Car Alternator or Battery Issue

Mitevo7

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Jan 14, 2008
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Dear All,

I have a car with 1JZ VVTI engine having consistent battery die on me issue. Symptoms i've detected so far:

1.) Power windows auto mode not working, unless i rev the engine to 2000 rpm
2.) Power windows roll up too damn slow
3.) Idling seems very low and at the point of stalling, when the rev gets about 400 rpm, the battery light turned on
4.) Lights were dimming but it was fixed after i replaced with a new battery (2 weeks old)

The alternator was fixed a week after replacing with a new battery, by replacing the carbon brushes due to its age. The engine starts and runs fine, however the power windows are still working slow. Idling still pretty lousy, at 650 rpm at cold start, but runs fine after warmed up.

One fine day, the battery died on me again, but partly due to the car is in a garage under going cosmetic repairs, the repair guy accidentally left the car lights on overnight. The next day we jump started the car but i doubt the battery is properly charged.

So far our test results as below:

Battery voltage while engine is off: 11.8 v (mechanic commented it is low, as it should be in between 12.2 - 12.5)

Battery voltage after engine started with no accessories on (radio, lights, A/C): 13.5v (mechanic thought it looks ok)

Battery voltage with accessories on (radio, lights, A.C): 13.8v (mechanic said it looks ok)

Honestly i think the alternator still do not produce enough charge or i am just being paranoid.

What are the chances i need to replace the whole alternator unit ?

Thanks,
Ken
 

vr2turbo

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Maybe changing the carbon not good enough, other parts high resistance.
My hyundai old alternator also charging at 13.6 to 13.8v. In the morning the kick seems slow.
My VR have a new alternator installed and charging at 14.5v....lol
 

gunnerzz

2,000 RPM
Jul 3, 2014
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Melaka
Just sharing from experience...Good alternator will produce charging V above 14V with no load.

However this will depend on the idling rpm. at normal 850rpm it will produce that 14V. Below that rpm it wont.

My ol Pajero power window is having turbo mode. Its slower at idle when aircond on.if i rev a bit it will becomes normal speed.speed different is not significant but u cam notice it.

Try maintaining 1200 - 1500 rpm and use the power window, if the speed becomes normal then the power window is not getting enough juice during idle. That could be the same reason the auto mode not triggered at low rpm.
 

vr2turbo

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The wiring could have high resistance also, like my two old cars even the starter have added relay......
 

6UE5t

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Oct 8, 2010
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My Mark X when idle gives between 13.7-14.1v, mostly hovering at 14v. The battery itself (Century Ultramax) when engine off is at 12v.
My son's Swift is higher, idle can reach 14.2-14.4v and the battery itself (Bosch) at 12.2v.
 

sweelt

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Nov 6, 2016
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Penang
power windows railing checked and clean ? my wira, idle 13.6V 800-900rpm. Cold start higher rpm show 14V.
 

vr2turbo

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power windows railing checked and clean ? my wira, idle 13.6V 800-900rpm. Cold start higher rpm show 14V.
The battery max voltage output is 12.6v, since 1 cell can produce max 2.1v, but working range if not mistaken from 11.8v upwards. Most will show 12 to 12.4v. Other than voltage got to see the current too.
Alternator charging from 13.5v upwards, best should be 14v and above....
 

Mitevo7

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power windows railing checked and clean ? my wira, idle 13.6V 800-900rpm. Cold start higher rpm show 14V.
Might be got dirty a little as it sit in the garage for about 4 months. But its was working flawlessly before the battery and alternator issues.

Thanks,
Ken
 

Mitevo7

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Jan 14, 2008
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Maybe changing the carbon not good enough, other parts high resistance.
My hyundai old alternator also charging at 13.6 to 13.8v. In the morning the kick seems slow.
My VR have a new alternator installed and charging at 14.5v....lol
Now my mechanic recommended to charge the battery to its full capacity first. When revving the engine, the V seems normal to him also its putting out 13.8 with loads. We might need to adjust the idling RPM to be higher so the charge can be higher.

Thanks,
Ken
 

vr2turbo

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Now my mechanic recommended to charge the battery to its full capacity first. When revving the engine, the V seems normal to him also its putting out 13.8 with loads. We might need to adjust the idling RPM to be higher so the charge can be higher.

Thanks,
Ken
But the main charge is when you are driving not idling. If park for long time better get those mini charger hook to house AC current....
 

Mitevo7

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But the main charge is when you are driving not idling. If park for long time better get those mini charger hook to house AC current....
Now we added a voltage regulator that increases the voltage as well as regulating it. The test results are as below:

1.) Full Load with accessories on at 2000 RPM (simulate driving conditions) - 14.4 V
2.) Idling with accessories on (A/C, headlights, Radio) - 13.2 (700 rpm)
3.) Iding with every accessories off - 14.6 V

What you guys think ?

Thanks,
Ken
 

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