Battery issue on X5L

[anry]

Player: iAudio X5L
Rockbox version: 060925
Dual bootloader with OF (original firmware) 2.10-e

Installed Rockbox 2 weeks ago. After that charged player only once. Immediately noticed that after full charge battery meter in OF shows about 70% left. For time being I ignored that fact and kept using Rockbox. Today I notice that I can't boot into OF. When I do long power up I can see iAudio splash screen, message “Low battery” and player turns off. Though Rockbox boots up just fine and displays 10% of battery left.
Seems like Artmuzz describes similar issue in this tread http://www.iaudiophile.net/forums/showthread.php?t=10923&highlight=battery
Anyone else have similar problem?


Thanks,

Anry

[Llorean]

I don't understand what you're asking.

You've said "Rockbox boots up with 10% power left, but it's not enough to boot up the original firmware." I don't understand what exactly the problem is, other than that the original firmware requires more power to boot than Rockbox?

Also, the dual-boot feature is completely unofficial anyway.

[anry]

I saw some people complain they can’t charge their X5 after installing RockBox.
http://www.iaudiophile.net/forums/showthread.php?t=11024
http://www.iaudiophile.net/forums/showthread.php?t=9651
http://www.iaudiophile.net/forums/showthread.php?t=11363
http://www.iaudiophile.net/forums/showthread.php?t=11354
I’m trying to correlate those events.
Looking at my issue seems like RockBox can drain battery much deeper that OF – RockBox is keep running when OF refuse to boot up. According to http://www.batteryuniversity.com/partone-12.htm deep discharge will harm LiIon battery.

Extreme low voltage must also be prevented. The safety circuit is designed to cut off the current path if the battery is inadvertently discharged below 2.50V/cell. At this voltage, most circuits render the battery unserviceable and a recharge on a regular charger is not possible.

Since RockBox doesn’t have full power control on X5 yet it could be good advice do not drain battery all way down when running RockBox until full power support developed.
If it all make sense then it would be nice to put some limit into RockBox how deep it can discharge battery to protect it from damaging.

[Febs]

I read the threads you linked to.  Having done so, I'm not sure what it is that you are trying to correlate.  In one thread, as Linus noted, the battery was obviously dead as it was only giving 6 hours with the original firmware.  In another, Cowon's service department "determined that the power circuit board needs to be replaced."  Another thread consisted mostly of two people bickering about how to prolong the life of a LiIon battery, all the while agreeing that the original poster's specific problem was most likely a defective battery.

[anry]

Actually I'm just trying to find explanation for different behavior of original firmware vs RockBox in my case. When RockBox is still running and OF refuse to start. I'm also trying to understand if RockBox may cause battery deep discharge.
I would really appreciate if someone could explain how RockBox make decision when it is time to stop playing and wait for recharge.
I really love RockBox and admire all developer's work. And would like it to be the best and perfect software.

[LinusN]

Rockbox doesn't turn off when the voltage is low. It runs until the hardware shuts it off.

[pabouk]

Below is one interesting citation from the Wikipedia's Lithium ion polymer battery article.

During discharge on load, the load has to be removed as soon as the voltage drops below approximately 3.0 V per cell (used in a series combination), or else the battery will subsequently no longer accept a charge.

[xlarge]

Wich is only interesting if one knows that the x5's doesn't have smart li:ion battery hardware.

Does the OF handle all batterywatching or did Cowon purchase a battery with the logic already attached?

[anry]

I assume OF does batterywatching since it refuse to start.
Would be nice if RockBox do similar things and preserve battery from deep discharge.

[Llorean]

How many volts is your battery at when Rockbox stops functioning?

[Febs]

I assume OF does batterywatching since it refuse to start.
Would be nice if RockBox do similar things and preserve battery from deep discharge.

Again, you are assuming that Rockbox permits a deep discharge.  Have you actually observed that?  The fact that Rockbox runs until the hardware shuts the player down does not necessarily mean that the battery is subject to a deep discharge.  

[Llorean]

In fact it could very well simply mean the triggering of a circuit explicitly designed to *prevent* deep discharge.

[anry]

You are right, I haven't experience deep discharge. I just don't let RockBox to run battery all way down. To verify for sure voltage just need to be measured on the battery. I really don't want to open my X5 till warranty expires. I can only observe its behavior and drive some conclusions (or guesses) from there. May be someone with opened unit could help.
Very possible that shutdown process is triggered by circuit and not by software.