I Iike that idea, even if the problem was a dead short, the bulb could only go to it’s maximum brightness.
In this case it will, the filaments own resistance will act as a current limiter. That way the battery will not drain very fast at all. perfect.
While I have used this idea when working with 110Vac on a TV before, it didn’t come to mind here.
I’ll pick up the IR thermometer tonight in case that might help, and a socket and bulb from the same person, who has all this stuff laying around his garage. I’ve got a large stock of parts, but for the electronics I design and build. No 12V incandescent bulbs.
Thanks @PvtPublic!
No snark was intended. emails do not always communicate well.
Your second email stated that you had run the car using just the power supply. This is why I was trying to clarify running vs non-running.
If there a strict timing to this problem, that would be a clue.
An old incandescent headlight would be a good 12 v lightbulb, but you would be putting it in series with your problem load. You might need to keep a voltmeter across it as you pull fuses. It might be useful to pull fuses a whole bank at a time. (UVA is using that philosophy as they look for covid in the sewers.)
I am very happy, (And am orgasmicaly relieved to say) your idea was the one that made the repair happen. The fact that I no longer have the facility’s to take my time and be my normal-thoughtful-trouble-shooting-self on anything electrical, meant that something that did not drain my fully charged battery as I worked, was the way to go. Today, as I was looking for my internal to the car fuse panel, I noticed a slight (and I mean small ) tap on the passenger seat, and it was repeating. As I had mentioned previously. the drain was cycling on and off. I immediately knew that one of the 2 seat motors was trying to do something. As the seat was in the middle of the front-back travel, and the tilt (up-down) was all the way up, it had to be the tilt motor. I reached over the side of the seat and found a wire going to the GPS unit(yeah, it was unplugged to rule it out) was wrapped around the seat tilt switch, and pinched between the tilt switch, and the seat itself, holding the switch in the raise position! I am surprised such a switch would be powered while the car is off. But I do know that most of the motors have their own method of limiting over-travel, (a bi-metalic switch that works just like the original blinker units, only it is much slower in on-off cycle.) Think about this, it would cycle, until the battery got so low, it could no longer heat the Bi-Metalic limiter enough to break the circuit, allowing the last of what was left of the battery power to continue to drain the battery to nothing.
While @oldnotdeadyet played semantics about the fact that my battery was not OEM because the car is 20 years old, YOU gave me the extra T-shooting time with your idea. Again, I’ve used that method on things other than cars, but you reminded me of that very useful technique.
Once the switch was released, I checked the current draw again, and it was a around 38mA. A bit higher than I would like to see, but maybe something in the ECU may have not timed out yet. Happily, after a drive, then a 1 hour wait, the battery was at a 12.96V float voltage! I stand by Interstate batterys, as this thing had been drained to nothing, twice.
Thanks to everyone with helpful ideas, some I had not heard before and will doubtless use later, if not on any of my own vehicles, while helping someone else with their car, which I do with regularity.
-Craig. (real name)
Glad to hear you solved the problem. The series load trick is a good thing to use on problems like this. The 38ma. current draw you measured is well within the normal current draw range while the car is parked so you should have no trouble now. I like to use about 50ma. as a general limit but I think there may be some models that use more than that for a normal draw on the battery.
Thanks @Cougar,
I was indeed looking at the higher current circuits as you had suggested, given the high amp draw. This whole thing reminded me I need a wiring diagram for my car. I usually have one for every vehicle. One of the curious neighbors managed to blow out my power supply while I was in the house, and that meant having the battery get below start-able was no longer an option, making that Current Limiting option all the better. So now I am searching for output transistors!
This is my main mode of transportation for work, so I am still a happy guy. It’s always handy to have other knowledgeable people to bounce ideas off of.
So now you have a good working car but a bad power supply. It seems there is always something that needs fixing. You might try Digi-Key or Newark Electronics for the transistors.
So glad to hear that this difficult symptom was a cheap fix. Clearly, ears are a good diagnostic tool.
As far as simultaneous problems go, I had my truck’s rear brakes all apart, and while getting tools, I find my water heater leaking. I suddenly needed the truck to pick up a new water heater? And with bad luck coming in three’s, I am very wary at the moment.
Thank you, @ oldnotdeadyet
The water heater in the house I had purchased lasted all of 4 years before it corroded through the bottom, and started leaking like yours. And it did have a well maintained water softener before it.
I’m sure like me, you will be doing that job yourself. I hope for your sake that the "in three’s’ thing turns out to be superstition, not reality.