2001 Dodge Grand Caravan- Experiencing charging difficulty. Replaced
battery about 2yrs ago, and the alternator made some noise this summer at
low idle. I tried with amp probe and multimeter to locate problems. The
battery charge 12.4V and with the engine running 13.5V. I've tried
disconnecting the neg. battery cable with engine running, it died. Amp
Clamp at the alternator shows about 35amps with everything running, but it
doesn't struggle- radio, a/c lights seem to run perfect. Tension on the
belt seems fine and the noise at low rpm is not there. Could it be the
alternator or pmu or could there be another drain wire and how could I
To avoid going into a lot of details, I would recommend that you take out the
alternator and have it confirmed being faulty, most auto parts stores will do
this free of charge. The alternator you have will put out at least 90amps. I
believe that with "everything on" the Alt. should have been putting out more
You should not do this, you could harm the electrical system with the surge.
Anyway there is usually a short delay before the system will pickup the
voltage drop, so usually the engine would usually conk.
You are doing something that used to be ok with the older cars.
A fully charged battery should be about 12.66 volts with zero load on it. 13.5
volts charging is about minimum for a healthy alternator working with a good
battery. Try putting an 2 Amp overnight trickle charge on the battery to bring
it up to full, disconnect charger, wait 3 hours and read the battery voltage. If
you don't have at least 12.6 volts, the battery's bad. If the 12.6 volts IS
there, it may be a weak alternator, VR, VR pigtail, or ground leads & other
Somebody is quoting from a book, which is ok but does not give the field
experience necessary. Although I agree that the "standing" battery charge is
a little low at 12.4, it could be attributed to cranking and will still
operate the vehicle, unless it drops to 12volts or less after a little
cranking (which does not seem to be the problem here). It does not matter
what kind of charge you put to it, although the preferred would be 40amps for
Yes, there could be a lot of reasons, but do you know what the VR stands for?
It is in the alternator, which would mean Faulty Alternator.
Sharon K.Cooke wrote:
Message posted via CarKB.com
When my car/truck batteries get to the point where the standing overnight
voltage drops to 12.4 volts consistently (in warm weather), it's time for me to
start looking for the source of the problem, which is usually just an aging
battery that's losing its ability to hold a full charge.
You can throw a 40 Amp/one hour charge on there if you want to, but it's
generally considered (by automotive engineers) to do an overnight trickle
charge, since that will sometimes de-sulphate an aging battery. Your suggested
method will likely kill some of the remaining life in an aging battery but, to
each their own.
Yes, I know that VR = Voltage regulator, and that the VR is integral to the
alternator, but it doesn't follow that a bad VR is an alternator problem just
because it's attached to the alternator. I have replaced a so-called "internal"
VR before, without touching the brushes, windings, bearings, etc. of the
alternator itself. A little more work than replacing an external VR, but not
much. I've even modified a "high output" (160A) alternator with an internal VR
to work with an external VR so I could beef up the current output on an old
Actually, it's not.
I may be off a bit but the last mini van that used an integral
voltage regulator would have been a 1987 with the Mitsushitty
2.6, everything since then has had the voltage regulator
incorporated into the PCM (engine computer).
No need to take the alt off to have it checked, you just did that, its
charging!!! Load test the battery, more then likely it is at fault causing
the problem....(assuming you put the amp probe at the battery)
Keep in mind that this is an OBD2 system, If there were a problem with the
alt output the check engine lite would have been turned on for a charging
It is not a good practice to remove a battery cable from the battery while
the engine is running, thats a good way to fry components that are being
used when this is done.
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