se, the MFC average mpg is just acting strangely and not updating with accurate info.

Your linked post is interesting, seems relevant, I am not sure about your description of a high/low HV battery, but I can tell when the engine is accelerating on ICE only and the display shows 2 bars on the HV battery and it typically happens at a stop/light when AC is on and using power. The ICE doesn't seem to really charge the HV much, but the regen brakes do make the bars move up. Once it has semi-full bars it dirves normally with EV+ICE acceleration and I can have AC on without "losing" bars on the HV battery.

I am regretting replacing the battery without using a 12V source top preseve settings.

Do I pull power agian and try to get it to re-calibrate?

 

Thank you both, I will look again, but I know I see 0.0 on the screen after a fillup. If my memory is correct it wouldn't creep up from 1, 2, 3, it does go back to something higher like 36mpg. Then I would see the mpg range fluctuate normally, I could hypermile and it would get up above 40, then get on freeway and get above 50. But now it just sticks at 41.x no matter how I drive, like it still fluctuates but in a much smaller range in the decimals. I will report back on next fill up.

 

Just to update after a few tanks of gas, I did notice that the MPG stayed stuck in the 41.x only fluctuating by a few tenths. I checked actual mileage from gallons used vs odometer and I was closer to 50 MPG average. Then recently the display broke out of 41 MPG on a long freeway drive and I was in 42, then 43, and now 44.2 MPG, so it seems like the average displayed MPG is slowly building up again, even though I get higher MPG real world.

This started when I pulled the 12V battery and wiped out the stored average, and before I was consistently getting above 50 on the display after all of my tuning and hypermiling. So I guess I will just leave it and see if it eventually builds up and matches the real world MPG of closer to 50. Also I can confirm that I was wrong and the MPG doesn't clear after fill up, only the odometer.