Does anyone know how dealers check for electrical "leak" in any given car? That is, how do they check that some component in the car is turned on and consumes electricity when it's not supposed to?
I assume they measure current flow but where, at battery terminals? Could such minor current flow be detected? I've been told they do but have never thought about how it would be done.
On the newer cars the diagnostics system log fault codes should something continue to draw power after the ignition has been switched off for 15 mins or something like, on vw's diagnostics, i do vag diagnostics for a living.
Other than that you can use an amp meter connected in line with the positive or negative wires on the battery, or you can buy an amp meter which reads electrical current without touching the wires, this is ideal because you can't blow anything should something be pulling more amps than your 10amp max multimeter can take.
Then once the current measurements been taken you can start to pull fuses one by one until the leak has been found, obviously your going to get current draw with ignition off but it must be relativly low less than 1 amp, just pulling 1 amp would only last a 70 a/h battery 70 hours would last 2 hours off 3 days, so you can see for the vehicle to be parked for weeks it needs to have a low parasistic current drain.
Most vehicles have multiple wires and fuses for power supply to fusebox, ignition, starter feed, alternator return etc, so it's very easy to isolate different parts of the electrical system, and test each wire to narrow the current leak down.
There can be short circuits but theses normaly blow fuses, on saying that it depends on how much the short is pulling.
The best battery i've found is bosch, a friend of mine has a 10 year old bosch one on his old mk1 golf gti and it just about turns his engine over after sitting connected for months on end in his garage.
When my battery went i got a bosch one!
I just noticed how long i've been on here for, nearly 5 years i'm stuck in a time warp, can't believe it's been that long, 5 years later and still no porsche