Sorry to hear you're having so much trouble, Bob.
I'm still playing with the alternator? regulator? battery? problem in my
'83 300D because I want to figure out "why" I, and many other people, are
having fairly frequent problems.
I've set up a bench test with a new shop battery (that's normally a backup
for the burglar/fire alarm system) so I can test alternators and
regulators. I still need to find out the size and type of charging light
bulb, the 18 ohm resistor, and the diode in series with it; all of which
are in the instrument cluster; in order to duplicate the charging system
on the car. This part of the charging system is not intuitive, (See
schematic from the shop manual sent separately), at least to me.
One test that seems to be missing from the current FLAPS DIY protocol is
specific gravity, and hence the state of charge, of the battery. It's
messy and it's easy to get burned with battery acid, so FLAPS; Autozone
and Advance at least; don't test specific gravity and will argue with you
if you tell them the sp.gr. is off in one or more battery cells even
though their handheld testers show that the battery is good.
Instructions that come with new Bosch alternators say that battery must be
fully charged before installation or the diodes can be damaged. Under the
current methodology no one knows the state of their batteries charge
because they don't test it's sp.gr. Could this be the reason some on the
list have frequent regulator and/or alternator failures; they are throwing
a heavy charging load on the new parts as soon as they're installed?
Gary said that Bosch products are not what they used to be, so treating
them gently may be especially necessary.
From now on my first test will be specific gravity done with a real glass
hydrometer (not the cheap plastic kind). If the readings in all the cells
are close; no matter what the sp.gr./state of charge, the battery is
probably okay. That's the way we did it with the old type batteries.
The next step will be to charge the battery with my 10 amp. battery
charger set on MANUAL; (automatic settings are useless on my charger); the
cell covers off, and a disposable rag lying over the open cells in case
the bubbling electrolyte splatters small amounts onto the top of the
battery.
After charging for an hour, I'll let the battery cool down and then
re-check the cells sp.gr.
in order to get an idea of how fast the battery is charging. I don't want
to overcharge and damage the battery.
If the sp.gr. reading are approximately the same in all cells after the
battery is fully charged, I'll assume the battery is good and then install
the new alternator and/or regulator; or test the charging voltage on
those that are already installed.
If a cell is down in the "red" range on the hydrometer and the other cells
are in the green, I'll go back to the battery seller and demand a new
battery after showing him/her the sp.gr. readings on the current battery.
If the battery is good and the charging voltage is low, I'll replace the
regulator and check the charging voltage again. If the charging voltage
is still low, I'll replace the ALTERNATOR (CORRECTION).
Good luck with solving your problems, Bob.
Gerry
.............................
From: Bob Rentfro <azbob...@gmail.com>
This thing wouldn't start today.... in the rain.... after I had been in
the dentist chair for 90 minutes. AAA jumped me, drove straight to
O'Reilly's to get a quick and dirty alternator check. Voltage check with
engine running, 11.0 volts. So....which is more that likely the culprit...
alternator or voltage regulator (which I replaced 6 months ago)?.
Bob R
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