I know this is one of the most of basic questions for the experienced
out there, but I don't know it and I thought this would be a good quick way
to find the answer. I'm developing a few battery based applications and was
wondering on ratings. Am I correct in assuming that the standard rating is
Amp/Hours? And if so, is it just a ratio, i.e. a 1 amp/hour battery could
theoretically supply 2 amps for 30 minutes? And lastly, does anyone have a
chart on the amp/hour ratings on most popular battery types, AA, AAA, 9V,
Alkaline, Normal, Ni-Cad? Thanks in advance for any into. TTYL
Batteries are definitely _not_ a basic question, they are a basic _pain_...
Batteries are rated in amp-hours, and what the manufacturers are saying is
that they guarantee you will get less than they rate, typically about 50%.
For instance, a Duracell D-cell is rated at 18 amp-hours. At a 20-hour
rate, you'll get 9 or 10 amp-hours. At a 100-hour rate, you'll get 12
amp-hours discharging to .9 volts. At room temperature.
I left my battery literature in my cubicle, I'll fill in the blanks tomorrow.
Cheers,
Bob
At 10:46 PM 11/20/97 -0500, you wrote:
> I know this is one of the most of basic questions for the experienced
>out there, but I don't know it and I thought this would be a good quick way
>to find the answer. I'm developing a few battery based applications and was
>wondering on ratings. Am I correct in assuming that the standard rating is
>Amp/Hours? And if so, is it just a ratio, i.e. a 1 amp/hour battery could
>theoretically supply 2 amps for 30 minutes? And lastly, does anyone have a
>chart on the amp/hour ratings on most popular battery types, AA, AAA, 9V,
>Alkaline, Normal, Ni-Cad? Thanks in advance for any into. TTYL
>
> I know this is one of the most of basic questions for the experienced
>out there, but I don't know it and I thought this would be a good quick way
>to find the answer. I'm developing a few battery based applications and was
>wondering on ratings. Am I correct in assuming that the standard rating is
>Amp/Hours? And if so, is it just a ratio, i.e. a 1 amp/hour battery could
>theoretically supply 2 amps for 30 minutes? And lastly, does anyone have a
>chart on the amp/hour ratings on most popular battery types, AA, AAA, 9V,
>Alkaline, Normal, Ni-Cad? Thanks in advance for any into. TTYL
Would that it was a linear tradeoff. Most times an amp-hr rating is given,
you'll see there's some small print that says "C/20" or some such. This
means that the battery is rated to produce that number of amp-hrs when
discharged over twenty hours. Higher currents use up battery capacity
disproportionately quicker.
For example, at 25 deg C a Ni-Cd D-cell will source about 1.1 A when
discharge for one hour, or about 1.1 A-hr. This same cell will give you
about 1.4 A-hr when you discharge it over the course of five hours (C/5),
whereas a 12 minute rate gives you only 80 percent the A-hrs.
Radio Shack has a little booklet, the "Enercell Battery Guidebook"
(#62-1396) which gives you lots of discharge curves for the types of
batteries they carry. For gelled-electrolyte cells and high capacity
Ni-Cds, get the information directly from the manufacturer (there's lots of
variation).
--BN
----------------------------------------------------------------------------
Country Robot "Modular robot components
69 S. Fremont Ave. # 2 for education and industry"
Pittsburgh, PA 15202
----------------------------------------------------------------------------
> Would that it was a linear tradeoff. Most times an amp-hr rating is given,
> you'll see there's some small print that says "C/20" or some such. This
> means that the battery is rated to produce that number of amp-hrs when
> discharged over twenty hours. Higher currents use up battery capacity
> disproportionately quicker.
>
> For example, at 25 deg C a Ni-Cd D-cell will source about 1.1 A when
> discharge for one hour, or about 1.1 A-hr. This same cell will give you
> about 1.4 A-hr when you discharge it over the course of five hours (C/5),
> whereas a 12 minute rate gives you only 80 percent the A-hrs.
Good points. Look at those curves *VERY* carefully. Make sure your pack
can deliver enough in all the possible conditions. Also make sure your
application switches off properly if the voltage is too low.
Here are a few more points to consider :
Will it get very hot or cold?
Will you float it, or deep discharge it?
Will it be stored in discharged state?
What is the minimum voltage you can get away with?
What is the maximum voltage you can get away with?
Does it have to be fast charged, or can it be trickle charged?
Do you have different voltage requirements?
