I did a partial grill block of the top grills and there was no impact,
the bottom grill (intake) I tried blocking and on my drive to work as I expected the temp of engine where the gauge usually reads at the 50% (halfway point) was now at the 3/4 mark. Which I expected.
On my 16 mile jaunt to work which is mostly highway driving the Check Engine Light comes on, then the Battery indicator comes on.
I check the scangauge and the battery is like at 17.8 to 18 volts.
Now the temp gauge is no where near overheating but I forgot to check the scangauge for engine temp.
In any case, what the heck can cause the alternator to flip out like that?
Needless to say I removed the blocking on the lower part of the car and we will see what the ride home does.
I would say it's probably the Rectifier / DC regulator on your alternator. There may be components in that circuitry that don't like the higher temperature and not working properly. See if the problem goes away without the grill block.
yea im betting the regulator bit the dust. if you start it and it goes up to 18V (might have to rev the engine) i would not drive it as it can possibly explode the battery and or fry certian components (fuses might blow but thos eonly blow if over current, not voltage)
Remember, as voltage increases in a circuit, if all things are the same, the current draw goes up.
I used to run those little 3v hobby motors up to 12v and in very short bursts as high as 18v. They might only pull .2-.5 amps under load at 3v but at 6-12 it gets to about 2 and at 18 I'd had a couple pull as much as 5-7 amps, melting nylon bushings, frying brushes, and melting solder in no time. At 50 cents each I couldn't help but run like 40 of them into the ground.
As for your alternator issue, did it go away after the engine cooled? If not, your regulator took a dump but if it did then your regulator overheated.
Well, one thing which is probably going on is if you've got the grill completely blocked, which it sounds like, the water temperature went up and the electric fans kicked on to try to cool it down. On my car, when I had a grill block, I had to leave a 2 * 4 inch opening, or the temperature would start to climb. A grill block should only be done, if it can be done without causing an increase in your engine temperature. Otherwise your efforts just lead to the fans coming on and potentially overheating the engine.
It's not the rectifier circuit that's causing the issue. If it was the alternator would go out of phase and stop charging or would start outputting AC instead of DC and probably hose electrical stuff really quickly. All the rectifier is really doing is turning the 3-phase output of the alternator into DC.
The problem is the regulator getting so hot that it can't hold back voltage anymore so it spikes. Semiconductors tend to do that when they overheat.
Check your battery terminals and make sure they are not loose. Sometimes the alternator uses remote sensing on the battery voltage and if you have a bad connection the alternator will try to increase the output voltage to get the current to the battery and if it doesn't get there because of the loose connection the voltage can go way up. If the belt isn't used for anything else than the altenator you can still drive it for an hour on just battery power assuming that the battery is good by taking the alternator belt off the pulley.
Grill blocks in the summer is NOT a good idea unless you have a very high mpg car - just walk next to a line of cars in traffic on a hot day and feel the heat coming out of the cars on the road and you will understand why a grill block is not a good idea.