in the 80s the current draw from a battery was only for the starter(lol)... and if the car wouldnt start i can guess what you ll do... now you can have a full diagnostic tool that you can even test the compression of your engine or see how many times the ecu woke up during night and current draw at specific time and even test its capacity... find parasitic draws etc by the way in the 80s the phone was not mobile and talking was by letter... i know because i borned one year after (P.S. did not saw the clip yet..)
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In the 1980 I installed a voltmeter in my car.
I didn't need a mobile phone or Bluetooth.
in the 80s the current draw from a battery was only for the starter(lol)... and if the car wouldnt start i can guess what you ll do... now you can have a full diagnostic tool that you can even test the compression of your engine or see how many times the ecu woke up during night and current draw at specific time and even test its capacity... find parasitic draws etc by the way in the 80s the phone was not mobile and talking was by letter... i know because i borned one year after (P.S. did not saw the clip yet..)
...or you can get a cigarette lighter type that just plugs in!