Weird charging behavior

[JHZR2]

Hi,

Im tracking a likely very weak battery on my 98 S10.

It charges good, alternator puts out 14.4-14.7V, but after sitting for a while, the battery will be down to 12.2V or less.

It goes down to the 8's when cranking. Ive been charging it and driving it, so havent put my Cen-tech or carbon pile on it yet...

But this evening, after only sitting a little bit, I started the truck, and the voltage didnt go up to 14.x like it usually does (instantly). Rather, it slowly crept, 12.5, 12.8, 13.1, 13.4, 13.7, 13.8, 14.1, 14.4, 14.7. Then it was steady.

But it took a few seconds. Not instant like it has always been.

Now my truck used to sit for very long periods. At one point before I knew much, I was trying to trace down what I thought was bearing noise, and put in a remanned Autozone alternator.

It seems to work fine, but maybe it has an intermittent flaw ow something.

Any thoughts on this behavior? First time ever that this has happened.

Thanks!

 

[Audios]

Test the battery as soon as you can, trying to charge a dead battery will kill your alternator long term.

 

[oilboy123]

One thing I know is batteries can make you think all kinds of things are going on. Battery, Alternator, Starter. It all starts with the battery as the backbone. A battery can lead you on a wild goose chase. It's also the most likely of the three to have a problem.

 

[JHZR2]

Yeah, I will. I have a real charger on it now, because it has a maintenance mode desulfidation process. Hope to see if that helps.

The battery is a walmart Maxx, less than a year old, JCI made. Dont know why it would be bad...

Its funny though, because I pulled in my truck and put the charger on it right away. Most of the time on batteries, the charger will "charge" the battery for a long time before it actually goes to float mode. This battery very quickly went to float, almost indicating that it is accepting very little charge and then appearing "full".

 

[Quest]

undo the battery terminal post and then charge the battery with a slow AC charger. When done, load-test with a carbon pile tester to verify the status of your battery.

If the battery is good, then suspect something to do with parasitic current draw somewhere in your car's electrical system.

Q.

 

[JHZR2]

Originally Posted By: Quest
undo the battery terminal post and then charge the battery with a slow AC charger. When done, load-test with a carbon pile tester to verify the status of your battery.

If the battery is good, then suspect something to do with parasitic current draw somewhere in your car's electrical system.

Q.


Thing is, the battery is a side terminal type, and IIRC you arent supposed to use steel posts to test a battery. What to do??? Can one get lead screw in lugs?

 

[JimPghPA]

Originally Posted By: Audios
Test the battery as soon as you can, trying to charge a dead battery will kill your alternator long term.


+1

Many alternators now days do not have the extra capacity to charge dead or almost dead batteries without being damaged.

You would be much better off using some kind of a trickle charger if you must keep that battery.

BTW, It use to be (not as much of a problem now days as before, but still possible) that if you jumped started a bad vehicle with the good vehicles engine running, there was a good chance of damaging one or more of the diodes in the three phase bridge rectifier diode output, and those diodes would often fail is a way that they would have a high amount of leakage. This would act as a constant load on the battery. This would show up like a weak battery, and if you let it set for a few days the battery would go completely dead.

So if anyone has used your vehicle to jump start another vehicle and you vehicle was running when the engine of the bad vehicle cranked, then there is a slight possibility that your alternator is now bad, and draining the battery.

 

[Donald]

Was this one of the days when it was very cold? I started my Suburban on Sunday morning (when it was below zero where I am) and the voltage gauge was way down in the 9 or 10 V after it started. It started with no problem. I opened the hood to make sure there was a belt.

I am not quite sure what was going on, but the PS did not want to move easily either. I let it warm up for maybe 15 minutes and when I went out, everything was fine.

I my case unsure if it was the alt. or gauge or what. Now if I had been real curious, I could have used my DVM to check it out, but I was not overly interested in taking my gloves off to fool with a DVM.

 

[JHZR2]

Originally Posted By: JimPghPA
Originally Posted By: Audios
Test the battery as soon as you can, trying to charge a dead battery will kill your alternator long term.


