[bookcourier] Re: Sapping batteries - a helpful warning
- From: "Darren Brewer" <darren.m.brewer@xxxxxxxxxxxxxxxx>
- To: <bookcourier@xxxxxxxxxxxxx>
- Date: Sun, 5 Jun 2005 15:52:54 +0100
The thing to remember when measuring the voltage on batteries is that the
voltage level can be quite different if the battery is not actually
powering anything when measured.
When the battery voltage is measured and it is not powering anything it is
said to be off load. But when inserted into a piece of electronics and
current is being drawn the battery is then said to be loaded and the voltage
level can significantally drop.
The only accurate way to measure the voltage of a battery is to measure it
whilst it is loaded.
So for instance the courier may report the battery as being low and needing
changing. But after you take the battery ou and take a measurement. It is
then off load. The voltage may be measured at, say 1.2 volts. It may
appear that it is ok when in fact if measured whilst in the courier it could
go down to 1 volt or less.
These are not actual values I have measured I'm just giving an example of
how the voltage level can change when a battery is in use.
The battery level circuit will monitor the voltage of the batteries whilst
they are powering the courier and they will indicate when the voltage level
falls below a certain value. I don't know what this is but obviously from
what I've just said the voltage level will go up once they are removed and
off load.
Different electronic gagets will use different amounts of current and this
determines how much the voltage will drop. The more current drawn the lower
the voltage on the battery.
Darren.
----- Original Message -----
From: "George Bell" <george@xxxxxxxxxxxxxxxxxxx>
To: <bookcourier@xxxxxxxxxxxxx>
Sent: Wednesday, June 01, 2005 12:14 AM
Subject: [bookcourier] Re: Sapping batteries - a helpful warning
Hi Greg,
Your battery experience is not exclusive to the BookCourier
by any means.
Times without number I have checked discarded batteries my
wife has "thrown out" only to find they appear to have an
acceptable voltage.
However, at the end of the day, "Ohms Law" states that Volts
time Amps equals watts.
I'll spare the science here, other than to confirm what
someone earlier that it is better to go for the 2500 mAh
type batteries which are designed to provide a higher level
of power, but for lower power devices such as the BC, result
in a longer period of use.
George.
-----Original Message-----
From: bookcourier-bounce@xxxxxxxxxxxxx
[mailto:bookcourier-bounce@xxxxxxxxxxxxx] On Behalf Of Greg
Epley
Sent: 31 May 2005 20:07
To: bookcourier@xxxxxxxxxxxxx
Subject: [bookcourier] Sapping batteries - a helpful warning
Hello everyone,
In hopes of preventing anyone else from going through this
same issue, I have a helpful note to pass along. Some
preliminary explanation is necessary first, so please bear
with me.
Explanation: Years ago, I can remember frequently using AA
alkaline batteries down to around 0.8 volts before I ended
up having to toss them. This was perhaps because devices
like toys were different from today's electronic devices;
perhaps it was the motors or the fairly low power LED's many
devices used then; I'm not sure about exactly what the
difference was. Anyway, I know the GP alkalines supplied
with my BC when I got it in late March 2005 were full
capacity because they were checked on a meter; also, the BC
reported them at 100%. Around the 22nd of May 2005, the BC
finally reported the low battery warning. Not realizing
that today's devices don't seem to use all the possible
power in alkalines that they used to, I wanted to get the
max out of my alkalines. It was late at night and I was
trying to finish a certain portion of a book so I just went
through the change battery procedure and set the supposedly
dead batteries aside to check on a meter the next morning. =20
It has been my experience in the past that AA alkalines do
not recover any significant amount of power when left
overnight; that is to say they aren't 0.6 volts or something
and then by morning they are 1.2 volts, just as an example.
Perhaps alkaline battery technology has changed over the
years and it just passed me by somewhere along the way, I
don't know. Anyway, the next morning I checked the
supposedly dead batteries and they registered 1.23 volts
each. A brand new alkaline battery will generally register
1.6 volts, plus or minus .05 volts, so I consider 1.23 volts
to be sufficient energy to run a device with no moving
parts, such as the BC. Understandably that was not a very
scientifically based conclusion, but it does have a certain
amount of logical sense to it anyway, unless one is perhaps
very skilled in electronics and knows more than most
consumers. Anyway, I went through another change battery
procedure on the BC and inserted the supposedly dead
batteries;=20
the BC registered them at 42%, so I figured great, I can
get a little more use out of them. That night, I ran for
about 18 minutes before the BC said the batteries were low;
I immediately checked the batteries on the BC and it said
14%. Again, I was busy listening to something so I just
went through the change battery procedure and put the new
batteries back in and finished out my session, setting the
supposedly dead batteries aside to check in the morning.
Next morning, the supposedly dead batteries registered at
1.22 bolts. This was weird; I'd never seen batteries,
especially alkalines, recover like this on power when left
overnight. So, I figured I'd just change them again and run
them down a little further. Upon inserting the supposedly
dead batteries in the BC, it registered them at 40%. That
night, I was listening to a book when the BC suddenly said
the batteries were low; I don't know how long I'd been
listening because the whole night went downhill from there.
I quickly tried to get the BC to tell me the level, but
don't recall now what it said. I initiated the change
battery procedure, but when I inserted the fresh batteries,
the BC was dead. I couldn't get it to talk at all. I tried
a reset procedure - no change. I tried everything I could
think of for a half hour and finally went to bed. The next
morning, I checked the supposedly dead batteries and the
meter registered them at 1.1 volts. The fresh battereies in
the BC registered at 1.55 volts. I again worked for about a
half hour with no results on the BC talking; I tried
different CF cards - nothing - nothing worked. I left the
BC with no batteries or CF card for the better part of a day
and again, no change - nothing worked, it was just dead.
Springer is currently working on my BC and I'm thankful for
that. I have since learned that alkaline batteries
apparently have an effect whereby they reflect what seems to
be a good strong charge, but in actuality the level
plumments rapidly when the batteries are back in use. This
accounts for the recovery in charge level I experienced. I
wish I'd taken the time now to check the batteries as soon
as the BC said they were low, just out of pure curiosity to
see what the meter said, but I didn't. Of course, there's a
possibility the meter would still report the charge level
higher than it actually is when the batteries are in use, so
I don't know how much good it would have done to check them.
Springer also said that the BC probably went into this
"coma" (my word not theirs) because the change battery
procedure didn't complete its cycle due to the power loss of
the batteries, and while they admit some form of alternate
power some some sort would have likely prevented the
problem, of course we all know that kind of hardware
modification isn't currently on the drawing board at
Springer.
Keeping that in mind then, what I've learned from this
experience is that when your BC says the batteries are low -
initiate a change battery procedure ASAP. If you can't
change them, leave the BC off until you can - do not under
any circumstances do what I did and do anything that saps
enough charge out of the batteries to the point that the
change battery procedure could fail like this, or you'll
most likely end up with a dead BC too. I don't know what
exactly Springer does to "fix" the problem, but to me it
would be nice if there were one of those internal reset
switches activated by inserting a paper clip tip into a
small hold on the BC to do some kind of hardware reset that
didn't involve sending the BC in for a fix by Springer.
Perhaps that's something Springer will consider for a future
BC. I don't even know if such a reset would fix the
problem.
Anyway, my apologies for this very long post, but I wanted
to be thorough in trying to explain and warn other BC users
away from sapping batteries down too low.
-Greg
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