Car question

[glatt]

And this is the voltage. In other trips, the voltage remains steady at around 14 volts, but on this trip, it was fluctuating. You would expect it to drop a lot when the RPMs went down to 200 or so, but it was dropping even before then.

[glatt]

Just for comparison's sake, this was a trip in the car the previous day, and the voltage then.



So what could cause intermittent voltage changes? If the alternator intermittently craps out, what's causing that? I don't hear any belts slipping and squealing, so I doubt it's that.

[tw]

Originally Posted by glatt

And this is the voltage. In other trips, the voltage remains steady at around 14 volts, but on this trip, it was fluctuating.

Voltage in that last attachment (18 Feb) is ideal voltage for all vehicle electronics. Ideal voltage is typically anything from 12.6 to 14. Apparently voltage is a little higher (maybe 14.5) on 18 Feb implying the battery required more recharging current. Which is the alternator working just fine.

On 19 Feb, the first thing that concerns me is the idle dropping to less than 750 RPM. That should not happen. At 750 RPM and lower, the alternator really does not output much current. In fact an alternator often outputs near zero current if RPMs are well less than 800. (BTW, maximum output current starts at maybe 1500 RPMs which means racing an engine any faster does not recharge a battery any faster).

A sudden marked voltage drop on 19 Feb could be a drop much lower than the graph indicates. But that typically would not cause problems as long as voltage remains above 9 volts. Battery (without alternator) should provide enough power. However, is there any reason why neither alternator nor battery maintains above 9 volts? One possible reason is an intermittent ignition key switch. Or an intermittent relay that should but does not hold battery connected.

500 RPMs is a defect. During those 500 RPM periods, was the engine not surging or stumbling? Fact that the engine idled at 500 RPMs is itself an engine defect even if the engine did not stumble. A perfect example of viewing a 100% defect even though the engine appears to be working just fine (not stumbling).

So an interesting question. Is low voltage somehow causing the engine to idle below 800? Or is idle below 800 causes a significantly lower voltage? An example of trying to solve a closed loop system.

[glatt]

I had ordered an LED light array meant to go in your car's trunk instead of the little wimpy incandescent light bulb that came with the car originally. It uses less electricity than the old incandescent and is much much brighter. Pretty cool, actually. Only $4 on Ebay.



Installation was easy. You just take out the old light bulb (quickly before it has a chance to heat up and burn your fingers.)



And then put the appropriately shaped light bulb adapter into the socket. Connect the light array, peel off the adhesive backing and stick it to the underside of the trunk. The light output is pretty impressive.



So bright, and uses less power.

But I was too smart for my own good. Apparently the Camry has a circuit board in the back that checks the resistance of the light bulb circuits, and if they go outside certain parameters, it turns on a warning light in your dashboard that your tail light is out. The resistance is so low on these LEDs that the circuit board thinks there is a problem. I'm getting a warning light on the dashboard.

[Gravdigr]

Originally Posted by glatt

...I'm getting a warning light on the dashboard.

[xoxoxoBruce]

With the trunk closed, and the light off, the Camry is concerned the bulb may be bad? WTF?

[glatt]

I think it has a memory. I popped the trunk with the engine running the other day, and the light came on shortly after.

I dunno. I checked all the tail lights and blinkers and reverse lights and they all work. And this warning light came on shortly after I installed the LEDs, so I think that has to be it.