depends on battery make a lucas LC038 , Bosch S4 001 Car Battery 12v 44Ah 440A (063, 544 402 044,
Halfords HB038 Lead Acid 12V Car Battery 3 Year Guarantee 953034
just make sure the + and - terminals are correct way around as some batteries have the terminals other way around ( when battery is facing you and the terminals are closest to you the + terminal should be on the left hand side )
its quit sensitive so i think there must be some sort of feed back signal from the throttle position sensor as the butterfly does not open much at all and with out something like the ark 4 the idle is all over the place and it revs quit high if you adjust screw on its own and once its out of adjustment you need some diagnostic kit to reset it to where it should be i known the ark 4 will do it but there hard to find so defiantly nice if could be done with a pscan diagnostic tool
on ark 4 when you have the engine hot enough it will give you a display with a range of steps for the stepper motor to be in you adjust the throttle butterfly screw to set the required rpm then when you exit out from the menu it asks to save the new settings to memory with out the ark 4 you can not save settings so must be some sort of code being sent to ecu to keep the new setting