Selective battery charge on Sansa AMS, to prolong overall battery life?

[oid_maps]

is it possible on Sansa AMS devices to not automatically charge when plugged into USB?

Reason:
LiIon-batteries age by charging cycles. Also partly charging counts (almost) as a charging cycle. So, to prolong the life of the battery, it makes sense to only charge when the battery is almost empty.

So, it would be nice to have a setting that, when plugged to power, the player asks if it should charge or not, and only charge if you confirm with "yes". (This question beein enabled/ disabled by the system settings menu, for users who don't want to be bothered).
And, more advanced feature: Like on Lenovo thinkpads, to configure battery levels when to start charge and when to stop charge.

So that you do not needlessly age the battery when just quickly connecting to USB to transfer data, try out patched firmware, ...

Bye,
Oid.

[saratoga]

is it possible on Sansa AMS devices to not automatically charge when plugged into USB?

I don't think so.

Reason:
LiIon-batteries age by charging cycles. Also partly charging counts (almost) as a charging cycle. So, to prolong the life of the battery, it makes sense to only charge when the battery is almost empty.

No, this is backwards.  Frequent shallow cycles are much less damaging than less frequent deep cycles.

[Mihail Zenkov]

Reason:
LiIon-batteries age by charging cycles. Also partly charging counts (almost) as a charging cycle. So, to prolong the life of the battery, it makes sense to only charge when the battery is almost empty.

As you can see better charge Li-Ion whenever possible.  When the battery is full it recharged by a small current, which has a positive effect on its life.

[oid_maps]

Reason:
LiIon-batteries age by charging cycles. Also partly charging counts (almost) as a charging cycle. So, to prolong the life of the battery, it makes sense to only charge when the battery is almost empty.

As you can see better charge Li-Ion whenever possible.

Ah thanks for correcting me on that.
I was quite a couple of years ago with my information. When back then I have got information from electronics tinkering sites and battery care, it was always stated that LiIon-batteries (asides from storage, depending on charge and temperature when storing) age by charge cycles, almost independently of discharge/charge depth (if not fully discharged).

Is this (for me new) information due to misunderstanding in the old info, due to change in battery technology, or due to something else?

When the battery is full it recharged by a small current,

but that should depend on charging electronics. You could also charge an empty battery slowly. (And _maybe_ an almost full battery quickly if you are _very_ careful).


Thanks for pointing that out!

[Mihail Zenkov]

but that should depend on charging electronics. You could also charge an empty battery slowly. (And _maybe_ an almost full battery quickly if you are _very_ careful).

Yes, it depend. Slow charge have no disadvantage for Li-Ion and others battery (except SLA) but speed. Quick charge (high current) can't used on almost full battery, as we can't correctly check voltage on battery and prevent overcharging.

Sansa Zip do it in correct way - limit current (135-140mA)  when battery empty and fluently decrease current when battery almost full. IMHO most other devices with Li-Ion do charge in same way.

[oid_maps]

is it possible on Sansa AMS devices to not automatically charge when plugged into USB?

I don't think so.

Reason:
LiIon-batteries age by charging cycles. Also partly charging counts (almost) as a charging cycle. So, to prolong the life of the battery, it makes sense to only charge when the battery is almost empty.

No, this is backwards.  Frequent shallow cycles are much less damaging than less frequent deep cycles.

There is one more thing to that -- if the device is not used regularly. Since LiIon-batteries age also by just storing them, and the aging goes quicker the more energy they have stored (e.g. the more they are charged) -- that's why you should store them only half to 1/3 charged. So, if the device is used irregularly (which means most of the time it is just stored), it may prolog overall battery life if it is not fully re-charged after each usage.

Two URLs about that (quick googling):
http://www.mpoweruk.com/storage.htm
http://batteryuniversity.com/learn/article/how_to_store_batteries