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Battery measurements at power on, V2 Recorder

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dreamlayers:
When I first turn on my Archos V2 Recorder the battery gauge is much lower than the eventual place it settles on.  If I haven't turned it on in a day or so this is especially noticeable and the gauge can be over 50% lower.  (This is not discharge while off because the gauge then climbs back.)

Seeing a low gauge value for a short while isn't a big problem.  However, the low value can lead to a "low battery" shutdown.  (I mean an orderly shutdown starting with a notification saying the battery is low and I should charge.)  Earlier I had such a shutdown, then turned the device back on and eventually the battery indicator climbed to about 60%.  

Is this a bug or a hardware fault?  The battery is old and I know that lithium ion batteries develop increased internal resistance as they age.  I also know the battery contacts get dirty, although I cleaned them a few weeks ago.

dreamlayers:
It's gotten cold out recently.  The V2 Recorder was fully charged and I left it in temperatures around or just below freezing (0C) overnight.  In the morning it shut off immediately due to "low battery" after turning on.  If I plugged it in to charge, it didn't appear to charge (no animation on the charger icon), probably because the battery was full.  Then there's the charging bug which means that Rockbox shuts down due to low battery if turned on from the charging screen.   I managed to turn it on after leaving it plugged in for a bit and trying it a few times.

Should we just remove low battery shutdown on the V2 recorder?  It would fix the charging screen bug and these false low battery shutdowns when the device is cold and/or first starting up.  I hope there's still hardware which cuts off power before the battery can be damaged by power off.  I wonder how much damage can happen to the filesystem and stored data if power is cut while writing.  I suppose any damage to the filesystem would be to the file being written to, and it could be fixed by chkdsk.  Losing all settings would be bad, and in some cases losing the current recording could be very bad.

Any ideas for a better way to do battery voltage measurement?  Perhaps battery voltage measurement should only start after the hard drive has spun down the first time?  My Gmini 220 seems to do it that way.

Does anyone care about V2 recorders?

Chronon:
Was the battery still cold when you tried to turn it on?  Warming it up to room temperature would seem like a wise decision after having everything so cold.  Batteries don't really function properly with cold temperatures.  The rule of thumb that I remember from chemistry is that every 10 degree (C) decrease in temperature corresponds to a halving of chemical reaction rates.  I could imagine that having the battery too cold would compromise the battery's ability to source current, resulting in a drop in voltage when attached to a load.  If you tried to charge it in this state you probably wouldn't get very far since the battery might already be in a high energy state, chemically (i.e. maybe it was fully charged but simply incapable of discharging quickly enough to act as a voltage source).  I'm really just guessing at this, but it seems like a plausible scenario especially when coupled with the behavior you described in the previous post.  (By the way, please use the Modify button in the future.)

I don't have any comments regarding removal of low battery shutdown.  

dreamlayers:
Soon after my last post here I hacked bleeding-0711???  to remove low battery shutdown and flashed a RomBox version of that.  It has certainly helped me avoid some pointless low battery shutdowns and I don't see any ill effects.  

When the device is really cold (like -15 C) the battery simply cannot provide enough power and the device cannot finish powering up.   However, at temperatures around 0 C or with a half-full battery at room temperature the removal of low battery shutdown was very helpful.

I notice that if the battery level is detected as critical and I shut down normally I get the low battery shutdown popup instead of the normal shutting down popup.  It seems like this causes settings to not be saved.  I guess this is a good thing because it decreases the risk of messing up the filesystem.

Youb:
Hello there,

First, I'm new to the forum, and I must say that Rockbox rocks! (somebody must have said that before me...)

I am experiencing the exact same problem as you with my FM recorder. I'm using Rockbox 3.0.1 (installed by copying the files on the hard drive). From what I understood I would need to compile a custom Rockbox to tweak my Rockbox the same way you did. I guess I would be able to compile it myself if I take some time... But I'd like to ask you a few questions before...

First, you said you flashed a RomBox, if I remeber what I read some time ago, this is flashing Rockbox instead of just putting it on the hard drive right?

Second, is there an option to turn off low batt mode within the configuration files ? I've spotted "Announce Battery Level" in the manual, but I guess this is a voice option...

Last question... would an already-compiled version with no low battery shutdown be available somewhere? I am a bit lazy I know...   :D

Thanks...

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