More aggressive Recorder V1 charging (patch #1116884 from Jerry Van Baren)
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@6105 a1c6a512-1295-4272-9138-f99709370657
diff --git a/docs/CHARGING_ALGORITHM b/docs/CHARGING_ALGORITHM
index a1a6e2b..4a89cac 100755
--- a/docs/CHARGING_ALGORITHM
+++ b/docs/CHARGING_ALGORITHM
@@ -8,12 +8,13 @@
[INTRODUCTION]
-This doc describes how the charging works for the recorder. The algorithm can
-be found in firmware/powermgmt.[c|h]. Debug output is done in
- apps/debug_menu.c.
-Charging for the player and the FM/V2 recorder is done by the hardware and
-therefore isn't implemented in rockbox. Only the functions that calculate the
-battery level are also used for these models.
+This doc describes how the charging works for the recorder. The algorithm
+can be found in firmware/powermgmt.[c|h]. Debug output is done in
+apps/debug_menu.c.
+
+Charging for the player and the FM/V2 recorder is done by the hardware and
+therefore isn't implemented in rockbox. Only the functions that
+calculate the battery level are also used for these models.
All following information is related to the recorder.
@@ -38,15 +39,13 @@
[CHARGE OVERVIEW]
- If voltage drops under a certain value (with "deep discharge" option on the
- value is lower), charging is started.
+ value is a lot lower), charging is started.
- If end of charge is detected, go to top off charge.
- Make the batteries completely full. 90 minutes of top off charge (voltage
- regulation at a high value).
-- After that, do trickle charge (max. 12 hours with voltage regulation at a
- lower value).
-- When trickle charge is done and you did not disconnect or shut off your AJB
- by now, the AJB decharges normally since it reaches a low voltage and
- everything starts from the beginning.
+ regulation at a higher value).
+- After that, trickle charge (voltage regulation at a nominal battery value).
+ The trickle charge will continue as long as the charger is plugged in (this
+ is a change from the original charge algorithm).
[NORMAL CHARGE]
@@ -89,7 +88,7 @@
goes down when the temperature goes up.
NiMH batteries have a smaller delta peak than NiCd, but is is enough for
-Rockbox to detect that the batteries are full.
+Rockbox to detect that the batteries are full (in theory :-).
Related documents on the web:
@@ -114,20 +113,33 @@
So we have trickle charge in rockbox.
In simple words, rockbox charges about 15 seconds per minute in trickle mode.
-An AJB consumes 100 mA when it's on and the charging current is about 300mA.
+An AJB consumes 100 mA when it's on and the charging current is about 350mA.
So charging 15 s and decharge 45 s will keep the batteries full.
-But the number of seconds the charger is on in trickle charge mode is also
-adjusted dynamically (between 1 and 24 sec). Rockbox tries to hold the battery
-level at 5,65 V (top off charge, that means "make the batteries completely
-full") for 90 minutes, then a level of 5,45 V. If the voltage drops below the
-wanted value, rockbox will charge one second more the next minute. If is is
-greater than this value, is will charge one second less.
+But the number of seconds the charger is on in trickle charge mode is
+also adjusted dynamically. Rockbox tries to hold the battery level at
+5,65 V (top off charge, that means "make the batteries completely full")
+for 90 minutes, then a level of 5,45 V. If the voltage drops below the
+desired value, rockbox will charge one second more the next minute. If
+is is greater than this value, is will charge one second less.
-Trickle charging runs 12 hours after finishing the normal charging. That
-should be enough for charging the AJB over night and then unplug the charger
-sometime in this 12 hour trickle charge time. It is not recommended to trickle
-charge over days, that's because it is stopped after 12 hours.
+The number of seconds the charger is on in top off and trickle charge
+modes is also dependant on the charger's output voltage: if the charger
+supplies less than about 10v, the current into the batteries is less and
+thus the percentage on is increased to maintain the proper current into
+the batteries.
+
+The original recharging algorithm stopped trickle charging after 12 hours,
+at which time the battery would be discharged until the the batteries
+fell below the "start charging" level. At that time the charge cycle
+would be repeated.
+
+The time limit was removed by Jerry Van Baren (along with other changes)
+in the February, 2005 timeframe. The rationale for this is that the
+trickle charge level is very low. In addition, it is disconcerting to
+have a AJR plugged in and "recharged" only to find out that the battery
+is only 86% full. This was giving the Rockbox recharging algorithm a
+bad name and frustrating our users.
Many chargers do top off and trickle charge by feeding a constant (low)
current to the batteries. Rockbox, as described, makes a voltage regulation.
@@ -177,25 +189,23 @@
always set the battery level to 100%
- the battery level is only allowed to change 1% per minute (exception: when
usb is connected, it is allowed to go 3% down/min)
-- if charging just started (or stopped), ignore the battery voltage for the
- first 25 minutes
- after turning on the device, add another 5% to the battery level, because
the drive is used heavily when booting and the voltage usually gets a
- little higher after that
+ little higher after that (rebounds)
[WHICH CHARGING MODE TO USE]
-If you use your AJB connected to the power supply the whole time, select "deep
-discharge on" and "trickle charge off".
+Jerry Van Baren's revised recommendation: Select "deep discharge OFF"
+and "trickle charge ON". This will keep your batteries charged up and
+IMHO will not damage them.
-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).
+Original recommendation:
-A special case: If you fill up the batteries that are still nearly full every
+A special case: If you use your AJR connected to the power supply all
+the time or if you fill up the batteries that are still nearly full every
night, it is recommended that you make a complete charge cycle from time to
-time. Select "deep discharge on" and "trickle charge on" and wait till the
+time. Select "deep discharge ON" and "trickle charge OFF" and wait till the
whole cycle is over (you can speed up the discharging a little bit by turning
on the LED backlight). Even if the battery sellers say NiMH cells don't show a
memory effect, I recommend making this procedure from time to time (every 10th