I've just changed the battery on my blob spec-c, I opted for a slightly larger one (+3kg might as well be a lardy UK STi one now)... however it's completely changed the car.

The stereo is a lot louder, the lights seem brighter which would make sense if the old battery was knackered.

BUT...

The car now drives very differently, before you'd get full boost at 3.5k 1.6 bar and now you don't get it till just over 4k and it's only 1.5 bar. However before the car used to drag down over 7k and now it almost surges forward at 5k and pulls with full boost all the way to 8k with ease.

The car was mapped 350 /350, is it possible that when I've changed the battery over that it's lost the map? It's a standard ECU that's been mapped. Although it's got less boost pressure, the car is now faster, well feels faster at least. Also, would the AVCS work if the voltage was too low?

I'm sure it's a positive change, but I'm not sure exactly what's happened!

 

I thought the terminals were smaller on the spec C's so bigger battery wouldn't go on

 

It does have the small terminals, mine's an RA which has an extra small battery, I've technically changed up to a standard Spec-C size...

 

changing the battery wouldn't change the map, the map file is written to the ECU's memory where the original map file was so there's no way to lose it. What has likely happened is the ECU has reset though so you'll have a little bit of driving before it returns to it's usual self.

 

I'm going to try and get some miles down it and see what happens, it runs great, if not better than before.

Thanks for your replies.