What will the average and (important) peak current be?
What is the maximum space/weight you can get away with?
What sort of freedom does your budget allow?
Is it a stock item (you can have multi-month lead times on batteries)?
What is the typical float life expectancy?
How many deep discharge cycles can it handle?
How profound is the memory effect (Some NiCd)?
Do you need constant I, or constant V charging circuitry?
Do you need special charge termination procedures?
This also proves that answers only create more questions! :)
--
Friendly Regards
Tjaart van der Walt spam_OUTtjaartTakeThisOuTwasp.co.za
_____________________________________________________________
| WASP International http://www.wasp.co.za/~tjaart/index.html |
| R&D Engineer : GSM peripheral services development |
| Vehicle tracking | Telemetry systems | GSM data transfer |
| Voice : +27-(0)11-622-8686 | Fax : +27-(0)11-622-8973 |
| WGS-84 : 26010.52'S 28006.19'E |
|_____________________________________________________________|
On Fri, 21 Nov 1997 07:34:00 +0200 Tjaart van der Walt
<.....tjaartKILLspam@spam@wasp.co.za> writes:
>Robert Nansel wrote:
>
>> Would that it was a linear tradeoff. Most times an amp-hr rating is
>given,
>> you'll see there's some small print that says "C/20" or some such.
>This
>> means that the battery is rated to produce that number of amp-hrs
>when
>> discharged over twenty hours. Higher currents use up battery
>capacity
>> disproportionately quicker.
>>
>> For example, at 25 deg C a Ni-Cd D-cell will source about 1.1 A when
>> discharge for one hour, or about 1.1 A-hr. This same cell will give
>you
>> about 1.4 A-hr when you discharge it over the course of five hours
>(C/5),
>> whereas a 12 minute rate gives you only 80 percent the A-hrs.
This is for the cheap consumer "D-cell" which actually is a sub-C cell
inside a larger case. A true "D" Ni-Cd, much heavier since it is all
active material, will hold about 4 A-H. The same inefficiency at high
rates presists, but now the high rates are 4 times higher as well.
Something about the chemistry of true "high capacity" Ni-Cds (such as the
950 mA-H AA cells) doesn't work well for high peak currents. The
standard capaicty or high-rate ones would be better in this case.
Manufacturers don't say much about the capacity of alkaline batteries, I
think a safe assumption would be about 4x the capacity of the same size
Ni-Cd. But not rechargeable, or rechargeable only a small number of
times. This is the least expensive battery system to manufacture, since
the user pays someone else for the batteries.
For many PIC projects that use only a few mA and are shut off most of the
time, user-replaceable primary batteries may be the best choice. Ni-Cd
batteries discharge by themselves when not in use, so the devide would
need to be recharged every few months regardless of how much it is used.
Alkaline batteries can sit idle for years without losing much energy.
>Good points. Look at those curves *VERY* carefully. Make sure your
>pack
>can deliver enough in all the possible conditions. Also make sure your
>application switches off properly if the voltage is too low.
In general, look at the curves, then install about 50% more capacity than
you think it'll need. The extra capacity will extend the useful life of
the batteries two ways: the device will still function for the rated
operating time when the batteries are old and tired, and the number
and/or depth of discharge cycles won't be as much, so the batteries won't
get old and tired as soon.
> wondering on ratings. Am I correct in assuming that the standard rating is
> Amp/Hours?
PTM: No. It's Ah, meaning A x h. Using a 1 Ah battery 2 Ampers x 1/2 hours
empies it as 1/2 Amperes x 2 hours. (Not counting the pecularities of the
chemistry)
> And if so, is it just a ratio, i.e. a 1 amp/hour battery could
> theoretically supply 2 amps for 30 minutes? And lastly, does anyone have a
> chart on the amp/hour ratings on most popular battery types, AA, AAA, 9V,
> Alkaline, Normal, Ni-Cad? Thanks in advance for any into. TTYL
PTM: In NiCd:s I use normally these aproximations: AA 500 mAh 1$, 750 mAh
1.5$, 1200 mAh 3$ 9V 100 mAh 6$ UM3 1200 mAh 3$, 4500 mAh 9$. Normal
sink+carbon and alkaline batteries are a bit cheaper and have a
bit more kick, but you can never trust that they are fresh.
