Subj:  Zaurus Power Drain Meas		Section: Sharp Zaurus
  To:  All				Monday, March 04, 1996 7:04:05 PM
From:  John Y. Chan, 76361,171		#33206

Here are the power (current) measurements that I did on Zaurus 5000 that I
think many people in this forum might 
be interested.  I saw too many questions regarding to power drain of Z5000
and the AC adapter.

Although Z use only 2 AA batteries, I think internal has a voltage step up
circuits, the current drain is not a 
constant DC current even at everything OFF state.  That could explain why the
AC adapter voltage is much higher 
than 3 volts.  It actually rated 8.5v at 300mA.  I'll be back to the adapter
in a second.

Measurements are done with fresh batteries.

OFF                ~ 0.25 mA average.
                       ~ 0.34 mA if the battery compartment switch is open
(Red Dot shown)

ON current       ~ 185 mA to 195 mA  (That is the Logo show up time and
before getting to the
	activity display).  That means if you turn your Z on and off quite often,
you will burn
	more energy.

ON current with Flash Card installed:
                       ~ 375 mA to 400 mA  (peak current is much higher).
 That explains why you may not
	be able to turn on the Z with the Flash card installed but OK without, if
your
	batteries become old.  That is also why there is no warning sign for low
battery
	with a Flash card installed and suddenly Z1 seemed to went dead.  That's
really hard to
	said it is a "Bug" as some forum members put it.

ON current with SRAM Card installed:
                      ~ 190 mA,  not much different to no card installed.  A
point for SRAM card.


	There are no addition Off standby current with either SRAM or FLASH card
installed !!


On current, Standby:
                      ~ 19.2 mA to 20 mA Avg. This is the current after the
machine turns on and you in
	one of the application.  Different application shows little difference in
current drain.

On current, Operating:
                     ~ 180 mA to 190 mA.  This is the switching current drain
from one application to
	another application.  Due to the finite time required to change from one
application to
	another or  in searching data, the more you use it, the shorter the battery
life.

Screen pressed:
	~ 150 mA to 180 mA.  That is when you use the plastic pen press on the
screen, or use
	the scroll bar or  doing drawing or what have you.  Don't put your pen
against the screen
	when you are only doing thinking.  That is a bad habit especially prone  to
while
	editing a  document.

Now AC adapter:

	With AC adapter, Off standby current drop to .07 mA.  It means that battery
drain is always
	there but it is better to leave it plug-in even not in use.

The AC adapter open circuit voltage, that mean no load voltage or just mean
when the small end plug is
	not plugged into the Z.  ~13.2 to 13.3 voltage DC.

AC adapter output voltage at Z operating  standby current. ( Z is On but no
activity.)  ~12.0 volts

AC adapter output voltage at Z operating operating current ~ 9.0 volts.

If you draw  300 mA from the AC adapter, it drops to ~8.5 volts as  the
factory labeled indicated.

Now with these data, some of the myths of the Z power drain should be clear.
 If you keep playing with it
you know the battery life can be shorten by 10 times.  Turning it on and off
with the Flash card installed
drain maximum power.  In fact, I had to shortened the test lead in order to
able to turn the darn thing on.

I cannot say the data speaks for all brand of Flash card, just the 2Meg one
that I got.  I bought 2 Z1's and
still waiting the 2nd Flash card from Sharp.

Oh, I forgot to measure the audible signal current, I turned the sound off
but it shouldn't be matter.

It should be also noted that you CAN lose TIME data if you pull the AC
adapter plug off  while
the machine is ON.  The machine will go into reset mode.  Don't press the
wrong key, it may need to
reload from you backup.  If you don't have a backup, God Bless you!


John