Altenator voltage dropping at idle?
 

I have a '92 SVX with 260K on it and we are having a problem that I have heard other SVX owners have also experienced. I was wondering if anyone has a solution for this problem...

The altenator seems to charge just fine (14v) when the engine is running above 1000rpm's (normal driving). However, when the car is idling (700-800 rpm) the charging voltage drops down to around 11volts. If the car is left idling too long or the battery is old and it is very cold out (Canada eh)... the car will konk out.

I have talked to the dealer and they know about this problem on older SVX's even with new Subaru rebuilt altenator's. But they don't know the solution.

Has anyone ever experienced this and found a solution? Let me know.

Thanks,

I have no experience of that sort of cold:eek: , may have some effect. The 14V above 1000rpm seems normal, the 11V at idle is not. When the engine speed is below the charge speed of the alternator, the system relies on the battery, which should be 12.2V when it is not being charged. For it to be 11V either the battery has a large load no it, or it has a bad cell.

Harvey.;)

Where are you reading the voltage from?

Thanks for the quick responses guys.

First, regarding the possibility of a bad cell, it is possible, but unlikely as a month or two ago we replaced the battery. Although, it could have had a big load running on it... not sure.

The 11v could mean 11.9 volts, as it was the dealer that ran an AVR test on the altenator and the service guy said that it had less then 12 volts at idle, he didn't give me the exact number.

I would imagine during an AVR test, they don't have a huge load on the system? Not sure, never seen one run before!

Well before David says it. Get one of those volt meters that plug into the lighter socket. You can monitor the voltage on a daily bases.

Harvey.;)

Get one of those volt met... darn it! :D

Have the volt regulator checked out in the alternator. I had a similar problem, the alt would not kick in untill I hit 3000 RPM'S.

Agreed, it does sound like a voltage regulation problem. However, I did just have the alternator rebuilt less then a year ago (still under warranty from the rebuilder). Maybe I should have them check the regulator and possibly get them to replace it under warranty? Now there is a plan!

Those of you that had your voltage regulators "checked out"... what exactly was repaired? Was the standard Subaru voltage regulator replaced in the alternator? Or is there another external voltage regulator installed.

Thanks,
Brent.

It's all internal. I've had mine rebuilt twice. It's been running strong for the last 2 years without problem now.

When mine was failing the "5 warning lights" would come on and I could hear clicking coming from behind the dash. Does yours do this at all?

That's what I do.

I have this exact problem and depending on what's on or off voltage fluctuate at idle between 13 and 11v.

I made a thread about it that noone responded to.

Earthworm: No mine does not flash the warning lights at start-up, other then what it does normally. The only issue issue is that if the car is left idling for an extended period and the temperature outside is very cold and we have alot of electrical items running in the car (heater, headlights, wipers, radio, etc)... it can konk out, just by turning one more electrical item on.

No light went on in my car. I had the alt checked at two locations, all ok. Once it was installed and checked, that was a different story. The shop replaced the volt regulator and since then all has been working normal.