Within the last 6 months, I have replaced my alternator and all the gearing systems, all of my spark plugs, and my radiator/cooling system, yet something is still draining the battery. Every month or so the battery dies and takes 5-10 minutes to successfully jump start the car (no lights come on at all). However, I hooked it up to a battery charger and charged it to a full charge then ran my car and measured all the voltage differences from different areas which all seemed to be correct. I am wondering if there is another place that I am not thinking of that could be draining the battery. Last night I had it parked for 45 minutes to come back to a completely dead car, but it started on the first try this morning right away and ran great.
My car has 230000 miles.
My car has a manual transmission.
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It is possible to have a bad ground or short somewhere. Check the connection at the negative battery cable to the engine/chassis. Remove, clean, and reinstall it. Also check for loose connections/ground at the fuse box.
I owned a Jetta of the same generation - 85-92. A common source of trouble is the fuse box under the drivers side dash getting wet. A common source of water intrusion is around the windshield seal as well as a clogged cowl drain under hood. It can fill with water and come through the firewall through the speedometer cable and other things running through the firewall.
If you need some help with getting this fixed, consider YourMechanic, as one of our mobile technicians can come to your home and diagnose the draining battery firsthand for an accurate repair.
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