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2012 Elantra charging system questions and notes:
-Charging System is to maintain 13.5V, range from graph 11.7V to 15.3V
-If there is an alternator clutch, how does it work in respects to affecting voltage regulating?
-What part can be the culprit if not the Alternator, the regulator on the Alternator, not the battery nor battery sensor, nor any connections? Battery was tested each time at the Advance Auto Parts.

Attached is detailed summery as well as below.

2012 Hyundai Elantra charging system initial Status:
Noise coming from Alternator bearing area; audible from within the car. Belt was loosened to help minimize noise. Day 1 Sunday, Battery voltage dash light has not come on. Battery voltage measurement has not been taken. Day 3 Tuesday, Noise worsened and alternator was replaced with a refurbished one from Advance Auto Parts; Carquest brand.

Alternator replacement status:
From memory and not taking notes the initially the alternator read 14.3 volts or 13.3V upon installation and first start on Day 3 Tuesday. Within 5 miles of driving, the battery dash light lit up and the vehicle operated badly.
Day 5 Friday, part was returned and exchanged with AAP for same refurbished model. From memory, battery voltage was reading appx 12.5 volt. Upon engine start Alternator was maintaining voltage less than 13 volts. Part was returned Day 6 Saturday. Voltage drop was done on positive side and negative side with the positive side being 0 volts and the negative side having the largest drop be .002 volts.
Day 7 Sunday, 3rd refurbished alternator was obtained form Pep Boys model from Wilson Alternators. Battery Was charged overnight. Battery Voltage key off was 13.5 V. Alternator Voltage car off was 12.98V. Upon Start Battery voltage was maintained at 14.5 volts. Car turned off and ON and same reading upon start. Drove car for 2 miles and battery voltage maintained 14.5 V. at mile 2 while driving Voltage changed to 12.5V. Since then, less than 7 miles city driving, alternator maintaining voltage at 12.0 volts no load and under load voltage has been as low as 11.5 volts. Turning car off battery voltage sets to 12.0 volts.
Day 8 Monday, drove car 1 mile and within a mile noticed headlights seemed dimmer, steering was slightly stiffer; did not have voltage meter connected. At mile 3, with car in idle and minimum load, battery voltage was 9.5V. Turned car off and battery was at 11.5V. Leaving batter on trickle charge and continue trouble shooting.

443125


443126
 

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I suggest you do a voltage drop test between the following points what the problem is occurring. Battery positive post and alternator output terminal. Maximum 0.5 volts. Battery negative post and alternator housing maximum 0.2 volts. These are industry std acceptable figures. Oh and the engine must be running with the headlights on.
 

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Discussion Starter #5
I suggest you do a voltage drop test between the following points what the problem is occurring. Battery positive post and alternator output terminal. Maximum 0.5 volts. Battery negative post and alternator housing maximum 0.2 volts. These are industry std acceptable figures. Oh and the engine must be running with the headlights on.

Thanks for info guys.
Its my GF car and driving me crazy, not her.

the V drop on + was .000V and the negative was .002V.
 

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the V drop on + was .000V and the negative was .002V.
With the engine running and the headlamps switched on?
Those are not good figures for a voltage drop test. Those figures are telling you that there is no output from the alternator. If there was current flowing from the alternator to the battery there would have to be some voltage drop because there is always some resistance in the circuit. Current flow = voltage drop...It's one of the laws of physics.
 

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Ditch the junk Pepboys alternator. BTW, you found out the hard way CarQuest alternators are typically junk too.
Bit the bullet and get either an alternator from Hyundai, or whatever the OEM brand is (I don't know).
 

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.... Noise coming from Alternator bearing area; audible from within the car. Belt was loosened to help minimize noise. …
I'm not familiar with your vehicle, but it's a bit surprising to read there's adjustability in the serpentine belt loop. Most everything I'm familiar with has an automatic, non-adjustable belt tensioner in the loop. But in any case, given that you were able to loosen it, did it get adjusted back to the correct tension after the work was done?
 

