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I'm having a problem with the charging system.

(2003 Hyundai Sonata)
in Cape May, NJ on October 06, 2013
The car was working fine until a couple weeks ago. Was on my way home from a day of driving and I noticed the clock display was dimming. I turned everything off and the car got me home, but I basically had no battery left... no lights, no signals, nothing. The battery is working fine, the Alternator is working fine, and the CPU was pulled and tested and is working fine with no faults. One mechanic has already spent 2 hours checking all the wiring and can't find a problem. What is wrong with my car???
Displaying 8 answers & 17 comments
Popular Answer
on April 10, 2014
Did you ever find the problem? I am having exactly the same problem with my 2003 Hyundai Sonata 2.4L.I replaced all belts, alternator and a new battery. While driving, first the radio cuts off, then when you turn the ac on, the fan starts blowing slower and slower and lights dim. Did you find an answer?
on April 10, 2014
The only thing I could ever come up with was that the alternator belt was slipping. I didn't have the charging problem after changing that belt.
on October 21, 2013
I had the smae problem this month on my 2003 Hyundai Sonota,2.7. Put 3 Alt.'s in until I found a good one. My problem would happen at speeds over 50. It seems the parts house I bought them from had a bad diode and would check good until at speed. Changed brands and works just fine now. Went with a factory model. Exspensive!!!!!!!
of Greg's Orange Auto on October 07, 2013
on October 07, 2013
yes it is... the alternator is working perfectly
on October 07, 2013
on October 07, 2013
Well, the battery isn't charging, so maybe I'm saying it wrong, but I'm having a problem with the way the charging system is functioning... is that a more accurate way to say it??? I don't see how the shouting is helping, or why you would be getting worked up. The battery is draining while the car is running, not while it sits, and it shouldn't be. I'm being told its more likely a short and not a parasitic drain. Does that sound right? Is there a good way to test for shorts in the system?
on October 07, 2013
Find yourself a qualified mechanic to check this out. That's all i know you can do. This should not be a problem for a mechanic that can check it out hands on. I have ask and so has another tech. how much voltage the alt. is putting out at the battery. Maybe you should find that out!
Again good luck with this, i hope you get it fixed!
on October 07, 2013
I can't answer the question cause I wasn't the one testing it! I suppose I can go back to one of the 3 mechanics who all tested the alternator and ask what the numbers were for you, if you think it would make any difference at all. I can tell you the first test was at the parts place. We took the alternator out thinking it wasn't working, and they put it on their machine and ran the test 3 times and it tested fine. I didn't look at the readout so I do not have the numbers for you. Then I took it to a garage where they tested it in the car and again the alternator was working!! The mechanic suspected a short but couldn't find anything, so he figured it was the computer. So I had the computer pulled out and tested and it's performing fine... no faults. So, I started thinking maybe its the alternator after all... maybe it's failing and is working sometimes and not other times. So I bought a new alternator and put that in the car. SAME PROBLEM!!!! THE BATTERY IS NOT CHARGING WHILE THE CAR IS RUNNING!!!!!!!!! THE BATTERY IS NOT DRAINING OVER NIGHT WHEN THE CAR IS OFF!!!!!!!! THE BATTERY IS HOLDING ITS CHARGE AND WHEN I RUN THE CAR THE BATTERY IS DRAINING!!!!!!! OR, TO SAY IT ANOTHER WAY SO IT'S ABSOLUTELY CORRECT, SOMETHING IS USING MORE ENERGY THAN THE ALTERNATOR CAN MAKE AND THERE ISN'T ANY LEFT TO CHARGE THE BATTERY!!!!!!!!!!!!!!!!!!! All I was hoping for was maybe confirmation that it's probably a short and hopefully some advice about how to find where it might be. I thought perhaps somebody had this happen in their Hyundai before, or maybe there would be somebody who was good with the electrical system in this car who had some tricks that would help. MY MECHANIC IS CHARGING ME $90.00 AN HOUR AND CAN'T FIND ANYTHING WRONG AND I HAVEN'T HAD A WORKING CAR IN THREE WEEKS!!!!!!!!!!!!! Thanks a lot for yelling at me! That's just what I needed right now. You're a real peach. I just don't understand why people are so nasty anymore. Was just looking for some help. Sorry to have bothered you.
