Electrical Drain Mystery
Posted: Mon Mar 25, 2019 5:02 pm
Hello all,
Thanks for all the help with my Jetta over the years, it's still my daily driver and running (mostly) great.
I have had an ongoing mystery for several years now that i'm trying once again to solve. I thought i'd throw it to you all to see if fresh eyes gave any new clues.
Here goes, i'll try keep it brief as i can:
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Something is amiss in my battery charging system in my 89 Jetta, 1.6 NA diesel (250k).
It started about 4 years ago when i was on a long drive, and realize my battery was completely dead (my radio started to drop out, i pulled over and couldn't restart, battery was drained almost entirely.)
I got a jump, had the alternator checked (good), had the battery recharged and kept an eye on it. I had to recharge the battery because it had drained so low that even with a jump and an hours drive it was still too low to start the car again.
Over the next year or so this kept happening. Not all the time, but everytime it happened it was on a long drive. I would notice the radio go out, or the headlights start to dim, and the battery would be drained.
In trying to solve this i replaced the starter, the voltage regulator, then the whole alternator, got a new battery, checked all wire connections, belt tensions, nothing changed it.
I hooked up a digital volt-meter to the battery, and found that when i initially started the car, it was only reading about 13.9v, and the battery light in the dash stayed red. With some throttle, the charge would get up to about 14.10, and the dash light would go off. But when i add more throttle, say highway speed rpms, the charge actually goes back down to 14.2 or 14.5ish. When i release the throttle it goes back up to 14.10ish. My electrical knowledge is low (obviously), but this seems counterintuitive. I took it to couple mechanics (including respected vw diesel specialists) and they couldn't figure it out.
So then i hooked up a bypass directly from the battery + terminal to the alternator post (see yellow wire in attached pic). The charge jumped up to 14.22ish, and stayed put even with throttle.
So me being me, rather than dig deeper, i just ran that bypass through to the dash, put a switch on it, and whenever i go for a long drive i flip it on and have had no issues since. That was 3 years ago.
So now, over and above just wanting to figure out what is going on in there, i'm getting sick of all the times i forget to turn the switch off and come back to my car and find the battery completely drained because it was hooked up to the alternator all night...
-------
This ring a bell for anyone? I've read some threads on this forum that have mentioned something like a switch or relay in the steering column and could potential be the weak link in a charging system?
And if not - any ideas for how i could DIY my bypass system so that it automatically turns on and off with the car? I tried attaching the alternator post to the fuel solenoid thinking i was clever, but then of course the car just didn't turn off...
Thanks for reading this far, sorry for the novel
Thanks for all the help with my Jetta over the years, it's still my daily driver and running (mostly) great.
I have had an ongoing mystery for several years now that i'm trying once again to solve. I thought i'd throw it to you all to see if fresh eyes gave any new clues.
Here goes, i'll try keep it brief as i can:
--------
Something is amiss in my battery charging system in my 89 Jetta, 1.6 NA diesel (250k).
It started about 4 years ago when i was on a long drive, and realize my battery was completely dead (my radio started to drop out, i pulled over and couldn't restart, battery was drained almost entirely.)
I got a jump, had the alternator checked (good), had the battery recharged and kept an eye on it. I had to recharge the battery because it had drained so low that even with a jump and an hours drive it was still too low to start the car again.
Over the next year or so this kept happening. Not all the time, but everytime it happened it was on a long drive. I would notice the radio go out, or the headlights start to dim, and the battery would be drained.
In trying to solve this i replaced the starter, the voltage regulator, then the whole alternator, got a new battery, checked all wire connections, belt tensions, nothing changed it.
I hooked up a digital volt-meter to the battery, and found that when i initially started the car, it was only reading about 13.9v, and the battery light in the dash stayed red. With some throttle, the charge would get up to about 14.10, and the dash light would go off. But when i add more throttle, say highway speed rpms, the charge actually goes back down to 14.2 or 14.5ish. When i release the throttle it goes back up to 14.10ish. My electrical knowledge is low (obviously), but this seems counterintuitive. I took it to couple mechanics (including respected vw diesel specialists) and they couldn't figure it out.
So then i hooked up a bypass directly from the battery + terminal to the alternator post (see yellow wire in attached pic). The charge jumped up to 14.22ish, and stayed put even with throttle.
So me being me, rather than dig deeper, i just ran that bypass through to the dash, put a switch on it, and whenever i go for a long drive i flip it on and have had no issues since. That was 3 years ago.
So now, over and above just wanting to figure out what is going on in there, i'm getting sick of all the times i forget to turn the switch off and come back to my car and find the battery completely drained because it was hooked up to the alternator all night...
-------
This ring a bell for anyone? I've read some threads on this forum that have mentioned something like a switch or relay in the steering column and could potential be the weak link in a charging system?
And if not - any ideas for how i could DIY my bypass system so that it automatically turns on and off with the car? I tried attaching the alternator post to the fuel solenoid thinking i was clever, but then of course the car just didn't turn off...
Thanks for reading this far, sorry for the novel