mx5cartalk.com

This morning I jumped in the car to find a dead battery... strange as its my daily driver and I haven't noticed any warning signs. So I checked the battery using a multimeter, and it showed 10.5 volts. Strange again, I thought, that should be enough to get the interior lights going at least, but not so.

The battery in the car wasn't a sealed one, so I thought I might as well replace it anyway. Picked up the new one, connected it up, and we have interior lights, so I thought all is well. I tried to start the car, but there was just a loudish click every time I tried to crank it.

I thought it must be the alarm cutting in with the immobiliser, so I set about reading the manual to reset the alarm. Within 10 minutes, no interior lights, nothing... the new battery is drained completely...

WTF?? Any ideas?

sounds like a big short somewhere, maybe even a battery cable worn through to run it down THAT quick, the clicking you heard is the solenoid trying to engage & failing from either a) sticking or b) not enough current, given what has happened i'd say b is the culprit

btw, if your immobiliser had been doing it's job, you wouldn't have heard any clicking

Problem solved, the culprit was a dodgy connection near the battery causing an unreliable flow of juice.