alternator will not charge without being rev. to high rpms

[Texas wagoneer]

I have had this problem for a while where the alternator will not charge or show a charge without being rev. to high rpms. I even have changed out alternators' and the problem is still there. I dont know what to do.....I am afraid that I will for get to rev the engine some time and I will have a dead batt. It does charge because the engine will run without having the batt. cables conected. After rev. the engine, the lights and electrical parts all seem to glow and run better after the sudden boost of power....I need help

[Joe Guilbeau]

Nope. you need a new alternator regulator that creates a field magnetism at a lower rpm, and by the way, NEVER test the vehicle by removing any battery cables, not a good idea for 4 or 5 reasons.

Reason #1 Without a way to monitor the Positive Battery voltage the regulator is in limbo, and who knows what it will do to it's output.

Reason #2 With the newer alternators you have just blown up the regulator circuit (CS-Series)

Reason #3 With the alternator's regulator circutiry searching around in open loop mode, who knows what that sensitive MSD or Electronic Ignition is getting. Soon you will be posting about the POS electronics in your vehicle.

Reason #4 The unexpected spike that will occur when the battery post is removed is very damaging to any electronic or electrical component attached to it.

Reason #5 Any outgassing of the battery will supply the third necessary component for an explosive scenario, namely spark, as you will have the outgassing, the oxygen and then the spark.

Anyhow, you have probably damaged the diodes in the regulator circuit as they do not cope too well with these types of transiets, and they are on their way to failure...namely leakage.

On your alternator, it is not uncommon to have regulator circuits installed that need to see 2000 RPM's in order to energize the magnetic field in order for the stator to begin to see an induced voltage, expecially with somewhat heavy loads during starting, winter heater usage and additional light loads, along with that spankin stereo...

Do an assessment of the amperage load when the vehicle is running at night, and then take a look at the pathetic amps output your stock alternator is probably generating at 1600 rpm's.

A 72-amp 10-SI is generating around 10 amps.
A 63-amp 10-SI is generating around 25 amps.

A 66-amp 12-SI is generating around 23 amps.
A 78-amp 12-SI is generating around 23 amps.
A 94-amp 12-SI is generating around 32 amps.

So, headlights are at least 15-20 amps, and that doesn't leave much for the heater, ignition, and stereo's.

If you are anywhere around San Antonio, drop me a line and we can get you all set up for very little outlay.

[Chevelleguy]

Yep, what Joe said.