2001 Sephia Alternator

I have a 2001 Sephia that, I think, has a bad alternator. With a new fully charged battery I read a normal 12.5 volts. After I start the car the voltage increases to 13.7. Again, normal. If I increase the engine speed to between 1500 and 2000 RPM the voltage at the battery terminals drops back to 12.5. Not normal. If you drive the car long enough the battery will eventually be discharged.

I took it to the dealer and they said there is nothing wrong with it.

As far as I'm concerned I thing the alternator is toast. Am I on the right track or am I way off base?

Thanks,

Mike

Reply to
Michael Bromley
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13.7 is where my sephia sits all the time. Dropping down to 12.5 during cruise is not normal, your battery should normally sit around 12.6-12.8 volts with no load. Any less than that indicates a weak cell and/or discharged battery. I would verify that the B+ lead is tight at the alternator(that's the big wire) and unplug/reseat the connector for the regulator. If it is still acting up, take it back to the dealer.

Chris

Reply to
halatos2000

Thoroughly clean both battery terminals and the ground strap to the motor. Have your battery tested at an auto parts store that offers free testing (checking for a shorted or dead cell). Remove, clean and reseat the plug in your alternator (it goes to the voltage regulator). If none of this makes a difference then it sounds like your voltage regulator inside your alternator is going south - time to replace the alternator.

Cheers - Jonathan

Reply to
Jonathan Race

Thanks for the feedback, guys. I had already done the basic stuff like checking all the connectors, etc. and after that had my regular mechanic check it out. He agrees that it is probably the alternator but what is curious is why the charging indicator light on the dash doesn't come on. In fact the service manager at the dealership was trying to tell me that it couldn't be the alternator because the light wasn't on. I told him that I hoped that wasn't his primary diagnostic tool for troubleshooting charging problems. Once I finally got the chance to describe the exact symptoms they agreed to look at it again on Monday.

Mike

Reply to
Michael Bromley

Mike,

You're quite correct with that - the dashboard light is not an ultimate diagnostic for the state of the alternator. This light responds to the rotor excitation and voltage regulator, which may still be 100% OK, but if one or more of the diodes in the three phase bridge rectifier happens to go, then the DC output will drop off accordingly, and likely to a level that is insufficient to simultaneously supply the cars running requirements and charge the battery.

I recommend that you take the car to an auto-electrical service place instead of the KIA dealer, and they may replace only the bridge rectifier (which is cheap), or they may only deal in rebuild or new exchange complete alternators.

The fact that you can run for a considerable time on a fully charged battery, should indicate you have a healthy battery.

Adam.

Reply to
Peter H.M. Brooks

Mike,

You're quite correct with that - the dashboard light is not an ultimate diagnostic for the state of the alternator. This light responds to the rotor excitation and voltage regulator, which may still be 100% OK, but if one or more of the diodes in the three phase bridge rectifier happens to go, then the DC output will drop off accordingly, and likely to a level that is insufficient to simultaneously supply the cars running requirements and charge the battery.

I recommend that you take the car to an auto-electrical service place instead of the KIA dealer, and they may replace only the bridge rectifier (which is cheap), or they may only deal in rebuild or new exchange complete alternators.

The fact that you can run for a considerable time on a fully charged battery, should indicate you have a healthy battery.

Adam.

Reply to
Adam

Persistence pays. Apparently my chat with the Service Manager on Friday was worth it. I must have convinced them to test the alternator output at cruise RPM because they replaced the alternator yesterday. Since it was still under warranty there was no charge. I'm getting a pretty consistent

14.2 out of it through out a range of engine speeds even when I add load by turning on the headlights and the fan on full.

Mike

Reply to
Michael Bromley

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