Chrysler Repair: Charging System Evaluation, dodge grand caravan, rpm 2000

Question
QUESTION: I have a 94 Dodge Grand Caravan. I have alternator replaced today because the voltage is about 13.2 - 13.3 when all accessories "ON" running rpm=2000. Voltage will show 14.6 when the car started, and it will drop quickly to 13.6 within couple seconds. Voltage reading when idle with all accessories ON is 12.7 - 12.8 (Occasionally drop to 12.4 for few seconds). Unfortunately, the reading is the same with this "NEW" alternator (NOT REFURBISHED). I did research on Internet, and found out that this regulator is external (It is actually part of the computer of the car). Is this voltage reading normal? What is volage supposed to be read? Any guideline or exact specification should be match? The car is running fine with no engine light or anything wrong. I just want to be on the safe side, because this car has a special seat installed for disability elder. Any advice, I will be appreciated.

ANSWER: Hi Woodman,
Recall that the battery voltage is nominally 12, and that the maximum recommended charging voltage is about 13.6. So without going into all the details of how to test a charging system my evaluation of your reading is that they are in the acceptable range. The technical specs depend upon what is the battery temperature and the current draw and vary depending upon the model of generator. It also requires a known resistance sink and an ammeter to fully evaluate. But so long as the voltage is above 12, you don't have a charge warning light "on", and there are no fault codes related to the system store in the computer memory I would be satisfied. You can check for fault codes using the ignition key: "on-off-on-off-on and leave on" doing that in 5 seconds or less lapsed time. Then watch the check engine light, which remains "on" to begin to flash, pause, flash, etc. Count the number of flashes before each pause, then repeat for accuracy of the counts. Then group the counts in pairs to form the two-digit fault codes. The last such code is 55, which means "end of readout". I would ignore a 12 code which is caused by disconnecting the battery. Only the codes 41,46,47 are related to the charging system. So absent those, everything is fine.
Roland

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QUESTION: Is any factory service manual that will specify the exact voltage reading for Grand Caravan 3.0 engine coming out from the 90 Amp alternator when I take the vehicle to a shop with the ammeter? What should they read with the ammeter connected?

Answer
Using the procedures described for the test equipment and the shop manual, the output should be about 90 amps with the engine running at 1250 rpm and the coils of the generator "full fielded". The only voltage test specific for the generator is the 'output wire resistance' test which is again a technically specific test as to the voltage drop across the unit at 20 amp current flow.
So long as the current output meets spec, the voltage is higher than that on the battery but does not exceed 13.6V, you are fine.  All that is really necessary is that the voltage exceed that of the resting battery and there is net positive charge going back into it under all operating conditions. There is no other guidance I can offer.
Roland