2006 TSX Alternator - Testing Output

[JeffKeryk]

A year or so ago I replaced the original alternator in wifey's 2006 TSX with an O'Reilly's lifetime unit.
I don't remember whether it was new or a reman...

It put out a perfect 14.7 volts but has since dropped to low 14's. And switching on the lights drops the voltage about .2 volts.

Is this OK? Some say output of 13.7 volts or above is OK.
O'Reilly's tested the alternator on the car and declared it OK.
The battery was replaced with a Costco Interstate as well, so I doubt that is a problem.

Please offer your thoughts on this alternator.
If I pull it again, a Denso is going back in.

Thanks in advance.

 

[StevieC]

How is the health of the battery? Have you had it stress tested? It could be that it's starting to get weak. (to explain the drop since then)

Although your voltage is nothing to worry about at all in the low 14's.

 

[zfasts03]

Sounds fine. Output varies with temperature, load, battery charge, etc. Rev. the engine a little. Voltage will probably come up some.

13.8-14.8 volts is good.

Also Hondas and some other brands turn the alternator off when the battery is adequate level.

 

[Donald]

My guess (wild) is one of the diodes in the bridge is defective, probably open. A diode is a one way valve for electricity. The normal alternator is 3 phase AC and has a 6 diode bridge to convert it to DC. One diode can be open and you will get voltage but not all you should. A starter/alternator rebuild shop can put a oscilloscope on the output and tell. Individual diodes can be checked with ohm meter if one end is not connected to the circuitry.

I am told the cheap out of the country rebuilds will replace individual broken diodes. The rebuilds done locally replace the bridge if one is defective.

Measure voltage with a decent voltmeter at the battery. Forget the free HF meter.

My post may not have helped too much. Wife says I am pedantic.

 

[anndel]

13.8 V - 14.2 V for cool, mild-warm weather is good. If cold weather, 14.4 V - 14.8 V is good.

 

[JeffKeryk]

A big thanks to all who posted. I believe the battery is good, but ya never know.
I will keep an eye on it and test it again in a month.

Dunno if O'Reilly's stress tested the battery as I was not there.

Guess I just hate parts house alternators and starters.
Sheesh!

 

[Donald]

Find a local starter/alternator rebuilder.

I know one and had him rebuild Mercruiser trim pump and motor for winch on truck.

But they are a dying breed. Now they mostly do huge starters off bulldozers and similar large machines. Not many automobile starters/alternators.

 

[zzyzzx]

Your alternator is fine.

 

[JeffKeryk]

Originally Posted by zzyzzx
Your alternator is fine.


Good to know.
Cuz if I hafta pull it again I'm gonna throw it in the Pacific ocean.
Hate doing things twice... Ha!