Before giving in and buying a alt. I know its a PITA but it might be worth it to check the voltage right on the battery terminals with the engine running. Id hate to hear you threw an alt in it and not fix the problem.
Alternator or??
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Originally Posted By: StevieC
Originally Posted By: rollinpete
Hope you find what's wrong and let us know, electrical stuff is the worst....
I've seen some weird stuff but this one takes the cake. Proper voltage, powers all accessories at idle, won't charge the battery but I can charge the battery manually no problem through the same cables.
About 5 years ago I had similar symptoms on a John Deere tractor. My feeble electrical skills told me that the battery and alternator were good, yet the battery would drain down while it was operating. Somehow, I finally diagnosed that a $25 relay was bad somewhere in the electrical system and that fixed it. I speculated that a broken light wire that shorted out (blown fuses) probably wrecked that relay at some point.
Sorry I can't help anymore. I guess my point is to diagnose the alternator(and everything else) correctly before spending money on a new one, only to find out that was not the problem. Did you have any electrical problems recently that might be tied in to this current problem?
Originally Posted By: rollinpete
Hope you find what's wrong and let us know, electrical stuff is the worst....
I've seen some weird stuff but this one takes the cake. Proper voltage, powers all accessories at idle, won't charge the battery but I can charge the battery manually no problem through the same cables.
About 5 years ago I had similar symptoms on a John Deere tractor. My feeble electrical skills told me that the battery and alternator were good, yet the battery would drain down while it was operating. Somehow, I finally diagnosed that a $25 relay was bad somewhere in the electrical system and that fixed it. I speculated that a broken light wire that shorted out (blown fuses) probably wrecked that relay at some point.
Sorry I can't help anymore. I guess my point is to diagnose the alternator(and everything else) correctly before spending money on a new one, only to find out that was not the problem. Did you have any electrical problems recently that might be tied in to this current problem?
Thanks I'll check that.
OVERKILL
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Originally Posted By: StevieC
Originally Posted By: OVERKILL
Run the vehicle. Unhook the battery. Let it sit overnight, what's the voltage at in the morning?
There is no draws, I have done this. When I charge the battery to the AGM required 12.8 volts it is still 12.8 volts in the morning. I can then do a stress test on it and it will snap right back. I have then hooked the car to it and checked it and it's still 12.8 in the morning.
It's definitely a charging problem.
What is it at immediately after you drive it though? The draw could be intermittent.
Originally Posted By: OVERKILL
Run the vehicle. Unhook the battery. Let it sit overnight, what's the voltage at in the morning?
There is no draws, I have done this. When I charge the battery to the AGM required 12.8 volts it is still 12.8 volts in the morning. I can then do a stress test on it and it will snap right back. I have then hooked the car to it and checked it and it's still 12.8 in the morning.
It's definitely a charging problem.
What is it at immediately after you drive it though? The draw could be intermittent.
Switch the alternators sense and excite wires and this will happen.
Right at Shut-Down 13ish and then it slowly recedes to the resting voltage.
Originally Posted By: Donald
Switch the alternators sense and excite wires and this will happen.
It's in one connector.
Switch the alternators sense and excite wires and this will happen.
It's in one connector.
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OVERKILL
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Originally Posted By: StevieC
Right at Shut-Down 13ish and then it slowly recedes to the resting voltage.
So it shows 13.xx at the battery and then drops to 11-something?
Right at Shut-Down 13ish and then it slowly recedes to the resting voltage.
So it shows 13.xx at the battery and then drops to 11-something?
Yes 13ish and then drops by .1 of a volt every few seconds until it rests at 11.5 Whether connected to the vehicle or not.
If I manually charge then it stays at 12.8 after it falls from the chargers 14.7 volt charging voltage. It will hold 12.8 over night and it will hold the 11.5 over night as well from the cars charging system if I try that instead.
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I'd also check for AC ripple voltage at the battery terminals. That needs to be minimal too. Large variations could indicate failing diode(s), which can simulate an undercharged battery. My car has been doing something similar and I show decent alternator voltages, currents, and resistances. Yet the next day my battery drops to 12.3 volts (will not charge above 12.6v on my battery charger). While there is a draw of some sort, it has eluded me. With the car at idle and all accessories on, my idling battery voltage drops from 14.2 (no accessories) to 13.8v. Which is fine. It's confusing to me since the accessories don't draw all that much. When I put the battery on a charger it starts out at 8 DC amps down to 4 amps over 45 minutes. At that point, the charging current will not drop (suggesting a real 4 amp draw). Logically, a 4-5 amp draw should KILL the battery within 24 hours. And there are no 5 amp running loads in the car. The car runs and starts fine all the time, even after sitting for 2-3 days. The battery is only 1 year old. The alternator is 16 years old.
