Thanks Jonathan. It's not so much what's in the car as what should be connected to the bms as all I have is a switch in a box an no clues at all. I've tried the how to section on here, and google searches, but they all seem to mention disconnecting two brown wires from the battery +vet connect them together to the bms with new lead, the only brown one I can find is on the starter solenoid with the main +be from the battery so it may as well stay put. It's an may 2012 7SV 1.6 sigma 125jp tweaked by caterham to 140 hp it's just the big standard dash I didn't ask for anything so whatever it came with, I've got the standard wiring diagram from the caterham build, that shows battery master switch as just a small circle with its label and WP187 and 40 next to it, with only one wire with 250 on it. im happy to take the main +ve off the battery and connect to one side of the bms and the new lead from bms to battery. I think the resister goes terminal 1 on bms to chassis. But I'm not sure what if anything needs connecting, I think the two white leads need to come off the ignition switch to on every of the bms terminals but not 100% sure which one, nor I'm 100% sure that's it. I just don't want to risk blowing the alternator etc...shame caterham backup is useless selling stuff with no diagrams etc. Yes I'm chasing them but no info so far just want to get the car modified.