Rockbox Technical Forums
Rockbox General => Rockbox General Discussion => Topic started by: dreamlayers on August 28, 2007, 12:11:39 AM
-
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.
-
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 (http://www.rockbox.org/tracker/task/7631) 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?
-
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.
-
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.
-
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...
-
Hello there,
First, I'm new to the forum, and I must say that Rockbox rocks! (somebody must have said that before me...)
Hi, and welcome to the forum!
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?
With RomBox code runs from ROM and constant data is only in ROM. This leaves more memory free for storing MP3 data, so the hard disk needs to spin up less often. It also speeds up startup because the Rockbox doesn't need to be loaded from disk or decompressed. The main downside is that current versions of Rockbox cannot fit in ROM, and features need to be disabled. For more information see wiki page (http://www.rockbox.org/twiki/bin/view/Main/RomBox). When I compiled Rockbox 3.0, disabling the database wasn't enough and I also had to disable the FM tuner hardware.
Rockbox can also be flashed in compressed format. The decompression is quite fast, but no RAM is saved.
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...
There is no configuration option. There is a compile-time option however: define NO_LOW_BATTERY_SHUTDOWN (see firmware/powermgmt.c (http://svn.rockbox.org/viewvc.cgi/trunk/firmware/powermgmt.c?view=markup))
Last question... would an already-compiled version with no low battery shutdown be available somewhere? I am a bit lazy I know... :D
Thanks...
I'm not aware of any already distributed build. Here's what I'm currently using on my V2 recorder (http://drop.io/dreamlayers/asset/rockboxnov07recorderv2dreamlayersbatterybuild02dec08). It's an older version, from November 2007, because that gives me more buffer space. To get more buffer space I've also removed language and codepage changing, the voice interface and radio support. The database has been removed to allow for RomBox. I could rebuild enabling FM if you want.
-
Thank you very much sir!
I am going to read about flashing RomBox properly, and give this a try. I don't think I'll ever use FM tuner, or database, so it seems to be the perfect solution.
I'll let you know. Cheers.
-
Hi,
I have been trying to flash my player.
Before doing ssomething stupid I prefer asking you...
I managed to back up my ROM on my computer (easy :)).
I have put the content of your zip file to my Jukebox, and I managed to start your Rockbox using ROLO.
Now if I replace the ajbrec.ajz file and the .rockbox folder I had with yours, my Jukebox boots up with the Archos firmware.
From what I understood to flash the Jukebox I need to first play your ajbrec.ajz file, and then play the rombox.ucl file in the .rockbox folder, right?
Now I'm a bit afraid of doing it because the Jukebox loads the Archos firmware with your files. Is it normal? I might do something wrong.
Thanks in advance...
-
You'd first need to install BootBox (http://www.rockbox.org/twiki/bin/view/Main/BootBox) so you have enough space for RomBox. This removes the Archos firmware. I recommend doing it from an official build like Rockbox 3.0.1 because some risk is involved.
Regarding ajbrec.ajz not loading, I remember the Jukebox 6000 had some bug which caused the firmware upgrade file to not load. This (http://www.rockbox.org/twiki/bin/view/Main/ArchosFAQ#I_installed_Rockbox_on_my_Archos) from the FAQ seems relevant. But since it's simple, I might as well re-build what I have for the FM recorder... here (http://drop.io/dreamlayers/asset/rockboxnov07fmrecorderdreamlayersbuild08dec08).
Flashing RomBox shouldn't involve any risk because BootBox allows you to load ajbrec.ajz or enter USB mode. Loading ajbrec.ajz is simple, just hold F1 (the top-left button) and then hold on to turn on the device. Entering USB mode seems to require holding F1, plugging in USB, and then when "Rescue boot" appears continually pressing F1 until "USB mode" appears.
Edit: I just found that if the device is idle, the battery can discharge below 2V, so:
WARNING: This build disables low battery shutdown. If the device is left on but not playing, it may be possible to overdischarge the battery. According to various sources, overdischarge damages lithium-ion batteries. Also, recovery from that state may require charging the battery externally or jump-starting the device. Under normal use, the device will shut down when the hard drive is used before the battery is overdischarged, and if not playing, idle shutoff will shut it down.
-
Awesome !
I've followed the instructions, and now, my player boots up in no time, and I can boot it up with like 5% battery left, versus 65% left before the upgrade.
Thanks a lot !
-
Recently I noticed that the LCD dimmed a lot when spinning up the hard drive and the initial battery reading at power-on was always flashing low. If I tried charging, the reported voltage would quickly exceed 4.2V and the charging current was low, as if the battery was almost fully charged. I knew it was possible the battery needed to be replaced, but before I did that I wanted to try some things.
First I discharged the battery. For a long time I was using it in the car, where typically the maximum discharge is paused state for the idle shutdown duration. I know everyone says that lithium ion batteries don't have memory, and maybe not believing them was unreasonable, but I wanted to try anyways. I left the Recorder on and stopped with backlight on, and then when the battery icon started flashing, with backlight off. By the end of the day it was still on. I wanted to leave it on until it shut off, but then I went into the battery debug screen and saw the voltage was under 2V, which is too low for lithium ion. It was my understanding that lithium ion batteries or devices using them had to have protection circuits to avoid this, and this may mean the V2/FM recorder has no such circuit. This is why I posted those warnings regarding overdischarge.
Then I started to charge via USB. This led to a few hours of charging at full current (external voltage in the battery debug screen approaching 7.0V, which I think is mislabelled and means 700mA input current). Then charging became annoyingly noisy. I noticed the reported voltage was around 4.2V and the current was dropping. I also noticed that it was dependent on orientation, and that squeezing the top rubber bumpers boosted it. That meant it was time to clean the battery contacts again.
After cleaning the battery contacts, power-on battery state was about 70% when fully charged. Also, there was no visible dimming of the LCD due to hard drive activity.