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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: There's a deep discharge mode and you can switch trickle charge on and
off. If you use your AJB connected to the power supply the whole time,
select "deep discharge on" and "trickle charge off". If you want to charge
your AJB over night and take it with you the next day, select "deep
discharge off" (that it starts charging immediately) and "trickle charge
on" (that the batteries remain full).
Trickle charge is needed to keep the batteries full. That's necessary
because 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).
The trickle charge time is 12 hours. It should be enough for you to
disconnect your AJB in this time and turn it off / use it. However, after
12 hours of trickle charge, it will turn it off, the batteries are
discharged and another charge cycle is started.
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 whole algorithm is made to carefully charge the batteries
full and keep them full after that with a trickle charge option. Many
documents about charge ICs were considered. If you want to know details,
then look into docs/CHARGING_ALGORITHM. If you have comments, write to
mail@uwe-freese.de or the Rockbox mailinglist.
Test results with trickle charge (battery capacities measured with an
external charger, Model "Conrad Electronic Charge Manager 2010", ~100
EUR):
- after normal charge and top off time: 1798, 1834, 1819, 1815 mAh
- after normal + top off + trickle charge (12h): 1784, 1748, 1738, 1752 mAh
- charged with external charger: 1786, 1819, 1802, 1802 mAh
You can see, whenever you take your AJB with you in the 12h trickle charge
period, the batteries are at least 97% full. :)
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 In Germany,
www.reichelt.de sells GP 2000 batteries for 2,75 EUR (12/2002).
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) and the bitrate you use (higher bitrate means
more harddisk runtime). It depends a lot on the condition of the
batteries. With 2000 mAh batteries, you should reach about 10 hours or
more. We are looking into implementing more battery-saving techniques in
rockbox to make it rock longer. If you have a modified AJB with 8 MB, you
can reach playing times of up to 16 hours with 2100 mAh batteries.
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 10V (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 10V
regulator like a 7810 of your favourite manufacturer in series.
Inside the Jukebox there is a regulator which limits the charging current
applied to the batteries. The higher the input voltage, the hotter this
IC gets. Don't use an input voltage above 12V. Using lower charging
voltage < 10V will slow down the charging. But the rockbox charging
algorithm should work then, too.
These are the output voltages of an original archos power supply:
- connected to AJB Recorder, not charging: 13,7 Volt
- connected to AJB Recorder, charging: going down to 10,4 Volt
Here is how changing the input voltage changes the charging current:
voltage charging current (limited only by the AJB)
------------------------------------------------------
7,0V 10 mA
7,5V 30 mA
8,0V 50 mA
8,5V 70 mA
9,0V 140 mA
9,5V 250 mA
10,0V 330 mA
10,5V 350 mA
11,0V 350 mA
11,5V 350 mA
12,0V 350 mA
To summarize:
- do not use an input voltage > 12V (it will only heat up the regulator)
- optimal input voltage is 10V (regulated)
- use a fuse of ~600mA
- using a different charger voids your warrenty
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, backlight off, idle 94 mA
HDD off, backlight off, play 97 mA
HDD off, backlight on, idle 129 mA
HDD off, backlight on, play 131 mA
HDD on, backlight on, play 230 mA
HD on, reading, backlight off ~ 600 mA
HD spin up before read max 800 mA
Using the power draw measurements shown above, lets look at the numbers:
Power-down and restart vs. paused for 15 minutes.:
Pause for 15 minutes will draw: 94 mA / 60 minutes * 15 minutes =
23.5 mAh.
Power-down and restart will draw about (800mA / 3600 seconds * 3
seconds = 0.6666 mAh) + (600 mA / 3600 seconds * 6 seconds = 1.0 mAh) +
(230 mA / 3600 seconds * 8 seconds = 0.5111 mAh) = 2.18 mAh total used.
Thus, leaving it paused for 15 minutes draws more power (23.5 mAh) than
turning off and then on again (2.18 mAh).
So where is the break-even point?
Each second of pause will draw about 94 mAh / 3600 seconds = 26 ľAh.
2.18 mAh / 26 ľAh = 2180 ľAh / 26 ľAh = 83.5 seconds
Thus a shutdown and restart uses as much power as 83.5 seconds of pause.
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.
Q16: When I start my Jukebox, (dis)connect the charger and browse through the
directories, the battery level changes a little bit. Sometimes it's even
going up without the charger is connected! What's wrong?
A16: Nothing's wrong. The battery level is calculated out of the voltage.
Because disk spinning, LED backlight, charger all influence the actual
battery voltage, it is usual that the battery level is going a little bit
up and down sometimes. This cannot be avoided although we tried to make
the battery level display as little confusing as we could.
Q17: My batteries are at 92%, the charger is connected to my recorder, deep
discharge is off. But charging doesn't start. What's wrong?
A17: Charging starts if the battery level is below 85%. This is because
charging batteries that *are* already more or less full is not good for
the batteries and the end of the charging cycle can't be detected safely.
So it's better to start at a level at least as low as 85%. If you want
to have full batteries in the morning, leave the charger connected over
night. Charging will then start some hours later. The second possibility:
Use the Archos charging algorithm. At least, your batteries will be full
one more time. ;-)
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