Sansa Clip ZIP:The care and feeding of a LiPO cell - I only want the best for it

[mcc01]

Hi,

Especially cause it seems to be hard to get a replacement battery for a
Sansa Clip ZIP I really dont want to shorten its life due to the lack of
knowledge about this topic...

Here:
http://batteryuniversity.com/learn/article/how_to_charge_when_to_charge_table
I read about the best way to charge a LiPO cell.
It seems to be better to neither empty the cell completly nor to charge to 100%
every time.

But:
The cell of the Clip ZIP has a PCB attached, which stops the current to prevent
too deep discharge and overcharge.
Furthermore I dont know wether 0% and 100% of Rockbox battery already take
a security margin into account, not to load up to the 100% of what the article is
talking about -- same for the other end.

So...what is 100% and 0% of the battery meter of rockbocks in the context of prolong
the life of the cell as much as possible?

Thank you very much for any clarification of this topic!
Best regards,
mcc

[saratoga]

http://git.rockbox.org/?p=rockbox.git;a=blob;f=firmware/target/arm/as3525/sansa-clipzip/powermgmt-clipzip.c;h=5006c5834745799a64dcff2507464eaad36409ef;hb=HEAD

[mcc01]

Hi,

I always like these kinds of RTFM one-liners of an answer without any additional human
word to avoid any chance to render the answer helpful.

So,  the source code says:
 /* The battery manufacturer's website shows discharge curves down to 3.0V,
   so 'dangerous' and 'shutoff' levels of 3.4V and 3.3V should be safe.

These are voltages only...and it is still not clear, whether these are the voltages,
below or above the cell will be killed or will explode (german "Entladeendspannung"
und "obere Kniespannung" (speaking in the sense of Delta-U...if this could
be applied to LiPOs also...dont know)) or whether these voltage will garantee,
that the cell will live long enough to skip the warranty time just enough or...
whether it ensures best lifetime...that in what I am interested in.

Again: In what relationship are 100% and 0% of rockbox battery meter to
those margins mentioned in the article which I linked in my initial posting?

And: Who is the manufacturer...?

Best regards,
mcc

[saratoga]

I always like these kinds of RTFM one-liners of an answer without any additional human
word to avoid any chance to render the answer helpful.

So,  the source code says:
 /* The battery manufacturer's website shows discharge curves down to 3.0V,
   so 'dangerous' and 'shutoff' levels of 3.4V and 3.3V should be safe.

FWIW, those comments are probably referring to a different battery, since I bet that code has been copy/pasted a bunch.  I would only trust the battery voltages because they are (probably) measured.

Again: In what relationship are 100% and 0% of rockbox battery meter to
those margins mentioned in the article which I linked in my initial posting?

I think the only way you'd be able to determine this would be to get a couple dozen batteries, wear them down, and characterize their life cycle.   

[[Saint]]

Battery technology is at a point (and has been for quite a while) where a consumer doesn't need to care about this at all.

It seems odd to me to be so concerned about this when the device in question is low cost and essentially disposable.


[Saint]

[mcc01]

Battery technology is at a point (and has been for quite a while) where a consumer doesn't need to care about this at all.

...or the consumer gets the impression, that it is.
Look at the wide range of charger for example for NiMH accumulators.
Then take a look for the wide price range of those. I cannot believe
that all chargers will take care the same (good) way of your accumulators.
It is the consumer, who err. It starts with calling a accumulator a battery...

It is ok, that it seems to be odd to you.
I simply dont want to waste things.

Best regards,
mcc

[saratoga]

Battery technology is at a point (and has been for quite a while) where a consumer doesn't need to care about this at all.

...or the consumer gets the impression, that it is.
Look at the wide range of charger for example for NiMH accumulators.

This is a lithium ion battery, not NiMH.  They are very different chemistries. 

I simply dont want to waste things.

Other than time?

[steak]

I simply dont want to waste things.

So do I 

Without going into technical stuff, my advice is :

1- DO Full charge when rockbox battery meter is about to reach 30~20%.
2- DON'T charge when  rockbox battery meter is over 80%.

So for instance if the meter is at 50%...
... and you will be able to full charge when ever necessary, don't charge.
... and you won't be able to recharge even when desperately wanting to listen to music while hiking or whatever, charge.

If you have several players and don't use some for a long time :
Make sure to turn them on from time to time, check the meter and full charge if needed.

That's what I do with a couple of Sansa Clip & a couple of Cowon D2.
> My D2's are 5~8 years old and battery life is still ok (meaning no idea how long they last but based on brand new 50hrs expected, that helps)
> I have the feeling the Sansas are getting a bit short but still not to a point where I have to recharge all the time

[[Saint]]

While the advice given here isn't /bad/, battery chemistry and construction has been at a stage where users haven't needed to care about this for years.

Batteries degrade over time with use, it happens, its unavoidable.

But for a long time now consumers have been able to entrust the charging circuitry of <device> to look after the battery itself, and make a damn fine job of it.

Really, the only advice I would offer is "Don't leave it plugged in, charging, for weeks on end if you're not actually using it" - other than that, just do as you please. If you're near a charger, and its convenient to charge...do so.


[Saint]