rockbox/docs/BATTERY-FAQ

Q1: Are my batteries charged all the time when connected to my Player/Recorder?
A1: Player: the charging is all done by hardware and the exact
    functionality is hard to determine. It is however not recommended to keep
    the charger connected for more than 10-15 hours if you're not using the
    unit.

    Recorder: no. The charging algorithm is carefully crafted in to not wear
    out the batteries any more than necessary. If you're using your unit
    connected to the charger most of the time, use the 'deep discharge' option
    to save your batteries somewhat.

Q2: Will keeping my charger connected a long time damage my batteries? Can I
    leave it over night?
A2: The charger logic lets the batteries charge until they are full. After
    that, the charger is disabled, but the device will stay powered on and
    continue to consume some power from the batteries (the hardware does
    not allow running from the charger without charging batteries, or
    powering off with the charger connected). After some time, it will
    start charging the batteries again to keep them full. This will
    wear the batteries a little, but overnight charging is what most
    people do.
    
    As the Battery FAQ at http://www.greenbatteries.com/ puts it:
    "A NiMH battery can be charged and discharged hundreds of times,
    but whether that means 200 times or 800 times has a lot to do
    with how (you use it)".

Q3: Does Rockbox charge the batteries more/less/worse/better than the Archos
    firmware?
A3: Player: Rockbox doesn't affect the charging on Players, it is all done
    by hardware logic out of software control.

    Recorder: The current release of 1.2 is much worse than the Archos
    charger, it tends to stop charging much too early and leave the batteries
    half empty.

    The current development code (CVS daily builds as of 20.8.2002) is much
    better than the 1.2 release, but still not perfect. Linus recently
    measured 6 hours continuous playtime after a rockbox charge, and much
    over 7 hours after an Archos charge. We are working on fine-tuning
    the charger logic to get the most out of the batteries, but the
    emphasis is on not overcharging them, since that would damage the
    batteries. Better be safe than sorry.

Q4: What kind of batteries are there in my factory default Player/Recorder?
A4: Both ship with 1500 mAh NiMH (Nickel Metal Hydride) batteries.

Q5: Is it hard to change the batteries? Does it void my warranty?
A5: The archos manual and web site describe how to replace the batteries,
    so you're supposed to do it. They recommend using only Archos-supplied
    batteries, but my Recorder 20 unit only shipped with one set. Some
    units have been shipped with two sets of batteries. Someone actually had
    Archos send him new batteries free of charge after they had weared out,
    under the warranty. (have asked from support-technique@archos.com,
    waiting for an answer to arrive!)

Q6: How much do replacement batteries cost? Where can I buy them?
A6: http://www.greenbatteries.com sells 1800 mAh NiMH cells at $3.25USD each,
    and I bought 4 of the same GP batteries for 20 euros in an home
    electronics & household appliance store in Finland.  NiMH batteries are
    sold in almost all shops that sell consumer electronics, and in many
    online shops. Browse around.

Q7: What kind of run-time can I expect on a set of fully-charged batteries
    when running Rockbox?
A7: For the stock 1500 mAh cells, from 6 hours to 8 hours, depending on
    which charger was used (see Q3). It depends a lot on the condition of
    the batteries. We are looking into implementing more battery-saving
    techniques in rockbox to make it rock longer.

Q8: Can I use different batteries in my Archos?
A8: Only use NiMH-type rechargeable batteries. It is considered to be safe
    to use NiMH batteries of different capacities though, a lot of people
    have purchaced 1700 or 1800 mAh batteries to replace the stock 1500 mAh
    cells and have the device run a bit longer.

Q9: Can I use non-chargeable batteries in my Archos?
A9: This is not recommended. The unit has been designed to operate with
    four 1.2V batteries producing about 4.8V at most, and using 1.5V
    alkaline/zinc carbon batteries will produce around 6.0V, which will
    heat up the unit a lot more and might even damage it. The Archos
    manual explicitly tells you not to do so.

Q10: Can I use a different charger?
A10: People have successfully used different chargers with similar
     specifications as the stock charger. The charger must have the
     same kind of connector with same polarity (center positive/+).
     The charger should supply at least 7-8 volts, and if it provides
     more than 9V, it probably should be current limited (do not
     directly plug it in your 12V car battery or it's charger!).
     
     Using lower charging voltage will slow down the charging, and using
     higher voltage will cause a higher charging current, more heat,
     and too much heat and current can damage the batteries or the unit.
     Using a different charger will void your warranty and can be
     dangerous to your unit, so we can not recommend it.
     
     Many people are happy using an external quick charger which
     is specified to work with NiMH batteries.

Q11: Can I buy a replacement charger exactly as the one Archos shipped?
A11: The FAQ on the Archos web site and the top of the charger both read:

      Output: 9VDC 600mA
      Center positive (+) polarity
      
     Chargers with similar (or user-adjustable) properties are available
     at shops selling consumer electronics.


Q12: I often need to stop my player for about 15 minutes or so, and when I do
     it runs off it's batteries.  I was wondering, which is best: shutting the
     player down completely and rebooting it when I want to listen again, or 
     leaving the unit on?  Which way does it draw more power?
A12: In our testing we found the following results:
         HDD off, LED off, idle 94 mA
         HDD off, LED off, play 97 mA
         HDD off, LED on, idle 129 mA
         HDD off, LED on, play 131 mA
         HDD on, LED on, play 230 mA
         HD on, reading, LED off ~ 600 mA
         HD spin up before read max 800 mA
    
     So leaving the unit on and paused consumes ~100mA, and thus much less
     than needing to reboot the unit.  Your mileage may vary.

Q13: When I plug the charger in my Recorder, it doesn't immediately start
     charging the batteries. And when I plug in the charger when the Recorder
     is turned off, it turns itself on and starts charging in the Archos
     software? What's up?
A13: There is a switch in the DC IN jack of the Jukebox - when a charger (or
     whatever) is plugged in, the unit is powered on, even if the charger
     is not plugged in a mains outlet.
     
     If the charger is providing power at this point, the Archos firmware
     located on the FLASH ROM does not load a new firmware version (like
     Rockbox) from the disk, but goes into charging mode instead. You can
     use this feature to get to the Archos charger if you want to.
     
     When Rockbox is running on the Recorder (the device has been booted
     without the charger) it's power management code runs once per minute
     (thus the charge level and charging status is only updated every minute).
     If the battery is not full, it will start charging. If the 'deep
     discharge' mode is enabled in the settings menu, it will start charging
     only when the battery is almost empty.