well it's been an eventful day.
this morning set off at 8am to andys for modified live show at cadwell.
at 10am as I was on m62 passing m18 I noticed the wideband gauge was beginning to irratically restart, showing "E9" error which usually only shows when ignition power was reapplied, then goes through heatup percentage values, hmm odd.
it began to occur more frequently & randomly. eh thinking could there be a loose ground? sensor going bad? although it's relatively new and previously when it goes bad it shows E8 heater error rather than E9 power error, so continued on..
then it got so frequent till it just stays flashing at E9, wtf? is the sensor dead? it still runs and nothing I can do to it.
moments later, my cd mp3 stereo began to restart itself in the same pattern as the wideband. selected FM radio that requires less power and it's stays on fine, then resume cd player and it restarts itself again till eventually it all dies. oh crap I have a big electrical problem.
then the temp gauge was reading lower than usual. then the tacho shuts off. then I noticed the engine beginning to cut off under high load (similar to when my boost pipes & MAF pops off the TB and loses all power)
oh crap, the hard shoulder was full of cones, had to nurse her long as I can to reach empty hard shoulders and immediately pull over.
in neutral, engine stalls, dash lights dim, turn on hazards and is very dim and flashing faster dimmer as battery dies.
the battery is literally dead, multimeter says 9V, oh pants.
I had no battery light warning at all but I think the alternator wasn't running till the battery eventually drained.
was 1hr away from andy and wasn't gonna make it in time. checked fuses all intact, alternator wirings fine, puzzled.
if alternators duff and breakdown can get me going for abit, andy has a spare but he's living house from 11:30.
if it's more serious then I'd have to miss the show and have the guy recover me back home instead.
no option but to call for breakdown service. holly from call centre informing me they'll be bout 60-90mins.
gary in green van turned up at 11am
connected his battery booster, hazards flash more brightly, crank and she starts.
battery terminal with the booster connected says 12v.
lets check if the alternator terminals working? test the outer metal nut & threads n 0v. test the inner part of the teminal and I spotted 14v, oh could be bad connection.
took apart and the pegs have heavily oxidised. we sanded it shiny, try again and yay it outputs 14v.
unplug the booster, battery still says 12.5v n rising, so it's charging.
disconnected the battery whilst running and doesn't stall, meaning the alternator is now generating 14v to keep the system running.
all fixed, simple problem 
was able to goto cadwell with andy n family, then return home for stag do.
just have to wirebrush this alternator for good tomorrow.