Hi everyone. I have a 1993 lexus vcv10 car in good work condition and never replace the generator before. Last week I found the battery is low (A little hard to start the engine), so I take down the battery and charged it. Then I put a voltmeter on cigarette lighter socket to monitor the voltage. I find the voltage is 13.9V when cold start, after 10 minute engine running, the voltage is 13.3V. Then I stop the engine ,wait for half hour, then restart it, the voltage is still 13.3V, the voltmeter didn't change even if I step on the accelerater. But if I park the car for several hours, the voltage is always 13.9V on start.

Should I change the generator or check something? Or can I manually adjust the voltage to 14V? Thanks.

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Latest update:

I replaced the generator and now the votage is always around 14V and everything is fine. I test the charge current, it is around 2.5A (it is only 0.5A before), is it ok?

 

Sounds more like a battery problem to me.

Either way you should have your charging system under load before replacing anything.

How old is your Battery? If your battery is more than 4 years old, you can take a chance and replace it blindly, as it's probably at the end of its life anyways.

Phil

 

Thanks very much for your reply, my battery is 2 years old. The battery seems ok after charge, now it is work fine for a week The only issue is the lower voltage when engine hot. I notice if the engine speed is under 750RPM, the voltage is lower than 12.5V at night(with all the light turning on), and I can hear noise in generator sometimes. So I think maybe the generator is too old to supply so much power for all equipment :-)

 

You should still spend a few dollars checking your charging system before spending any money on a new Alternator.

Also check the alternator belts to make sure its not loose, worn out, or slipping.

 

Thanks a lot. I asked the local 4S of lexus in China, there'e no repairman know how to checking the charging system on such an old car .I will continue monitor the voltage, seems not a big problem.

 

Now you really got problems

 

Any decent garage, even in China should be equipped to check the charging system of any car. So I'm a bit surprised by what you said.

By the way, I was in China a few months go. Amazing country. Amazing people.

Phil

 

Glad you like here In fact the 4s told me that there's nothing wrong with my car(with out any test), 13.3V is enough to charge the battery, but I mesured the current by ammeter, it shows the charge current is only 500mA when the votage is 13.3V. I think I should replace the battery first for it is 2 years old.

 

Wow, your car is excellent! I love the white lexus es300.

 

I replaced the generator and now the votage is always around 14V and everything is fine. I test the charge current, it is around 2.5A (it is only 0.5A before), is it ok?

 

I'm still not convinced that there was something wrong with your alternator, but it looks like all is ok now.

The amount of amps that an alternator puts out varies with how much is needed to keep the battery charged, as well as how much current your car uses at any one time. So the number of amps will vary from almost 0 amps to 70 amps. it's not a fixed number. What's more important is the battery voltage.


Phil