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Discussion Starter #11
With the engine running and the headlamps switched on?
Those are not good figures for a voltage drop test. Those figures are telling you that there is no output from the alternator. If there was current flowing from the alternator to the battery there would have to be some voltage drop because there is always some resistance in the circuit. Current flow = voltage drop...It's one of the laws of physics.
I did both, with engine off, and engine on. Video two to make sure and review after, I did just saw a gator eat a duck in my back yard in downtown Miami lol this morning.
Initial Battery Voltage was 12.60V
Engine ON and lights on and A/C ON::
+, .001V
-,.0021V
Alternator voltage was 11.73V
Battery Voltage was 11.75
Ditch the junk Pepboys alternator. BTW, you found out the hard way CarQuest alternators are typically junk too.
Bit the bullet and get either an alternator from Hyundai, or whatever the OEM brand is (I don't know).
Well, I think so but 2 alterntors?? Improbable but not impossible. With the pepboys doing the same thing after being driven, I figure it is more likely that somehing in the car is failing and messing up the alternators or messing up the voltage regulation, maybe the ECU??

I'm not familiar with your vehicle, but it's a bit surprising to read there's adjustability in the serpentine belt loop. Most everything I'm familiar with has an automatic, non-adjustable belt tensioner in the loop. But in any case, given that you were able to loosen it, did it get adjusted back to the correct tension after the work was done?
Yes, it is adjustable. I do not have a tensioner measuring tool for the specified tension .
Charging system Start Day 8 trouble shooting.
 

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You would hear the belt slipping if the load is pulling the output voltage down to under 12 volts. As Autospark said the reading are too low if the alternator was charging at the time. You should have got something a bit higher that the reading you got on the positive side. Take the belt off and feel the alternator bearing for roughness. If diodes go they can make noises. I know your got the rolls royce of meters but is it accurate? I would think so.
 

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You would hear the belt slipping if the load is pulling the output voltage down to under 12 volts. As Autospark said the reading are too low if the alternator was charging at the time. You should have got something a bit higher that the reading you got on the positive side. Take the belt off and feel the alternator bearing for roughness. If diodes go they can make noises. I know your got the rolls royce of meters but is it accurate? I would think so.
I do not hear the belt slipping. Belt off the pulley is smooth.
Used another multimeter for the V drop test, it is more accurate but results are the same.
Vbattery car off::12.44V
dV battery neg: .009V and .015V
dV battery pos: 000V
V battery car on:9.45V and varied to 9.87V
V alternator B post to battery negative: 9.81V //V alternator : 9.85V (readings may have been swapped when wrote them down.)

Just tricked charged the battery to 12.85V
Next plan is to return the PEP boys alternator and get a NEW one from either Hyundai or Mando Alternator AMAZON
 

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I am surprised the car is still running with the battery voltage that low. It sure does look like an alternator problem but I haven't worked on an ECU controlled alternator so can't help.
 

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Video of New EOM alternator first start, SUCCESS!!

Thanks for the help guys. I did not want to claim victory with only 10 miles but I have one more question.
Any videos on how to check tightness/tension of the belt without a tool?

I was told the following checks.
-tight enough where alternator / belt can not be rotated by hand; seems to tight for me.
-tight enough to rotate the belt 90 degrees but no more than 90 at the longest section of belt from pulley to pulley

As far as the voltage on the battery.
After approximately 10 miles of driving I see the following Voltage on my OBD2 / OBD fusion app; it reads between .5 to .8 V lower than my multi-meter at the battery. Voltage Usually is held steady at 13.5V with no loads and car on. With loads and driving voltage varies from 12.5 to 13.6 but not erratically. Lesson:: Do not buy rebuilt alternators. Voltage varies due to ECU input. Want to verify proper belt tension without a tension tool.
 

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So it turned out to be the alternator. The reading difference your getting is normal due to the length of wires and the connections etc. With the belt tension (your correct) pick a long distance between 2 points (alternator/crank pulley eg) and try to twist the belt. It should be able to twist 90 degrees with a slight effort. Not gorilla effort. Less than 90 too tight more than 90 too loose.
 
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