seeking advice on high voltage

[newtovolvo]

Can someone offer advice on high voltage?
I have a 740 (1990) that has a code pointing me to high or
low voltage. I discovered this while trying to clear out a
code for another issue. I checked the voltage at the battery
with the engine running at idle and it was 14.4v. I believe
that is high but not by much. Tried switching the
regulator/brush pack (it was the original one that I put back
in) and it brought the voltage to 14.3v with the engine running
at idle.

I believe the battery is good as I measured 12.4v after it
"rested" for a couple of hours.

Anyone care to comment on this? I am wondering about the diode
bridge. I don't know what to expect if I have a bad diode in the
diode pack. I tried to measure ac voltage and did not get much
voltage at all, well under a volt.

thanks for the help

 

[Michael Pardee]

Can someone offer advice on high voltage?
I have a 740 (1990) that has a code pointing me to high or
low voltage. I discovered this while trying to clear out a
code for another issue. I checked the voltage at the battery
with the engine running at idle and it was 14.4v. I believe
that is high but not by much. Tried switching the
regulator/brush pack (it was the original one that I put back
in) and it brought the voltage to 14.3v with the engine running
at idle.

I believe the battery is good as I measured 12.4v after it
"rested" for a couple of hours.

Anyone care to comment on this? I am wondering about the diode
bridge. I don't know what to expect if I have a bad diode in the
diode pack. I tried to measure ac voltage and did not get much
voltage at all, well under a volt.

thanks for the help

The voltage will vary with temperature, dropping as the temperature rises.
14.3 or 14.4 is good for a cool day. Does your 740 have the temperature
sensor plate under the battery that connects to the alternator?

Mike

 

[newtovolvo]

The voltage will vary with temperature, dropping as the temperature
rises. 14.3 or 14.4 is good for a cool day. Does your 740 have the
temperature sensor plate under the battery that connects to the
alternator?

Mike

I am thinking of what other info I can pass along.....
I don't recall seeing anything under the battery when it was
changed in recent years, only a battery tray as I recall it was
plastic. I must say I was not really looking very hard, as I was
focused on changing the battery when I What size is this
sensor plate in inches? This is a 1990 car, temp sensor sounds
real sofisticated for a 90.

Air temp was around 50f maybe 60f yesterday when I made the
measurements- I guess that could be a cool day?

Does this still seem normal?

 

[Anders Wiklund]

I am thinking of what other info I can pass along.....
I don't recall seeing anything under the battery when it was
changed in recent years, only a battery tray as I recall it was
plastic. I must say I was not really looking very hard, as I was
focused on changing the battery when I What size is this
sensor plate in inches? This is a 1990 car, temp sensor sounds
real sofisticated for a 90.

My 740 -85 had a sensor under the battery.
I guess this really never worked, the connections where cut by my Volvo
shop.

A good idea is to measure the voltage for a longer period when driving the
car.
Voltage on my cars goes down to 13,7 or so after a while. I have made a
cable set for the ciglighter connection and for a multimeter in the other
end.

/aw (SE)

 

[Michael Pardee]

I am thinking of what other info I can pass along.....
I don't recall seeing anything under the battery when it was
changed in recent years, only a battery tray as I recall it was
plastic. I must say I was not really looking very hard, as I was
focused on changing the battery when I What size is this
sensor plate in inches? This is a 1990 car, temp sensor sounds
real sofisticated for a 90.

Air temp was around 50f maybe 60f yesterday when I made the
measurements- I guess that could be a cool day?

Does this still seem normal?

The one I have (85 760T) is the full size of the battery tray and has a
cable coming out the back that plugs right into the alternator. If you
didn't see that, yours must not have one.

The voltage sounds about right for the temperature.

Mike