--------------------------------------------------------------------------
PTM, pasi.mustalahtiKILLspamutu.fi,.....ptmustaKILLspam.....utu.fi,http://www.utu.fi/~ptmusta
Lab.ins. (mikrotuki) ATK-keskus/Mat.Luon.Tdk OH1HEK Lab.engineer (PC
support) Computer Center OI7234 Mail: Turun Yliopisto / Fysla,
Vesilinnantie 5, 20014 Pt 02-3336669, FAX 02-3335632 (Pk 02-2387010, NMT
049-555577)
--------------------------------------------------------------------------
On Fri, 21 Nov 1997, Mike Keitz wrote:
> On Fri, 21 Nov 1997 07:34:00
+0200 Tjaart van der Walt
> <EraseMEtjaartspam_OUTTakeThisOuTwasp.co.za
> writes:
> >Robert Nansel wrote:
> > In general, look at the curves, then install about 50% more capacity
> > than you think it'll need. The extra capacity will extend the
> > useful life of the batteries two ways: the device will still function
> > for the rated operating time when the batteries are old and tired, and
> > the number and/or depth of discharge cycles won't be as much, so the
> > batteries won't get old and tired as soon.
PTM: I have used 'some' series of NiCd for years in flshlights, razors,
radios, portable oskilloscopes, computers, NMT, 2m HAM, and so on. I have
decided to use those low capacity versions where ever possible. They seem
to function longer and they dont have to be loaded so carefully. A high
capacity cell might be dead after about 30 cycles with a good charger.
Some low capacity cells have lasted now about 1000 cycles in very hard
environments. The worst are these used in portable computers and NMT.
After about 50 cycles they are dead. And I mean dead. No fast hard pulse,
slow charge or water immersion can revitalise them.
Worst of all seems to be these fast chargers. Even a regular emptying of
the cells don't help. I think these rapid chargers drive the water out of
the cell.
--------------------------------------------------------------------------
PTM, pasi.mustalahtispam_OUTutu.fi,@spam@ptmustaKILLspamutu.fi,http://www.utu.fi/~ptmusta
Lab.ins. (mikrotuki) ATK-keskus/Mat.Luon.Tdk OH1HEK
Lab.engineer (PC support) Computer Center OI7234
Mail: Turun Yliopisto / Fysla, Vesilinnantie 5, 20014
Pt 02-3336669, FAX 02-3335632 (Pk 02-2387010, NMT 049-555577)
--------------------------------------------------------------------------
>Manufacturers don't say much about the capacity of alkaline batteries, I
>think a safe assumption would be about 4x the capacity of the same size
>Ni-Cd. But not rechargeable, or rechargeable only a small number of
>times. This is the least expensive battery system to manufacture, since
>the user pays someone else for the batteries.
I recently needed detailed discharge curve info on alkalines, and was
staggered to find that Duracell couldn't supply anything othr than a
couple of reference curves at specific loads & temps. Surely these
guys have been making batteries long enough to be able to supply a
simple program which would give a discharge curve at any given load &
temp (i.e. what the customer really NEEDS) - apparently not! We had to
spend a lot of time testing, as we had to provide a lo-bat warning
with a specific amount of running time available (due to the standards
the product had to comply with). Lack of info was a REAL pain.
____ ____
_/ L_/ Mike Harrison / White Wing Logic / KILLspamwwlKILLspamnetcomuk.co.uk _/ L_/
_/ W_/ Hardware & Software design / PCB Design / Consultancy _/ W_/
/_W_/ Industrial / Computer Peripherals / Hazardous Area /_W_/
At 10:46 PM 11/20/97 -0500, you wrote:
> I know this is one of the most of basic questions for the experienced
>out there, but I don't know it and I thought this would be a good quick way
>to find the answer. I'm developing a few battery based applications and was
>wondering on ratings. Am I correct in assuming that the standard rating is
>Amp/Hours? And if so, is it just a ratio, i.e. a 1 amp/hour battery could
>theoretically supply 2 amps for 30 minutes? And lastly, does anyone have a
>chart on the amp/hour ratings on most popular battery types, AA, AAA, 9V,
>Alkaline, Normal, Ni-Cad? Thanks in advance for any into. TTYL
>
>
BATTERY LIFE Load in mA
-----Type------ 0.8 8.0 80
"AA" Standard 1100 97 4
"AA" Heavy Duty 1350 120 9
"AA" Alkaline 2000 190 16
"C" Standard 2400 240 12
"C" Heavy Duty 3650 352 28
"C" Alkaline 5600 560 49
"C" Lithium 6250 625 63
"D" Standard 5600 560 21
"D" Heavy Duty 7020 702 68
"D" Alkaline 11500 1200 108
Life in hr
The idea is a battery will give 1 amp for 1 hour .5 amp for 2 hour etc.
