Sansa Fuze Battery Power: Differing Percentages Indicated

Hi all – I recently noticed that the percentage of remaining battery power indicated on my Sansa Fuzes – I have a 2GB and an 8GB – differs from the percentage of remaining battery power indicated via my computer when the device is plugged into my PC’s USB port.

E. g.:  Checking my “System Settings > Info” display on the Fuze, I see 27% remaining battery life.  I immediately plug the Fuze into a USB port (my computer has two; either one).  The “Properties” indicator for the Fuze’s remaining battery life is 63%. 

This is continual and repeatable.  There’s always a HUGE disparity between the percentage shown on the Fuze itself and the percentage shown via USB/PC connection.  Note that the Fuzes always indicate a much lower figure.

Any idea why this is happening?  Thanks much in advance for any replies!

Its pretty difficult to read the battery charge while its actually charging. I wouldn’t expect it to be very accurate.

Thanks for your reply.  Have you verified this yourself, though?  (Anyone?)

I understand that the “Properties” display (while the Fuze is charging) might be inaccurate.  But HUGELY inaccurate?  Thirty or forty percentage points difference?

The reason I ask is because I cannot check the Fuze’s own “Info” during charging, so I have to rely on what the PC is telling me.  I prefer to follow recommended practice with such batteries (i.e., run 'em down to about 20%, then charge 'em up to around 80%).  They last much longer that way.  And, as you know, the Fuze battery is not (easily) replaced.

When I check the “Properties” display while connected/charging, it may say 97%.  So I unplug it.  Then I immediately check the Sansa’s “Info,” but that says 62%.  So back it goes into the USB port again.  It’s a pain if I can’t (even generally) rely on what the PC is telling me and have to keep plugging in, unplugging, checking, plugging in, unplugging, checking, etc.

You shouldn’t run batteries down like that, its not good for them, and there is no need to disconnect the device before its done charging. That won’t hurt it but it won’t help it either. instead its probably best to just charge them when you’re done, and then disconnect it when your’e ready to use it. As for charging, during the constant voltage phase of the charging process, its quite difficult to gauge the actual charge without disconnecting the charger to read out the open circuit voltage. Instead of that, usually whats done is that the device will use an approximate table based on either the charge time or the voltage drop which will gradually become incorrect as the battery ages.

I don’t run them down.  As I mentioned, I recharge them when I see that they’re around 20%.  As JK98 mentioned in the “Fuze Battery Life and Good Battery Practices” thread here:  “The battery prefers a partial rather than a full discharge. Frequent full discharges should be avoided when possible.”

Thanks for the additional info.

@cyndi wrote:

I don’t run them down.  As I mentioned, I recharge them when I see that they’re around 20%.   As JK98 mentioned in the “Fuze Battery Life and Good Battery Practices” thread here:  “The battery prefers a partial rather than a full discharge. Frequent full discharges should be avoided when possible.”
 

If you’re letting it get down to 20%, that is pretty much fully discharged. The Fuze’s circuitry will shut itself down right around this level to prevent any permanent damage to the battery or charging circuitry. Letting it get down this low once in a while is OK, but I wouldn’t make a habit of it. Better to charge it when it gets down to 50% or so. These type of batteries prefer to be topped off frequently, as opposed to the older style batteries that worked best when deep-cycled.