Alternator or??

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StevieC

StevieC

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Ok I'm about to take this stupid Journey of mine and drive it into a wall and buy something else. mad So after spending the money on an AGM Oddesey battery and verifying it was fully charged at 12.8 volts I installed it into the Journey. It held this voltage over night and now a few days later it's down to 11.5 volts. I know what you are thinking... Bad alternator... But hold one... Let me explain. I have 14.4 volts all the time while it's running and it never falls below 14 volts with all the accessories running at idle. I have checked for the voltage at the battery and at the back of the alternator. I have checked for voltage drops on the positive and negative sides of the charging circuits and this checks out. I even did a full field test and ran the car in this state at 2,000 rpm for 20 minutes and no change. It's like the alternator is keeping the volts where they need to be but not pushing enough current back into the battery which is weird because then it should struggle with all the accessories on at idle and it doesn't. Thoughts?
 
Something is draining it while the car is off. I dealt with this on the '03 and I bought a clamp-on ammeter, a Uni-t UT210E Made it very easy to clamp the positive battery cable going into the battery fuse box and start pulling fuses until the current dropped. It was $30 on ebay. Totally worth it over trying to break into the circuit with my DMM. It was always a pain and more often than not I would inadvetently lose power to the car, so then the electronics would cycle, flash the headlights, honk the horn, and there would go the 10A fuse in my DMM. I went through so many of those.
 
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.
 
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Originally Posted By: Quattro Pete
Did your car come with an AGM battery from the factory? Doesn't an AGM battery require higher charging voltage?
Optimally you'd want to have a higher charging voltage, yes, but Odyssey says its OK to run them at the lower voltage and will warranty them for the full term no problem.
 
Originally Posted By: Quattro Pete
Did your car come with an AGM battery from the factory? Doesn't an AGM battery require higher charging voltage?
No it didn't and I have tried 2 lead acids before this and had the same problem. There are other folks using AGM batteries in these vehicles no problem on the Dodge Journey forums.
 
Originally Posted By: Colt45ws
Something is draining it while the car is off. I dealt with this on the '03 and I bought a clamp-on ammeter, a Uni-t UT210E Made it very easy to clamp the positive battery cable going into the battery fuse box and start pulling fuses until the current dropped. It was $30 on ebay. Totally worth it over trying to break into the circuit with my DMM. It was always a pain and more often than not I would inadvetently lose power to the car, so then the electronics would cycle, flash the headlights, honk the horn, and there would go the 10A fuse in my DMM. I went through so many of those.
Nothing changes with the car off. Volts do not fall from fully charged state overnight. The only time the voltage falls is when the car is driven and then shut-down despite having a system voltage of 14.4 while running.
 
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Originally Posted By: Colt45ws
Originally Posted By: Quattro Pete
Did your car come with an AGM battery from the factory? Doesn't an AGM battery require higher charging voltage?
Optimally you'd want to have a higher charging voltage, yes, but Odyssey says its OK to run them at the lower voltage and will warranty them for the full term no problem.
Yeah but 11.5 volts is too low. 12.6 I would be fine with because that resembles a normal battery.
 
The only thing I can think of is the Alternator isn't pushing enough current but is stabilizing the voltage at 14.4. So it's not putting out enough to keep the battery fully charged and the cars demands all fed. I was thinking of clamping my amp meter claw around the battery charging cable on the back of the alternator and see how much current is coming out but I'm not sure if that would be accurate or if I need to do a full field trip along with this to see what the alternator is capable of putting out.
 
That doesn't make sense then. If there is 14.4 volts on the system, then the battery will gobble amps until its about 90%ish charged. After that its pretty much a trickle, but 11.5 OCV is very dead. My own experiance with Odyssey is that if they are well discharged, they will suck down so many amps that at idle the alternator will be wide open (full field) and only have 13.2-13.6V on the output instead of over 14 it really wants. The only reason it wouldnt charge like that was if there was resistance somewhere. When you checked voltage at the battery did you check on the actual posts or somewhere more accessable?
 
If it couldnt put out the amps demanded, the voltage would sag. Put variable load on it like an old school carbon pile tester and as you ramp up the amps, at some point it will be unable to maintain the voltage it wants and it would sag. If you went up high enough you could drop to where you start pulling power out of the battery too.
 
Originally Posted By: Colt45ws
That doesn't make sense then. If there is 14.4 volts on the system, then the battery will gobble amps until its about 90%ish charged. After that its pretty much a trickle, but 11.5 OCV is very dead. My own experiance with Odyssey is that if they are well discharged, they will suck down so many amps that at idle the alternator will be wide open (full field) and only have 13.2-13.6V on the output instead of over 14 it really wants. The only reason it wouldnt charge like that was if there was resistance somewhere. When you checked voltage at the battery did you check on the actual posts or somewhere more accessable?
On the Journey because the battery is buried in the wheel well they run a nice thick cables up to the shock tower as a boost points and then run other cables from here to the alternator / accessories etc. It is here that I tested the voltage. I know the posts are clean and the connections are tight because I just replaced the battery with this AGM Oddesey battery which was tested where I bought it and verified fully charged before I left with it because I was telling the guy the nonsense I had been through with the Journey with the lead acid's thinking they were at fault. I put a meter on the battery and did my own stress test on it at home before installing it and it was 12.8 volts. It also measured 12.8 once installed at the battery posts on the shock tower and it measured 12.8 volts at the back of the alternator as well with the car off before I started it for the first time. Then I had 14.4 volts at the battery cables and back of the alternator. Some days later it's down to 11.5 volts. It will hold whatever charged or shut-down voltage it has over night no problem so I know there is no parasitic draw from the vehicle or a bad diode in the alternator.
 
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Volt meter isn't the problem because it matches the meter on the battery charger. I think it's the alternator because this problem now has existed with 4 batteries. 3 Lead acid and now the AGM. If charged manually it holds the charge over night no problem and passes a stress test. Just airing it out here in case anyone had a similar "Weird" problem with their alternator to confirm it.
 
Before you give it up, check your battery terminal. My Dodge Ram pickup did this and it was a spacer on the battery terminal. The clamp bolts were tight, but you could lift the terminal right off of the battery. Took out the spacer and all is good.
 
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.
 
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