There are some factors that mess up the ideal world. At high drain the
internal resistance causes the battery to heat up and you lose capacity. At
very low drain there is a self discharge that causes a shelf life and
messes up the results there as well. There are a lot of other factors like
temperature but the general rule of thumb is as above. The chart is typical
values and the best most accurate values would be from the manufacturer of
the batteries themselves due to changes in chemistries and cell design over
time and from company to company.
Your question may be basic - but one of the important elements of any
battery powered system. The simple answer to your question is that the
'rating' is a measure of the Amp-Hours capacity of the battery or
current x time x voltage = power. In the real world, as others I am sure
will point out, the actual capacity of a given battery type or make is
highly variable.
The more critical the application the more you will have to investigate
the battery selection. Yeah you can start with manufacturer's specs, but
in well engineered applications you'll end up knowing more about how the
battery works in your use than the apps engineer at battery company X ,Y
or Z. Many of the major battery companies are putting real spec sheets
on the Web now - so use Alta Vista or such to find their apps section.
Like:
> ----------
> From: Herbert Graf[SMTP:TakeThisOuThgrafEraseMEspam_OUTGEOCITIES.COM]
> Sent: Thursday, November 20, 1997 7:46 PM
> To: RemoveMEPICLISTTakeThisOuTMITVMA.MIT.EDU
> Subject: Batteries [OT]
>
> I know this is one of the most of basic questions for the
> experienced
> out there, but I don't know it and I thought this would be a good
> quick way
> to find the answer. I'm developing a few battery based applications
> and was
> wondering on ratings. Am I correct in assuming that the standard
> rating is
> Amp/Hours? And if so, is it just a ratio, i.e. a 1 amp/hour battery
> could
> theoretically supply 2 amps for 30 minutes? And lastly, does anyone
> have a
> chart on the amp/hour ratings on most popular battery types, AA, AAA,
> 9V,
> Alkaline, Normal, Ni-Cad? Thanks in advance for any into. TTYL
>
In message <19971121.011900.2774.3.mkeitzEraseME.....juno.com>, Mike Keitz
<EraseMEmkeitzJUNO.COM> writes
[snipped]
>Manufacturers don't say much about the capacity of alkaline batteries, I
>think a safe assumption would be about 4x the capacity of the same size
>Ni-Cd. But not rechargeable, or rechargeable only a small number of
>times. This is the least expensive battery system to manufacture, since
>the user pays someone else for the batteries.
>
>For many PIC projects that use only a few mA and are shut off most of the
>time, user-replaceable primary batteries may be the best choice. Ni-Cd
>batteries discharge by themselves when not in use, so the devide would
>need to be recharged every few months regardless of how much it is used.
>Alkaline batteries can sit idle for years without losing much energy.
A couple of years ago I plotted discharge curves for a number of
different AA size batteries feeding a small torch bulb (it seemed a
reasonable load to use!). If anyone is interested let me know, and I'll
dig the results out and stick them on my web site.
One point, Duracell batteries were the best I tried!.
In message <RemoveME19971121.011900.2774.3.mkeitzspam_OUTKILLspamjuno.com>, Mike Keitz
<RemoveMEmkeitzTakeThisOuTspamJUNO.COM> writes
[snipped]
>Manufacturers don't say much about the capacity of alkaline batteries, I
>think a safe assumption would be about 4x the capacity of the same size
>Ni-Cd. But not rechargeable, or rechargeable only a small number of
>times. This is the least expensive battery system to manufacture, since
>the user pays someone else for the batteries.
>
>For many PIC projects that use only a few mA and are shut off most of the
>time, user-replaceable primary batteries may be the best choice. Ni-Cd
>batteries discharge by themselves when not in use, so the devide would
>need to be recharged every few months regardless of how much it is used.
>Alkaline batteries can sit idle for years without losing much energy.
A couple of years ago I plotted discharge curves for a number of
different AA size batteries feeding a small torch bulb (it seemed a
reasonable load to use!). If anyone is interested let me know, and I'll
dig the results out and stick them on my web site.
One point, Duracell batteries were the best I tried!.
This months (December) Consumer reports did a study of alkaline and Ni-Cad
batteries and rated some major brands. Though not really what you may be
looking for it might be of use to people on the list.
