Alternator question and comment re 4bagger and disc brakes.

[heinz wittenbecher]

Not a funtime was had by me yesterday/today.

Blew an alternator (that was the easy part), and then th AC Compressor
bearing went... and 120 degrees in Redding, CA...

Anyways, I had to get an Alternator at a partshouse and as they didn't have
a good match and as mine are aftermarket I ended up with a 100 amp one that
looked identical and fit like a glove.

At idle the output volts were 12.9-13.4 which I considered to be quite
normal when compared to my old one. Once I hit freeway speed though it crept
up to 15.2-15.8 at which point I disconnected it and kept running on GenSet
as it was running anyways for the roof Air.

I've never seen voltages that high and suspect I have a duff one but thought
I'd ask here before yelling at the parts store the next time I go Through
Redding again.

Running on the Genset sure was a bail-out as at least I got to Stockton only
8 hours late vs days.

BTW, this was the first sizable distance trip with new four-bagger and disc
brakes all around. Excellent on both counts. All the hassle re bleeding,
etc. was definately worthwhile.

I'll update my website when I get back, but first I have to get some work
done and then I have to get back. Aside from the Alternator problem I'm
currently running without dash AC as the compressor is bypassed with a
shorter Serpentine Belt.

Thanks in advance for info re Alternator volts.

Heinz
'76 Transmode - currently 'on-the-road'.

 

[donald w. miller]

Hmmmm, almost another voyage from hell?

I took a look at the GM book since you probably don't have yours with you.

Oddly enough it says little about voltage but mentions above 15.5 as too
high with a fully charged battery. They say get out the hydrometer and
don't forget to water the batteries.

They mention checking the #2 lead with an ohm meter to make certain it is
not grounded. The insulators are sometimes left off or brush leads become
shorted to ground, etc. This lead is connected to the battery through the
fusible link and would blow it if there was a ground fault.

Another item is the higher than normal heat. As temps increase the voltage
needed to fully charge the battery decreases. The regulator has a
thermistor to compensate for temp and it may be defective.

Prevailer gel cell optimum varies from 14.5 volts at 32 F to 13.2 volts at
122 F. Flooded cells are a few tenths volt different but I forget whether
it is less or greater.

I don't think you can put the field plug in backward but if so ????????

Then there is the infamous diode isolator which may be a contributor. It
will have some voltage drop across it so the alternator voltage will be
higher by the amount of that voltage drop, than a system without one.

Many cruising boaters have replaced diode isolators with a solenoid actuated
by the engine oil pressure switch. Said to be much more reliable.

In any event the voltage sounds too high to me.

Happy Trails,

Don

- -----Original Message-----
From: Heinz Wittenbecher
Date: Sunday, August 16, 1998 03:55
Subject: GMC: Alternator question and comment re 4bagger and disc brakes.

>Not a funtime was had by me yesterday/today.
>
>Blew an alternator (that was the easy part), and then th AC Compressor
>bearing went... and 120 degrees in Redding, CA...
>
>Anyways, I had to get an Alternator at a partshouse and as they didn't have
>a good match and as mine are aftermarket I ended up with a 100 amp one that
>looked identical and fit like a glove.
>
>At idle the output volts were 12.9-13.4 which I considered to be quite
>normal when compared to my old one. Once I hit freeway speed though it
crept
>up to 15.2-15.8 at which point I disconnected it and kept running on GenSet
>as it was running anyways for the roof Air.
>
>I've never seen voltages that high and suspect I have a duff one but
thought
>I'd ask here before yelling at the parts store the next time I go Through
>Redding again.
>
>Running on the Genset sure was a bail-out as at least I got to Stockton
only
>8 hours late vs days.
>
>BTW, this was the first sizable distance trip with new four-bagger and disc
>brakes all around. Excellent on both counts. All the hassle re bleeding,
>etc. was definately worthwhile.
>
>I'll update my website when I get back, but first I have to get some work
>done and then I have to get back. Aside from the Alternator problem I'm
>currently running without dash AC as the compressor is bypassed with a
>shorter Serpentine Belt.
>
>Thanks in advance for info re Alternator volts.
>
>Heinz
>'76 Transmode - currently 'on-the-road'.
>