docs/BATTERY-FAQ - rockbox - Gitiles

 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: It is not very hard - the Archos manual and the FAQ on their web site
     describe how to do it. Their technical support confirmed that
     replacing the batteries with NiMH cells (of different capacities)
     will not void the warranty. Just don't remove the screws.

     Some units have been shipped with two sets of batteries, my Recorder 20
     only had one set. Someone actually had Archos send him new batteries
     free of charge after they had weared out, under the warranty.

 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. There's a pretty good comparison between
     different battery makes and models at the digital imaging resource site:
     http://www.imaging-resource.com/ACCS/BATTS/BATTS.HTM

 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? How much playtime would
     I gain by using 1800 mAh batteries instead of the 1500 mAh ones?
 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. 2000 mAh batteries are
     just appearing in shops are equally good to use.

     In theory, running time = capacity of batteries / current drawn by device,
     so running time should increase linearly by the capacity, and 2000 mAh
     over 1500 mAh should give 33% longer running time. In practice, the
     mAh ratings are more or less tuned up by the marketing department
     (think of watts on the back of "hi-fi" speakers and amplifiers) and
     what you actually get out of the cells is something else than what is
     printed on them. Check the excellent imaging-resource link above for
     details!

 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.
     Also, if you connect the charger, it may even destroy both the batteries
     and the unit.

 Q10: Can I use a different charger?
 A10: The short answer is: Using a different charger will void your warranty
      and can be dangerous to your unit, so we can not recommend it.

      On the other hand, 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 10V, it probably should be regulated to 9V (do not
      directly plug it in your 12V car battery or it's charger!).
      The universal travel charger sold by Archos is specified at
      12V, 1.2A so that's probably the maximum rating you should use.
      A good circuit for powering from a car battery or other source
      with a higher voltage would be a 600 mA fuse and a 9V regulator like
      a 7809 of your favourite manufacturer in series.

      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.
      Inside the Jukebox there is a regulator which limits the charging
      voltage applied to the batteries (which in turn limits the current
      - the usual ohm's law applies: current = voltage / resistance) but
      if a high input voltage is applied, the regulator will heat up a lot!

      Many people are happy using an external quick charger which
      is specified to work with NiMH batteries. This is completely safe
      and will not void your warranty.

 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

      The universal travel charger sold separately on the Archos web site
      is specified for 12VDC, 1200mA output.

      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 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.

 Q14: When I plug the charger in my Recorder, it doesn't immediately start
      charging the batteries!
 A14: 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.

 Q15: What about the memory effect? Should I be worried about it or not?
 A15: That depends on who you ask. ;-) NiMH sellers say NiMHs are better and
      do not have a memory effect, but the usual opinion seems to be that
      they do, although it is very small.

      However, if you use your AJB connected to the charger all the time,
      we recommend you to use the deep discharge option.
	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: It is not very hard - the Archos manual and the FAQ on their web site
	describe how to do it. Their technical support confirmed that
	replacing the batteries with NiMH cells (of different capacities)
	will not void the warranty. Just don't remove the screws.

	Some units have been shipped with two sets of batteries, my Recorder 20
	only had one set. Someone actually had Archos send him new batteries
	free of charge after they had weared out, under the warranty.

	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. There's a pretty good comparison between
	different battery makes and models at the digital imaging resource site:
	http://www.imaging-resource.com/ACCS/BATTS/BATTS.HTM

	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? How much playtime would
	I gain by using 1800 mAh batteries instead of the 1500 mAh ones?
	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. 2000 mAh batteries are
	just appearing in shops are equally good to use.

	In theory, running time = capacity of batteries / current drawn by device,
	so running time should increase linearly by the capacity, and 2000 mAh
	over 1500 mAh should give 33% longer running time. In practice, the
	mAh ratings are more or less tuned up by the marketing department
	(think of watts on the back of "hi-fi" speakers and amplifiers) and
	what you actually get out of the cells is something else than what is
	printed on them. Check the excellent imaging-resource link above for
	details!

	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.
	Also, if you connect the charger, it may even destroy both the batteries
	and the unit.

	Q10: Can I use a different charger?
	A10: The short answer is: Using a different charger will void your warranty
	and can be dangerous to your unit, so we can not recommend it.

	On the other hand, 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 10V, it probably should be regulated to 9V (do not
	directly plug it in your 12V car battery or it's charger!).
	The universal travel charger sold by Archos is specified at
	12V, 1.2A so that's probably the maximum rating you should use.
	A good circuit for powering from a car battery or other source
	with a higher voltage would be a 600 mA fuse and a 9V regulator like
	a 7809 of your favourite manufacturer in series.

	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.
	Inside the Jukebox there is a regulator which limits the charging
	voltage applied to the batteries (which in turn limits the current
	- the usual ohm's law applies: current = voltage / resistance) but
	if a high input voltage is applied, the regulator will heat up a lot!

	Many people are happy using an external quick charger which
	is specified to work with NiMH batteries. This is completely safe
	and will not void your warranty.

	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

	The universal travel charger sold separately on the Archos web site
	is specified for 12VDC, 1200mA output.

	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 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.

	Q14: When I plug the charger in my Recorder, it doesn't immediately start
	charging the batteries!
	A14: 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.

	Q15: What about the memory effect? Should I be worried about it or not?
	A15: That depends on who you ask. ;-) NiMH sellers say NiMHs are better and
	do not have a memory effect, but the usual opinion seems to be that
	they do, although it is very small.

	However, if you use your AJB connected to the charger all the time,
	we recommend you to use the deep discharge option.