+1

Many alternators now days do not have the extra capacity to charge dead or almost dead batteries without being damaged.

You would be much better off using some kind of a trickle charger if you must keep that battery.

BTW, It use to be (not as much of a problem now days as before, but still possible) that if you jumped started a bad vehicle with the good vehicles engine running, there was a good chance of damaging one or more of the diodes in the three phase bridge rectifier diode output, and those diodes would often fail is a way that they would have a high amount of leakage. This would act as a constant load on the battery. This would show up like a weak battery, and if you let it set for a few days the battery would go completely dead.

So if anyone has used your vehicle to jump start another vehicle and you vehicle was running when the engine of the bad vehicle cranked, then there is a slight possibility that your alternator is now bad, and draining the battery.


Nope, nothing like that. But given your comment, I assume that jump starting is a no-no, and that one should just use a fresh battery (or disconnect the battery from the good car and just connect it directly with jumper cables?

One should not provide a jump start then?

 

[ahoier]

Check the cells....are all the caps level with fluid? If they are not, add distilled water (or filtered/drinking/bottled water....in a pinch...) to the cells to make them even....take it into Walmart, and have them take a look at it.

It's a Maxx battery, you still got an active warranty right? If it's bad, they'll replace it....no big deal really.....

If possible, bring the whole vehicle down there.....so they can do a charging system test on the vehicle too while it's out there....they can check the alternator, starter, and battery under loads.

 

[AdRock]

Originally Posted By: JHZR2
Originally Posted By: JimPghPA
Originally Posted By: Audios
Test the battery as soon as you can, trying to charge a dead battery will kill your alternator long term.


+1

Many alternators now days do not have the extra capacity to charge dead or almost dead batteries without being damaged.

You would be much better off using some kind of a trickle charger if you must keep that battery.

BTW, It use to be (not as much of a problem now days as before, but still possible) that if you jumped started a bad vehicle with the good vehicles engine running, there was a good chance of damaging one or more of the diodes in the three phase bridge rectifier diode output, and those diodes would often fail is a way that they would have a high amount of leakage. This would act as a constant load on the battery. This would show up like a weak battery, and if you let it set for a few days the battery would go completely dead.

So if anyone has used your vehicle to jump start another vehicle and you vehicle was running when the engine of the bad vehicle cranked, then there is a slight possibility that your alternator is now bad, and draining the battery.


Nope, nothing like that. But given your comment, I assume that jump starting is a no-no, and that one should just use a fresh battery (or disconnect the battery from the good car and just connect it directly with jumper cables?

One should not provide a jump start then?


If you give someone a jump just make sure your vehicle isn't running. And don't start yours back up until the cables are removed.

 

[HTSS_TR]

When I give someone a jump I have my engine running at 2-3k RPM for 20-30 seconds, then turn of the engine before the other car try to start.

 

[ltslimjim]

^This.

I did it wrong on my first try, though. My car was dead this past spring from headlights being left on for 3 hours(it was raining, daytime...no warning sound for headlights in this car, so I just forgot)...

Thankfully I was visiting a friend with his Titan, plenty of juice. Connected the jumper cables to both batteries, while his truck was running for about 5 minutes. Started up and immediately removed the positive > negative from his truck.

Next time I'll disconnect before attempting to start. He had a new battery, but no ill affects so far. My battery needed topping off at each cell near the posts(one by the positive and one by the negative).

I had it checked this past summer at an Interstate Battery location, it was down about 14% from the factory CCA so I think it's got plenty of life left. The voltage reading with the car on at the battery terminals was 14.1-14.2v, so I believe the alternator is putting back fine. The factory calls for around 410 CCA for this car, so it's right there at it currently from 465-475 in this Die Hard originally. My car has a 'fuel eco' mode on the alternator, so it's not putting back at full capacity until under a certain load.

As for the OP, a parasitic draw test would be worthwhile for a checked off your list sorta thing(peace of mind):

 

[JHZR2]

Yeah, I can do a parasitic draw test.

