[bookcourier] Re: Sapping batteries - a helpful warning
- From: "Greg Epley" <gregepley@xxxxxxxxxx>
- To: <bookcourier@xxxxxxxxxxxxx>
- Date: Mon, 6 Jun 2005 12:23:44 -0500
Nor was my original post intended as a technical discussion. I will forgo
offering any helpful advice here in the future. There's always someone like
you ready to destroy any other opinions. I never said I was an electronics
expert. I've never had trouble testing batteries this way, and will
continue to do so. Just because you worked with electronics doesn't mean
you understand all the nuances of every circuit in every device.
-Greg
----- Original Message -----
From: "Darren Brewer" <darren.m.brewer@xxxxxxxxxxxxxxxx>
To: <bookcourier@xxxxxxxxxxxxx>
Sent: Monday, June 06, 2005 10:39 AM
Subject: [bookcourier] Re: Sapping batteries - a helpful warning
> Hi
>
> I don't want to get into a technical discussion about loads on batteries
> etc
> as it's quite boring for most people. But I will try and justify what my
> last post was about. I did work as an electronics designer and would like
> to
> think I know about loading on power sources.
>
> Loading basically means something is connected to a power source. The
> amount
> of current drawn will vary depending on the resistance or impedance
> (resistance to AC ) of the load.
>
> Most digital multi meters have an input impedance of around 10 mega ohms
> which means that micro amps are drawn when the battery is measured. This
> means there is virtually no load on the battery. However coil multi meters
> which use switched resistors to measure a range of voltages do have much
> lower resistance's and hence do draw more current. The digital meter will
> give you a more accurate reading as it's loading is usually less. But
> neither of these meters will tell you the power of the battery only it's
> voltage at the time of measurement.
>
> However in a circuit tens or even hundreds of milli amps can be drawn
> which
> will reduce the voltage on a battery that is on it's way out.
>
> You may think the courier is not using any battery power when not in use.
> But it does. It's whats called quiescent current. Or standby current or
> standby mode. Take your pick.
>
> Agreed its not enough to significantly lower the battery voltage but if
> you
> were to play an mp3 which requires most power and measure the voltage on
> the
> battery you may find it's quite different from when the battery is not in
> the unit.
>
> Right I think thats enough of that. I think I'm a bit drained now :)
>
> Darren.
>
> ----- Original Message -----
> From: "Greg Epley" <gregepley@xxxxxxxxxx>
> To: <bookcourier@xxxxxxxxxxxxx>
> Sent: Monday, June 06, 2005 2:19 AM
> Subject: [bookcourier] Re: Sapping batteries - a helpful warning
>
>
>> Hello,
>> I've had no issues of the kind you mention testing batteries outside
>> devices in order to get an idea of how much life I could expect out of
>> them. I will continue to test them the way I believe is best, and anyone
>> who wants to follow your advice and test batteries inside equipment is
>> welcome to do so. Unless a device is actually running when such a test is
>> made, there is no "load" on the batteries. Meters may have changed over
>> the years, as has battery technology, but I've had enough people with far
>> more electronics and electrical knowledge than I likely ever will have
>> tell me that the meter is "loading" the battery when I check it. Again,
>> as I said, you continue testing your batteries your way, and I'll
>> continue
>> my way, and everyone else can do whatever they want to test their
>> batteries.
>> -Greg
>>
>> ----- Original Message -----
>> From: "Darren Brewer" <darren.m.brewer@xxxxxxxxxxxxxxxx>
>> To: <bookcourier@xxxxxxxxxxxxx>
>> Sent: Sunday, June 05, 2005 9:52 AM
>> Subject: [bookcourier] Re: Sapping batteries - a helpful warning
>>
>>
>>> 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
>>>
>>>
>>>
>>>
>>>
>>> =0AThis Message has been scanned for viruses by McAfee Groupshield.
>>>
>>>
>>>
>>>
>>>
>>>
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