on December 18, 2013
I don't know if you got this fixed or not is been a wile but I fiund iut that some cars are having a problem with the grounds. In the factory the chassis are being painted before the grounding straps are installed this had been causing chargibg problems. Hope they helps
on March 08, 2016
I went through exactly the same problem... AND IT DROVE ME FREAKING INSANE!!. new alternators, cleaned every connection on the car, replaced 120amp fuse even though it tested good. NOTHING WORKED!! then I read this last post... The belt looked fine.... less than a year old.... I had tightened the crap out of it while testing... couldn't be the belt ...right. Went and picked up a new belt for snits and giggles. B.I.N.G.O!! Unbelievable, I put the old one back on just to see what's up. I couldn't believe my eyes the belt was spinning slower than the new one even though it was tight.... which explained the funky voltage the alternators were spitting out, as well as why they tested good at the shop.
on April 28, 2016
THANK YOU SO MUCH FOR POSTING!!! It was so frustrating trying to figure that out, especially in light of the responses I was getting from the mechanics (Like Pushrod above!!!). The worst was being made to feel like either an idiot or a lunatic for wanting to find THE solution, instead of just listening to whatever easy and expensive advice they want to give. I had been using the same mechanic for over 20 years, and I haven't been back since refusing his advice to replace my alternator. He was completely insulted that I questioned his advice at all. So, thank you again for posting. Thank you.
on October 06, 2013
Obviously nothing now, IF all those componets checked out ok!! How much voltage is the alternator putting out when tested at the battery is what we need to know! Must be an intermittent problem.
on October 06, 2013
I put a new alternator in the car. Same problem... battery is still losing power. It charges and holds a charge. But, the alternator is not charging the battery when the car is running.
on October 06, 2013
Charge light on or amp gauge low in dash? Were 'ALL' fuses tested, especially the maxi fuses? Where did the NEW alternator come from?
on October 06, 2013
No, there are no lights in the dash. The Alternator came from an auto parts store... brand new, in the box, full lifetime warranty. I think all the fuses were tested... I took it to a mechanic to check for a short. They spent 2 1/2 hours going over the wiring and checking the connections and fuses. At least that's what they said they did.
on October 06, 2013
IF it has a light instead of a gauge and the charge or battery light is not even coming on in the dash at any time, it is either a wiring, open circuit (fuse) problem or a defective alternator! One or the other. Go get the owners manual and look in the back ot it at the index, find fuses and see if/where the alt. or charge fuse is and replace it just for the heck of it.
on October 06, 2013
There is a battery light in the dash, but it's not coming on. My alternator had to be replaced 3 years ago and when that happened the battery light did come on. It isn't coming on this time, not even when the battery got so low that I didn't have headlights, turn signals or gauges.
on October 06, 2013
Never ever comes on even when the key is turned to on? See my last reply!! Let others here know how you make out, i am sure there are other folks with this same problem.
God luck with it!
on October 07, 2013
Yes, the battery light comes on at startup like normal, but doesn't stay on to indicate a problem even when the battery's charge gets critically low. I think I'm going to have to take it back to the mechanic to see if he can chase down what's draining the battery.
on January 18, 2017
This is the exact problem I had with a 2006 Sonata 2.4.
Check for a voltage drop between the alternator and the battery. On mine, I found a drop of 1.6 volts! The fix, is to replace the wiring harness, but that requires removal of the intake manifold. I used a pre-made 2 gauge battery cable with 5/16 lugs already installed (Camco 47476 from Amazon). Attach one end to the alternator and the other to the main fuse box' (under hood) front most post (6mm stud, only one large wire on it). You may have to replace the battery also if it has been in deep discharge for a long time.
This problem causes the battery to slowly go dead, faster if you drive with a lot of electrical loads on. Once repaired, I only had a voltage drop of .2 volts at 100 amps load. Charging system fully restored. Car comes with a 110 amp alternator which I measured 118 amps when I tested it.
on April 18, 2016
Ok check your crank pully or harmonic balancer and make sure the rubber is not broken on it that's the most commen problem
on August 26, 2016
We had a similar problem and after checking the alternator and battery it was the fuse between them, on first glance it did not seem as if it had blown only when popped out and cover removed could you see the break, it had blown but the wire was still overlapping so it initiallh looked fine. Dont know if this helps anyone but might stop someone having a nightmare like we did.
on April 04, 2017
Where can I find this fuse? In fuse box under hood? Do you mean the big alternator maxifuse?
on April 04, 2017
Yes, it's a 120 Amp fuse and it's next to the battery under the hood. As I mentioned in my answer check for a voltage drop between the alternator and the battery. You must have a load to test for a voltage drop. Turn on everything, fan speed on high, ac on, rear window defroster etc.. First check the voltage at the alternator "batt" stud, the check it at the battery. There should be a reading difference no more than 0.30 volts!
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