This is a sign of a bad battery. One way to test it is to charge it overnight, and check the voltage of the battery when you crank the engine...should be over 9V at the battery post. Under 9V is usually the bat. If the Bat is over 4 years old, it's probably a good idea to get a new one anyway, always check the cables before checking the battery or alternator, even a slight "gray" film can keep the system from charging. Always clean a connector everytime you take it off.
Alternators don't charge much at idle, the battery should be able to run all the lights, etc without dimming even with the car turned off.
ok, good points...the battery is not old...first owner was changing it regularly (sat in a garage for 6 years, alarm system kept killing it, which has subsequently been removed)...alternator is only about 5000 miles old...I have disconnected the battery several times while working on other areas, but thought my connections solid...I'll clean the posts, check the belt, and check the voltage as suggested.
How in tarnation do you keep up with all of these posts' locations? Anyways, thanks. I understood about 65% of it, but
then, I'm old. After cleaning/abrading the negative post, I noticed my voltage at only 10.55 V...also, that "volt meter" referred to, I believe in the glovebox, makes an unattractive "clicking " noise during failure to start the engine...the battery is probably bad...on tightening the alternator belt, how much play or displacement should I "feel" with my fingers in the belt that is acceptable...1/8"? NONE??
This will probably start a war but here is how I do it.
If the longest distance between the center of the pulleys is between 7 and 11 inches I check the belt deflection for 1/4 inch.
If the longest distance between the center of the pulleys is between 12 and 16 inches I check the belt deflection for 1/2 inch.
When adjusting the alternator belt on our L28's check that the bolt holding the adjusting bar to the block near the water pump is tight. It is difficult to get to if you have power steering. Mine was almost falling out and I initially thought the alternator was shot.
I do not understand what you mean by "also, that "volt meter" referred to, I believe in the glovebox," please elaborate.
10.55 V would lead me to believe that one cell is dead. If the battery is not sealed (maintenance free) you may find that the water level is low. Top it up with distilled water and put it on a battery charger for 24 hours. Examine the battery, if it has bulges in the case between the cells it is probably toast.
When using a battery charger hook up the cables to the battery AND THEN plug in the charger. Obviously unplug the charger before removing the cables.
I appreciate your thoughts on the belt and the tips..I assume when recharging the battery should the alternator be disconnected at the battery, or unneccessary? My reference to a volt meter behind the glove box may be a misinterpretation of a module there, misread from another post...just plain ignorance on my part. Battery has two cell covers on it...one appears to have fluid near the top, so may be about gone...daggone it I forgot to recheck the V this morning...and yes,I have a power steering pump in the way...c'est la vie.