Motherboard Battery Voltage @ 4.08Volts?

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Coffee Lover

Is a motherboard/bios Battery reading of "4.08 Volts" normal, low,
high??

It reads this in BIOS screen and in various xp-based software.

thanks
 
Coffee said:
Is a motherboard/bios Battery reading of "4.08 Volts" normal, low,
high??

It reads this in BIOS screen and in various xp-based software.

thanks
Click to expand...

CR2032 is nominally a 3 volt battery. Here is a datasheet (see the
left hand side of the sheet):

http://www.panasonic.com/industrial/battery/oem/images/pdf/Panasonic_Lithium_CR2032_CR2320.pdf

If you have a multimeter, maybe you can verify the battery voltage
with that. The top of the battery is the positive terminal, and the
chassis of the computer is ground. So you shouldn't have to move
anything to get a reading. You can even do it while the computer
is running, if you're careful.

OK, I just popped open a spare computer, that I changed the CMOS
battery in a couple months ago. I touched the (+) of my meter
to the top of the battery, touched the (-) on my meter to the
shiny metal on a connector on the back of the computer, and it
reads 3.02 volts.

I cannot think of a good reason for a voltage like that to be
present. If the battery terminal really is at that voltage,
it would have exploded by now :-)

HTH,
Paul
 
I cannot think of a good reason for a voltage like that to be
present. If the battery terminal really is at that voltage,
it would have exploded by now :-)
Click to expand...

13 months old, so maybe it's 'k' , just bad bios readings.

thanks
 
13 months old, so maybe it's 'k' , just bad bios readings.

thanks
Click to expand...


You can't draw any conclusions about the battery from that
reading as it is obviously incorrect, the bios has a minor
flaw.
 
Is a motherboard/bios Battery reading of "4.08 Volts" normal, low,
high??

It reads this in BIOS screen and in various xp-based software.

thanks
Click to expand...

I just measured a fresh CR2032 lithium coin cell. It's voltage is
3.20V.

Is it possible that there is a fault on your motherboard that is
causing it to charge your battery ??? What voltage do you measure with
a multimeter? Does this voltage change when the machine is powered
down via the front switch? What about when you turn off the AC power?

FWIW, my ECS L7S7A2 motherboard uses an ITE IT8705F hardware monitor
IC. When I first power up my machine, Motherboard Monitor reports that
Vbat = 3.2V. However, after switching to standby and restarting, Vbat
drops to 2.03. Repeating this procedure causes Vbat to drop to 0V.
However the actual battery voltage, as measured by my DMM, remains at
3.2V. In my case the problem appears to be a quirk of the hardware
monitor IC.

After writing the above, I performed some tests on another box using
the same IT8705F IC. The motherboard in this case was a Soltek
SL-75DRV4. Initially the battery voltage was 3.15V, but after shutting
down and restarting, it was reported as 4.08V. When I did this again,
the reading became 2.03V. A multimeter measured 3.15V in all cases.

- Franc Zabkar
 
You can't draw any conclusions about the battery from that
reading as it is obviously incorrect, the bios has a minor
flaw.
Click to expand...

FWIW, if the hardware monitor IC has an 8-bit ADC that spans 0 -
4.096V, then a reading of 4.08V equates to 0.016V x 255 (= FFh). A
reading of 2.03V would equate to 0.016V x 127 (= 7Fh).

If the OP's machine is anything like mine, then I advise him/her to
cycle the AC power and try again.

- Franc Zabkar
 
FWIW, if the hardware monitor IC has an 8-bit ADC that spans 0 -
4.096V, then a reading of 4.08V equates to 0.016V x 255 (= FFh). A
reading of 2.03V would equate to 0.016V x 127 (= 7Fh).

If the OP's machine is anything like mine, then I advise him/her to
cycle the AC power and try again.
Click to expand...

I have just observed this same behaviour (Vbat = 4.08V) in an Acer
Aspire SA80 machine. It also uses the IT8705F hardware monitor IC.

- Franc Zabkar
 
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