I think I'm glad it's Monday

[cjsmith]

This weekend was the first "free time" I've had since about mid-February. "Free" means only that I didn't have a scheduled commitment, not that I had nothing that needed doing. As you might imagine, after a schedule mess like that, I had lots that needed doing.

Got a lot done, too. Dumped a few months' worth of junk mail in the Sunnyvale-approved way. Ran out of paper bags. Filed bills and mail and other paperwork back as far as Christmas. Pulled ancient stuff out of the too-full file drawers (that took the better part of both days). Actually acquired a racquetball to roll the bottoms of my feet upon.* Saw the Radio Shack nearby and acquired a 15v meter I can hook up to my car's electrical system.** Plus the ordinary stuff like dishes and a grocery run. Even visited two little geocaches!

Sadly, I did not do any baking, and I'd really been hoping for that. Baking soothes my soul. It's about the only thing left that does that, since I can't run. Maybe I can bake next weekend. I simply ran out of time. It was worth it to get that filing done, though.

I think I'm glad to have the chance to relax into a normal work pace. Don't ya love those weekends after which you could really, really use a weekend? :-)

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* Why physical therapists assume that a patient who can barely walk has tennis balls and racquetballs in the house is beyond me. The least they could do for a foot problem is depend on hang gliding equipment or swimsuits!

** I want to know what condition is occurring when the battery light comes on. I'm sure some car person will tell me how little sense this makes. Some days I think that sort of thing is what my journal is here for. Heck, I'm not sure how much sense it makes to buy a meter, since I could look up the battery light in the full electrical diagram of the car for free. Maybe this is my techno-snobbishness coming out: I always prefer a meter to an "idiot light".

Comments

[wcg.livejournal.com]

In most cars, the battery light acts as a buffered ammeter. If the system remains in a discharge state for more than x seconds, where x is a parameter determined by the factory, the light comes on. Some few manufacturers (no current ones I can think of) have used the light as a primitive voltmeter, turning it on when voltage drops below some threshold value, typically 11 volts in a 12 volt system.

If the light is coming on, it more than likely means that something is causing the system to go into discharge. The usual culprit is the alternator, and the failure mechanisms are either the voltage regulator (usually internal to the alternator these days) or the brushes which contact against the rotating armature. Your garage can perform something called a "full field test" to determine whether the problem is in the alternator itself, or in the regulator.

[cjsmith.livejournal.com]

Mine flickers on and off sometimes, so it's clearly not "discharge for more than x seconds" in this case.

It helps that I already know what the answer will be. I am just geeky enough to want to see why.

[wcg.livejournal.com]

The flickering is still possible, since the way that the "x seconds" is determined is via a length of resistive wire, it heats up once the car is running, and just keeps the light from flickering while the car is recovering from being started.

So your car eats alternators? Or just regulators? Solid state regulators most often fail due to heat. If your alternator is mounted somewhere that is subject to high heat, that's probably why. Heat will also kill solid state rectifiers, which are also inside alternators. Unfortunately, it's very, very hard to reposition an alternator.

[cjsmith.livejournal.com]

Oh, so it's not about seconds at all, then, it's about heat? That I find believable. Interestingly, once the car's been running a while, the light is much less likely to be on. So it's not (say) erroneously reporting engine heat.

Obviously I need to look at the electrical diagram itself. It's not like I don't own a copy. This guesswork is mostly pointless (but fun) until I've done that.

Last couple times it's been the regulators. O'course I wind up with a whole new alternator anyway. This time, though, I can't change the percentage of time the light is by shedding/adding load. Last few times, I could. Maybe it's not sick enough yet. These symptoms have in the past been progressive.

[wcg.livejournal.com]

The voltage regulator is an integrated circuit with a heat-sink attached to it. It's got some diodes, and a little field strength maintenance circuit that basically keeps track of a reference voltage signal and adds more current output as the reference voltage drops, thus keeping the amount of current in the system matched to demand. Back in the Good Old Days (tm) it was a printed circuit with a little variable capacitor circuit inside it that was mounted up on the firewall to keep it away from engine heat, and it would usually fail when one of the relays it it had clicked on or off too many times. (Now the diodes play solid state relay.)

[ambar.livejournal.com]

Don't ya love those weekends after which you could really, really use a weekend? :-)

I've had three in a row. It's making me cranky.

[cjsmith.livejournal.com]

Yeah, "no down time" makes me cranky too. Hope you can improve that ratio soon!

[runeshower.livejournal.com]

Congrats on getting so much done! I'll be attempting some of the same tasks soon (file cabinet is too full to file anything new).

[cjsmith.livejournal.com]

Yeah, I didn't really realize how bad it was until I attacked it in one big chunk like this. One paper or one envelope I probably would have just shoved in there, but I had enough papers to file that I looked at the drawer(s) and said UH OH.

G'luck with it. Mind numbing, but I'm glad it's done!