Question about charging systems...

[bigvinnie]

Here's the scenario:

From a cold start, volt meter shows 14.5 volts output at the alternator, then gradually drops to 12 volts after a few minutes, which I assume indicates that the battery is back to full charge, but I thought it still should be putting out more than 12 volts to run the accessories while the motor is running...???

Reason I ask is cuz I'm trying to figure out a problem with the starter acting sluggish after the engine is warmed up... I first thought it was a problem with the charging system, but it may be a heat soak problem with the starter...

Does it sound like the charging system is acting normally..???

Alternator is a fresh rebuild and voltage regulator is new.

Thanks a heap.

[rage'nrat638]

CLEAN BATTERY TERMINALS
ATLEAST TWO GROUNDS FROM ENGINE TO FRAME
CHECK THAT GOOFY LITTLE TERMINAL ON THE PASSENGER FENDER
NEXT TO THE BATTERY FOR THE HEAD LIGHTS ....CLEAN TERMINALS
TERMINALS GOOD AND TIGHT ON STARTER
TIMING SET CORRECTLY

Going to be upgrading to a internal regulated alt. soon my self...
just don't care for the way things seem to flicker at idle...
with the old system....
grounds are so important on these trucks....
the front turn signals only have one wire (power) so the front
rad. support has to be grounded good for them and many other things like that to work all full capacity.

i know...where am i going here....
that starter would have to be mighty hot ....to be a heat soak problem....

[dinnut]

is it possible that your timing is too far advanced... this will cause a slow crank when warm

[bigvinnie]

Thanks for the replies, hadn't considered the all-important ground factor, will check those and see if that makes a difference...

As far as timing, it's dead on at 8 degrees, plus it starts fine when cold...

Once again, does it sound like the charging system is behaving normally, or should the alternator be putting out more than 12 volts at all times...???

thanks

[Andy4639]

14 to 15 Volts all the time when the truck is running. If it falls back to 12 after a while it's more than likely your voltage regulator. You said it is 14.5 at the alternator, what is it at the battery, that's the key? If it isn't 14 to 15 at the battery, than you have either a wire or regulator malfunctioning. You said both the regulator and alternator are new and rebuilt, I have seen countless regulators no good at time of purchase. Alternator should be good since it reads 14.5 at start up.
For your starter delima, it sounds as if your battery isn't getting fully charged and that it wont turn over the starter. Fix the voltage first and I bet the starter problem will go away. Hope this helps.

[Huck]

If the battery is fully charged, and the starter cranks poor when warm--but fine when cool--I personally would swap out the starter as that is a VERY common problem with chevy trucks/cars. The starter area gets too hot and starts to build resistance in both the solonid and the starter. They make a heat shield for the starter that can reduce this problem but most don't bother to buy-install this as you can buy a starter with a lifetime guarantee for about the same money! Can't tell you how many I've seen -----lots. My strucks show about 14V at initial start then drop down to about 12.5V once run a while. Gounds are extremely important and often taken for granted but can drive you nuts so make sure they are good as well. Let us know what you find---.

[BLACK AND BLUE 67-72]

Sounds more like a starter problem to me, the alternator will drop off after charging for a while, if it charged at 14.5 volts constantly then it would overcharge the battery! Mine has a new alternator w/internal regulator, and a new battery, and it will charge at 14.5 when first started and it gradually drops off as it runs, dropping to around 12.5 volts. I have headers on my truck and I have never had a problem with starting or having a battery go dead with it charging in this way.