Rockbox General > Rockbox General Discussion

Ipod turns suddenly off

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Ahz the Cat:
I`ve already ordered a new battery, so we will see if that helps.  I really don`t want to swap back to the ol 3G.

I am interested in this battery usage profile question...is it just that Apple os just doesn`t hit as hard when it draws on the battery?  I`m gonna fiddle around a bit more and see if I can get rockbox going even on this lame battery.  I am sure iPodLinux is gonna be a nonstarter util the power situation is cleared up....

Chronon:
BlueBarry: I agree with Febs.  Old batteries degrade in their charge capacity.  When a battery can no longer supply the necessary current it no longer acts as a voltage source.  Once the current draw depletes what the battery can produce, the voltage will rapidly drop and this will tend to flag a shutdown condition to save the battery from deep discharge.  Once the load is removed (due to shut down) the voltage between the battery terminals will return to a higher level.  This is the best explanation for what you're seeing at the moment that I can come up with.

Ahz the Cat: Probably the difference that you're seeing comes down to different decision making about when to engage safeguards to protect the battery.  If you discharge a Li+ battery too deeply it will be permanently ruined, so there's generally some failsafe that forces a device to shut down before this condition is reached.  Probably, Rockbox is a bit more paranoid than the Apple firmware.  For a healthy battery there is not much difference in runtime between Rockbox and the Apple firmware -- I believe it's even a bit more for earlier generation iPods.

Ahz the Cat:
So if RockBox senses a dangerously low battery condition it will just shut down with no warning?  Thats good to know. 

I`m not sure thats exactly what`s happening though...seems like a momentary high load condition is the cause of the shutdown, and the battery needs time to recover afterwards.   Old batteries are much less resilient than new ones, I`m assuming.

In fact, I was listening to the 5g in rockbox as I was typing this...I got 4 songs, a theme change, and a quick perusal of the database in before the thing just went dead.   This is after leaving in plugged in to the wall charger for 36 of the last 48 hours and the last 20 hours continuously. 

On my b&w 3g pod, I get better battery performance from Rockbox than with the original OS, with no funny hiccups.  Perhaps its simply that the 5g is greedier for juice regardless of firmware.

--Edit--
I was able to force the 5g to fail within the original firmware also...basically replicating the issue.  Playing a game and listening to music at the same time caused a shutdown in about 3 minutes.  Multitasking is apparently my culprit, that and a sick battery.   
--edit--
BlueBarry, if you are still having problems, try running two tasks (I played Parachutes and listened to mp3s) at the same time in your iPod`s native firmware.  If you get a rapid battery degradation similar to what you get with Rockbox, you can safely assume your battery needs replacing too. 

Chronon:
Usually, a splash screen should be displayed when a low battery condition is detected.  It's possible that instant shutdown occurs if the voltage is too low, however.  Someone with more knowledge of the source code will have to address that point.

The voltage between the battery terminals can drop very quickly if the battery cannot source enough current.  Once the circuit is opened the voltage will creep back up since current is no longer being depleted. 

Yes, aging degrades the charge capacity of Li+ batteries.

Ahz the Cat:
Well, the battery I ordered came, I slapped it in, and lo and behold, my power issues are over.
Rockbox runs great for hours on end, and I can fiddle with it all I like and no sudden shutdowns.  Occam`s Razor has once again been proven right! ;D 

Thanks for all the feedback folks...Cheers!

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