Altenator voltage dropping at idle?

#1 02-21-2006, 01:53 PM

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,

oab_au · #2 02-21-2006, 03:17 PM

Quote:

Originally Posted by henryb

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

, 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.

Earthworm · #3 02-21-2006, 03:56 PM

Where are you reading the voltage from?

#4 02-21-2006, 05:44 PM

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!

oab_au · #5 02-21-2006, 05:55 PM

Quote:

Originally Posted by henryb

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.

Earthworm · #6 02-21-2006, 06:02 PM

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

NikFu S. · #7 02-24-2006, 02:25 PM

Quote:

Originally Posted by oab_au

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.

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.