I have one from an old 83 4000 audi and I was thinking about transplanting it somehow. My battery died 3 times already in a year and I wanna know whats going on with it (stupid reasons for dying tho, dad, mom etc..)

PS there is also a "bar" meter
whats that for?

 

as for the voltmeter, hook it up to a 12 volt source to get the readings.

I'm guessing the "bar" meter is to measure turbo pressure...is the Audi a turbo??

 

i installed a voltmeter for the same reasons, faulty battery and bad alternator. you can see it on my cardomain page. I was lucky to have this voltmeter because after i installed a remanufactured alternator, the car was good as normal again, however if it weren't for the voltmeter i wouldn't have known the alternator wasn't putting out proper voltage, basically it was only giving me 12.8-13.3 voltage.