Hi wonder if anyone can help… I needed a new battery that was fitted to my car today, before fitting the battery as I was low on petrol it flashed up distance to empty was 22 miles, after fitting the new battery when the car started it said distance to empty was 50 miles. So it’s jumped up to 50 and counted back from that on my journey home. 
I know you have to reset the bms so that your stop start works but that hasn’t been done yet. 
has anyone got any ideas why it would do this? I don’t want it to always tell me I have 25+ extra miles of petrol than I actually do.

any help would be appreciated.

I stand to be corrected on this but I think your car measures recent fuel usage/driving style but as you've now interrupted the power supply by changing the battery, it may have defaulted to an average setting ?? I suspect that once you re-set the BMS and have driven for a few miles that normality will be resumed ??

Why haven't you re-set the BMS though as it's a 30 second job ??

1) Ignition on

2) Sidelights on

3) Press rear fog light switch 5 times

4) Press hazard light switch 3 times 

5) Wait for battery light to blink twice. 

 

Simples !!

Oh is that all it is? I will try that. I thought I needed something to actually reset the bms

Hopefully you;ve got a way forward now due to the helpful replies above.... but playing devil's advocate - how do you know which is correct - the 22 or the 50??? Maybe it was wrong before and is now correct?????

No one seems to know how it works.  It needs to estimate how much fuel left in tank and how many mpg it will do.  How can it know how much mpg you will do with the fuel left? It cant know.  So it has to use a guess based on what mpg you have done before.  But what is ‘before’ is it the last 5 miles, or 10 or 50? Or is it the last complete journey, or is it the last one hour of driving?  No one seems to know.