where's the voltage regulator??

[Vee]

I'm having issues w/ my charging system. changed-out the alternator last month, voltage checked good w/ my cheapo multi-meter at about 14/15 when engine idled. but a couple days ago, my rig died again. had to get a jump start and when I got home the battery was dead and I checked the water level it was very low, filled it w/ distilled h2o and trickle charged it, now it's got 12.1 volts (borrowed a nice volt meter) but when running I'm only getting 13.3 volts. I took the alternator back to Autozone and they ran it on their tester and were getting 15+ volts. looking at my Hanes book and it mentions checking the voltage regulator, but of course doesn't mention or show a pic of where it is. any help would be appreciated. my friend says Chevy's usually run around 13 volts anyways - is that right?

 

[4X4HIGH]

It is inside the alternator if this is for your 81 K5

 

[toomany]

my friend says Chevy's usually run around 13 volts anyways - is that right?

A properly functioning charging system should have around 14.7 volts...regardless of make.

If you're having problems with the truck dieing, it could be the battery. Your coment about having to add water to the battery got me to thinking. I didn't know they even sold that style still...other than for small stuff (bikes, mowers, etc).

 

[dyeager535]

Auto places check voltage no differently than you would, with a voltmeter on the output lug.

If idle RPM is low, output will be low. They may be testing it at an RPM that is not your idle. Makes a big difference on the older alternators. Increase the RPM's and watch it. Also turn on the heater/ac, headlights, radio, etc., and measure again (before/after) If it's not above 13V, there is a problem.

Where did you test voltage on your truck? You need to check it at the charging lug on the back of the alternator first, as anything read past that point COULD be influenced by bad connections, etc.

 

[Vee]

It is inside the alternator if this is for your 81 K5

that's what my friend thought, but my old Ford (sorry ) had an external one, and the Hanes manual makes it sound like there's an external one that can easily be checked

 

[Vee]

A properly functioning charging system should have around 14.7 volts...regardless of make.

If you're having problems with the truck dieing, it could be the battery. Your coment about having to add water to the battery got me to thinking. I didn't know they even sold that style still...other than for small stuff (bikes, mowers, etc).

it's wierd to me that I was getting 14/15 volts when I 1st installed the new alternator last month and now am only getting 13. the battery isn't that old, maybe 5 yrs, but it has the caps that you can pop open to check water level - they were low, so I filled em. the battery has held a consistent 12+ volts for the past couple days after I charged it

 

[Vee]

Auto places check voltage no differently than you would, with a voltmeter on the output lug.

If idle RPM is low, output will be low. They may be testing it at an RPM that is not your idle. Makes a big difference on the older alternators. Increase the RPM's and watch it. Also turn on the heater/ac, headlights, radio, etc., and measure again (before/after) If it's not above 13V, there is a problem.

Where did you test voltage on your truck? You need to check it at the charging lug on the back of the alternator first, as anything read past that point COULD be influenced by bad connections, etc.

I tested the voltage on the alternator itself, it registers the same reading as on the battery leads, so my connections seem to be good. I'll have someone step on the gas pedal to increase RPM's and check it again.

 

[4X4HIGH]

that's what my friend thought, but my old Ford (sorry ) had an external one, and the Hanes manual makes it sound like there's an external one that can easily be checked

GM alternators had an external regulator back in the day (until the early 70's) since then GM has made the alternators with an internal regulator.

A battery that is 5 years old is actually at the point of needing replaced especially since you found it low on electrolyte. Regardless if you aren't seeing between 14.5-15.5 volts at the main lug of the aternator then it isn't charging properly and either the aternator itself or the regulator within is bad. Take the alternator to be tested at a place other than where you bought it (where you bought it might not want to find it bad since they will have to replace it if it shows up bad).

 

[badmix]

HEre are is my nickles worth of info

1) 12.1 volts is a DEAD battery, a properly charged battery without truck running should be in the 12.6-12.75 range

2) 5 years is the life of a battery time to replace

3) volt reg is internal

 

[Vee]

my father-in-law told me about a shop that'll check the entire system for free - looks like that's where I'm headed - anyone want to watch my 2 toddler's while I go?

 

[chulisohombre]

need new battery

definitely need a new battery.it is at the end of its life at 5 years.most batterys only have a 5 year guarantee.as was said if it was out of water its been needing replacement for a while.those capa are supposed to only be for venting the batrtery.not to replace the liquid inside.at least thats what i was told.so ive never opened them.the older batterys and motorcycle/lawnmowers have the fluid caps for replacing fluid in them.if you added water and no electrolite into the battery it will not charge across the cells of the battery equally also.the older trucks had external regulator that hooked into the back port of the alternator and sat on the front right side of the core support opposite of the battery.i think they stopped having that a nd went to internal in the mid seventies.so you should not have that on yours at all.some auto store testers dont have a rpm guage to test the alternator.you need to make sure they are testing it at around 1000 rpm.should give at least 13.5 volts at idle and then up to 15 at high rpm.let us know how that works for ya.i think it was auto zone that had the tach attached to the tester when i took one there.