I did notice something else odd this morning. I had put my battery on a charger (I have a charger connection hardwired for ease of doing this kind of thing), for overnight.

This morning, I went out the door and it was dark out. Now, I have a scangauge permanently attached to my OBD port. No big deal, right? Well, I noticed that the scangauge kept lighting up. It displayed my normal items, and showed ignition at 34, load at 19, TPS at 0, etc. Weird. The truck was off.

I had a volt meter in the cigarette port, so I was able to watch it. My charger was floating the battery, but the voltage kept fluctuating between 13.8V and 14.3V. When it would go over 14V, the scangauge would light up. After a bit, the voltage would drop into the 13's, and then the scangauge would go out.

Any idea what this means? Weird that the ECU would be energizing such that the scangauge would be turning on. I disconnected the charger obviously. But any ideas????

 

[friendly_jacek]

The initial description of battery charger going to float too quickly sounds like sulfated battery. If the truck mostly sits idle and there is a parasitic drain, that could have sulfated the battery in short time.

You can consider equalizing the battery. It's basically a controlled overcharge. Make sure the cells are full and battery doesn't overheat.

The last post about the scangauge sounds weird. I don't have one to confirm if abnormal. You could try a similar scenario with a different car.

Maybe the ECU needs to be reset or is defective? Could the scangauge be defective?

 

[eljefino]

Your obdii port always has power. The scan gauge assumes when it sees 14 volts, that you are running, and it lights up. For grins, consider that thing a parasitic draw, and leave it unplugged.

I agree with others that your battery is NFG. My dakota's is in the same boat, with a click-no-start, then 15 minutes at 6 amps of charging it kicks right over. As a 4th vehicle it only sees dump duty every other week.

I think your battery is a jeckyl and hyde, first drawing tons of power so that your system voltage was low, then hardly any.

Standard 3/8" bolts from the hardware store make fine testing contacts. The little bolts in your cables are made of steel; I know of no problems between steel and lead. If you want to get fancy some 3/8" nuts and lock washers threaded 1/4" up said bolts will keep them from bottoming out, potentially bad for the battery.

 

[meep]

you likely have a dead cell in the battery. Alternator sounds fine to me. ramp-up voltage is just the alt overcoming the low battery, and also could be part of ecu programming.... some ramp the alt up on cold start.

quick & dirty test. if you want definitive, disconnect the battery, check voltage, let it sit overnight, and test in the morning. if the voltage seems similar, reconnect and let it run the headlamps for 60 seconds. Bad cell? you'll see the voltage close to or below 12.

 

[brianl703]

Originally Posted By: JHZR2

Any idea what this means? Weird that the ECU would be energizing such that the scangauge would be turning on. I disconnected the charger obviously. But any ideas????


The Scangauge automatically powers up when the supply voltage increases above a certain amount. I have observed this behavior on mine. It has nothing to do with the ECU.

 

[GMBoy]

Originally Posted By: JHZR2
Originally Posted By: Quest
undo the battery terminal post and then charge the battery with a slow AC charger. When done, load-test with a carbon pile tester to verify the status of your battery.

If the battery is good, then suspect something to do with parasitic current draw somewhere in your car's electrical system.

Q.


Thing is, the battery is a side terminal type, and IIRC you arent supposed to use steel posts to test a battery. What to do??? Can one get lead screw in lugs?



Lead screw in lugs came with my OTC battery tester so they are available somewhere. But, really - you can use steel, even a proper threaded bolt. The battery cable connectors are steel.

 

[JHZR2]

Originally Posted By: brianl703
Originally Posted By: JHZR2

Any idea what this means? Weird that the ECU would be energizing such that the scangauge would be turning on. I disconnected the charger obviously. But any ideas????


The Scangauge automatically powers up when the supply voltage increases above a certain amount. I have observed this behavior on mine. It has nothing to do with the ECU.


I have a scangauge on another car that also gets battery float charged, and it doesnt have any issues like this.

Sulfated battery I think is key. Truck has sat all day, will be interesting to see where the voltage is when I get home.