Questions Regarding Battery Charge Times.

[cuetzpalin]

Hello, I did a (quick) search but couldn't find any answer, maybe my questions are too specific. Hope somebody can help to clarify this.

Usually when you get a new product with rechargeable batteries, the manuals say that you should either fully charge the battery or wait XX hours of charging before turning on the product for the first time. Is this really necessary? I've seen the unboxing videos of the Pandora and it seems like it turns-on automatically just a few seconds after you plug it in.

Also, I'd like to know how long does it takes (approximately) to fully charge the battery when it's completely discharged.

Thanks a lot in advance, and sorry if this has been previously asked.

 

[sebt3]

Usually when you get a new product with rechargeable batteries, the manuals say that you should either fully charge the battery or wait XX hours of charging before turning on the product for the first time. Is this really necessary? I've seen the unboxing videos of the Pandora and it seems like it turns-on automatically just a few seconds after you plug it in.

As OPT test the batteries, they have to charge them
But dont expect a full charge anyway. You'll have enough to start it and know how long until you'll need to plug it
Remember that the pandora is up (have to) while charging, so you will be able to play from the very moment you'll receive it.

Also, I'd like to know how long does it takes (approximately) to fully charge the battery when it's completely discharged.

I don't know : I plug it by midnight and it's full by 6 morning.
My pandora is up full time. It's last reboot was 2 weeks ago when I borked root-FS (I had to reflash).
I use it from 6 to midnight and it's batteries aren't depleted (minimal usage : mp3 playing, but I do many others things with it every day)

 

[tsh]

Fully discharging batteries is bad for them (but our battery will protect itself from this). Telling users to fully charge the battery is a way of reducing support calls.

The wiki has some rough charge times:
http://pandorawiki.org/PowerModes
which suggest based on some short-term measurements I did that 8 hours for a full charge with the pandora in low power state, or maybe 20 if you are using it at the same time (but i think the latter is pessimistic). Any other data points can be added to the talk page.

 

[urjaman]

The default AC charger configuration regulates ~1A of power to the VBAT net (from which the pandora is also run), pandora with display at maximum brightness (default Mhz, bluetooth on (but no data), wifi off, essentially idle) is about 376-395 mA. 4200 mAh / (1000 mA - 395 mA) = 6.94214876 hours for full charge. If you turn off the display backlight it will be about 225mA, thus 5.41935484 hours for a full charge. I usually never need to go below 20% of the battery anyways (even when I carry it all around with me through the day, playing MP3 and doing other stuff).

 

[WizardStan]

Fully discharging batteries is bad for them

Caveat: the gauge that many (most? all?) lithium batteries contain tries to guess exactly how much capacity the battery can hold, and constantly adjusts its guess as you charge and discharge. After a while, if you haven't been completely discharging, it can cause the gauge to miscalculate how much the battery can actually store. Completely discharging the battery every few weeks is a good way to force that particular circuit to recalibrate. Just make sure you recharge it again shortly after discharge.

 

[Prometheus]

Every few weeks is a bit often, in my experience. Once every six months or even once a year will do the job just fine.

 

[tsh]

Fully discharging batteries is bad for them

Caveat: the gauge that many (most? all?) lithium batteries contain tries to guess exactly how much capacity the battery can hold, and constantly adjusts its guess as you charge and discharge. After a while, if you haven't been completely discharging, it can cause the gauge to miscalculate how much the battery can actually store. Completely discharging the battery every few weeks is a good way to force that particular circuit to recalibrate. Just make sure you recharge it again shortly after discharge.

This is where it starts to get tricky... Assuming that in the Pandora's case, the same fuel gauge is used for monitoring time to run remaining, and shutdown point, this procedure will possibly require you to override the automatic shutdown at 5% battery, and crash your system when the battery self-protection cuts in. My pandora was certainly pessimistic with battery life today, and i took it down to 10% reported (which does no harm at all) so I'll see what it says when it's charged again.

Occasional MOSTLY discharged should be good for the fuel gauge. Going past the auto-shutdown point is probably not recommended - the largest risk being a corrupt filesystem.