Charging problems

You guys might want to see if you can find some of my old posts. "Roughly" I tend to "think" the system into several areas....

1...Is the alternator good, large enough, and capable of full output?

2...Is the regulator good

3...What is the voltage drop so far as heavy charging current from alternator to battery?

4...What is the voltage drop from battery, through all connections, harness, ignition switch, etc, to the VR? This will cause over voltage

5....What is the condtion of the ground paths? That is the ground path from alternator/ engine block/ battery NEG?

Second, the ground path from VR mounting to battery NEG?

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To check some of this stuff:

1 and 3, alternator condition and charging line drop:

Set up with voltmeter, a way to vary idle screw, and with engine running fast, jumper the field to battery so it charges "full." That is, disconnect the field connection, and hook a good jumper wire from the alternator field direct to battery.

"A quick check" is to speed up the engine until the battery reads say, 15.5, and turn on all the loads you can. Lights, heater, etc. You should be able to diddle with the idle screw and keep the engine above 14V This will not give you "full output" capacity, that is, whether you have a 35A or 60A or whatever, but it WILL tell you if the one you have is capable.

Now, with battery voltage noted, switch your NEGATIVE probe over to the alternator output stud, leaving the pos probe on the battery positive.

This will give you the voltage drop through the harness on the charging line. Check this with lights, heater, etc, powered on. The voltage reading should be "the lower the better" and not over 1Volt. Lower is better. Higher voltage indicates problems at the bulkhead connector and ammeter.

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If this much looks OK, move to voltage drop at the voltage regulator. "Normalize" system connections, IE remove jumper, re-connect regulator wire at alternator, and see if it's charging and what the battery voltage is. If it does not appear to charge, and or voltage is below 14 and certainly below 13--13.5, then it may be VR

Now disconnect VR connections, and jumper them together. Again run the engine and see if the system will charge. This is AGAIN full field condition, just like the first test. If the thing charges, replace the VR

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With a new VR the system should be looking more normal. Now check for voltage drop in the field circuit.

With the key ON but the engine NOT running, stick your meter probe onto the VR "IGN" terminal. Stab the other into the top of the battery POS post. You are hoping for a very low reading. If the reading is more than .3V (3 tenths of one volt) you are suffering voltage drop in the harness, bulkhead connector, or ignition siwtch. You MUST chase this down, as more and more drop in this path will cause over voltage / over charging at the battery

You can confirm this happening by monitoring battery charging voltage. ANY drop measured in this circuit will ADD to charging voltage. In other words if you measured 1.5V in the test above, and the VR is correctly charging "trying" to charge at 14V the battery willl actually see 15.5 V when running.

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Last check the VR ground path.

With the engine running, stab one meter probe into the battery NEG post. Stab the other into the metal mounting flange of the VR. You again should read VERY little, and zero is perfect. IF not the ground path needs to be improved, AKA body grounding to battery NEG