What kind of fluctuating A/C voltage should it be reading on the volt meter?
1/2 A is enough to drain a sitting battery over a few days. Chances are the normal memory plus a glove box light or something. If you have an ammeter, i recommend using it to establish the draw before I went further
On the Caravan's the wires under the battery tray and the ground wire are know weak spots that cause issues like the one you describe.
I would have a look at those wires in addition to the other suggestions provided.
I would have a look at those wires in addition to the other suggestions provided.
I should also mention that the Chrysler dealer in Florida changed this alternator about 40,000km ago when I was on vacation and it died on us. At that time it wouldn't charge at all. I know they replaced the alternator and the clutch it has on the pulley.
We verified that the clutch is working and not the cause.
We verified that the clutch is working and not the cause.
OVERKILL
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Originally Posted By: StevieC
Yes 13ish and then drops by .1 of a volt every few seconds until it rests at 11.5 Whether connected to the vehicle or not.
So to confirm, you've run the vehicle, verified 13.xx at the terminals, physically disconnected the battery (which I know from your other thread is a monumental PITA) and let it sit overnight and it still dropped down to 11.xx?
Just want to confirm we aren't dealing with some sort of intermittent phantom draw here.
Comically, ages ago I had the alternator poop the bed on my F-250. It was showing far too high voltage on the gauge (like 16 or something close) and then would promptly kill the battery overnight. Not the same scenario, but a failing alternator can have some fun symptoms.
Yes 13ish and then drops by .1 of a volt every few seconds until it rests at 11.5 Whether connected to the vehicle or not.
So to confirm, you've run the vehicle, verified 13.xx at the terminals, physically disconnected the battery (which I know from your other thread is a monumental PITA) and let it sit overnight and it still dropped down to 11.xx?
Just want to confirm we aren't dealing with some sort of intermittent phantom draw here.
Comically, ages ago I had the alternator poop the bed on my F-250. It was showing far too high voltage on the gauge (like 16 or something close) and then would promptly kill the battery overnight. Not the same scenario, but a failing alternator can have some fun symptoms.
Originally Posted By: StevieC
Yes 13ish and then drops by .1 of a volt every few seconds until it rests at 11.5 Whether connected to the vehicle or not.
What on earth?
Sounds like a shoddy battery.
You'd have to be using hundreds of amps to drain a (good) battery fast enough that it'll get down to 10% charge in a few minutes.
Can you just borrow a cheezy normal known-good lead acid battery and see how it works?
Yes 13ish and then drops by .1 of a volt every few seconds until it rests at 11.5 Whether connected to the vehicle or not.
What on earth?
Sounds like a shoddy battery.
You'd have to be using hundreds of amps to drain a (good) battery fast enough that it'll get down to 10% charge in a few minutes.
Can you just borrow a cheezy normal known-good lead acid battery and see how it works?
Yes I disconnected the battery from the vehicle after the vehicle charged it and at shut-down it was 13.xx surface voltage at the battery and then within about 10 minutes it will creep down to 11.xx and stay there over night.
If I manually charge the battery using 14.7v and disconnect it will fall to 12.8v and stay there overnight either connected to the vehicle or disconnected from the vehicle.
If I manually charge the battery using 14.7v and disconnect it will fall to 12.8v and stay there overnight either connected to the vehicle or disconnected from the vehicle.
Voltage with vehicle running. (At Battery)
A/C Volts read at the battery while the vehicle is running. (Charging)
Voltage immediately after shut-down. (At Battery)
Voltage showing that it is creeping down from above voltage toward the 11.5 (Takes too long so I just snapped this here but it's less than 12.6v (flooded) / 12.8v (AGM) where it should be at the minimum for a fully charged battery)
A/C Volts read at the battery while the vehicle is running. (Charging)
Voltage immediately after shut-down. (At Battery)
Voltage showing that it is creeping down from above voltage toward the 11.5 (Takes too long so I just snapped this here but it's less than 12.6v (flooded) / 12.8v (AGM) where it should be at the minimum for a fully charged battery)
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And yes I know this is a terrible voltage meter but it is accurate. I verified it. Also I'm using a bigger charger to charge the AGM not the NOCO Genius you see in the picture which is only 3.5a
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