Not sure what would do this but my alternator charges the battery at 14+ volts as shown on the gauge during a cold start, however after driving the car for a while voltage seems to drop to 12.5ish volts, and goes up to 13.5 if I cruise for a few minutes.

I had a problem on a previous twin turbo Z06 where alternator voltage dropped when the engine heated up, does this make any sense?

The only additional things running on the alt are the TVS water pump (if im not mistaken) and the boost a pump.

is this unusual?

 

If this is annoying you and pissing off add on electrical devices like it did in my truck you can unplug the amp load sensor located on the negative battery cable beside the battery under the hood.

This was aggravating my sub amps and was solved once I performed the above mod. It's been two weeks and everything works perfectly and the alternator holds 13.5-15.5 rock solid even with the beat cranked up.

 

Thanks for the reply, now it will annoy me if its unusual but if its a rather common thing then ill just forget about it altogether or possibly upgrade the alt without being in a hurry.

 

It's normal operation once the bcm determines you are cruising it enters gas mileage mode and shuts down the alternator for better CAFE fuel economy.

A aftermarket alternator will function the same way if it is PCM controlled like the OE unit until the ampload sensor is unplugged.

 

Is this for a silvy. I have a 2002 and would like to do this if possible.

 

2005 up have it. The pcm controls the alternator within a normal range on the 02's

 

This is nice to know... I'm going to have the look the fix up. Can you provide a link. I have Viair compressor, and I think it's my evil, and maybe the mod would help.

 

Open hood find the module on negative cable unplug connector DONE. 3- second mod no need for write up. It takes longer to open the hood than unplug the connector.

 

Thank you Sir. I appreciate it.

 

10-4