Rob
At 10:46 PM 11/20/97 -0500, you wrote:
> I know this is one of the most of basic questions for the experienced
>out there, but I don't know it and I thought this would be a good quick way
>to find the answer. I'm developing a few battery based applications and was
>wondering on ratings. Am I correct in assuming that the standard rating is
>Amp/Hours? And if so, is it just a ratio, i.e. a 1 amp/hour battery could
>theoretically supply 2 amps for 30 minutes? And lastly, does anyone have a
>chart on the amp/hour ratings on most popular battery types, AA, AAA, 9V,
>Alkaline, Normal, Ni-Cad? Thanks in advance for any into. TTYL
>
>
Sorry I'M not Mike, but this is Piclist, and here is my advice.
If you charge your battery, measure the energy you put in.
In your system, measure the energy sucked away from the battery,
then discharge completely your battery; don't forget
to measure it's expiration energy.
Then compute the lossssss.
A perfect battery has no loss, nobody's perfect.
Watch the loss !
Here i want to cite the appropriate song for the circumstance.
"You can watch them die... Live on T.V. "
This song is from "The BOX"
Batteries are good for human beeing, given them a reasonable retiremnt
time
before they pass away.
>
> Battery performance information is extremely hard to get hold of. We
> are making a product at the moment that needs to incorporate both a
> battery charger and a mechansim for determining the amount of useable
> time left in a battery ... the battery people are of little help, this
> includes comapnies such as Gold Peak, Panasonic, Energizer and Varta!
>
> Hence, I have had to spend a large amount of time using GPIB
> controlled DVM's to measure batteries while being charged and
> discharegd.
>
> Mike, what method did you use for the product to give a user an
> indication that the battery was failing? ... I have been playing with
> usign either an absolute measure or rate of change of the battery
> voltage.
>
> kind regards,
> SW.
>
> PS. I think this thread is great, it is easy to tell from the tone
> that people are writing in that there is a mutual appreciation of the
> headache these 'simple' devices cause. But hey .. its only software
> 8-)
>
> ______________________________ Reply Separator
> Subject: Re: Batteries [OT]
> Author: RemoveMEwwlKILLspamnetcomuk.co.uk at INTERNET
> Date: 21/11/97 09:36
>
> >Manufacturers don't say much about the capacity of alkaline batteries, I
> >think a safe assumption would be about 4x the capacity of the same size
> >Ni-Cd. But not rechargeable, or rechargeable only a small number of
> >times. This is the least expensive battery system to manufacture, since
> >the user pays someone else for the batteries.
> I recently needed detailed discharge curve info on alkalines, and was
> staggered to find that Duracell couldn't supply anything othr than a
> couple of reference curves at specific loads & temps. Surely these guys
> have been making batteries long enough to be able to supply a simple
> program which would give a discharge curve at any given load & temp
> (i.e. what the customer really NEEDS) - apparently not! We had to spend
> a lot of time testing, as we had to provide a lo-bat warning with a
> specific amount of running time available (due to the standards the
> product had to comply with). Lack of info was a REAL pain.
> ____ ____
> _/ L_/ Mike Harrison / White Wing Logic / wwlSTOPspamspam_OUTnetcomuk.co.uk _/ L_/
> _/ W_/ Hardware & Software design / PCB Design / Consultancy _/ W_/
> /_W_/ Industrial / Computer Peripherals / Hazardous Area /_W_/
Sorry I'M not Mike, but this is Piclist, and here is my advice.
If you charge your battery, measure the energy you put in.
In your system, measure the energy sucked away from the battery,
then discharge completely your battery; don't forget
to measure it's expiration energy.
Then compute the lossssss.
A perfect battery has no loss, nobody's perfect.
Watch the loss !
Here i want to cite the appropriate song for the circumstance.
"You can watch them die... Live on T.V. "
This song is from "The BOX"
Batteries are good for human beeing, given them a reasonable retiremnt
time
before they pass away.
>
> Battery performance information is extremely hard to get hold of. We
> are making a product at the moment that needs to incorporate both a
> battery charger and a mechansim for determining the amount of useable
> time left in a battery ... the battery people are of little help, this
> includes comapnies such as Gold Peak, Panasonic, Energizer and Varta!
>
> Hence, I have had to spend a large amount of time using GPIB
> controlled DVM's to measure batteries while being charged and
> discharegd.
>
> Mike, what method did you use for the product to give a user an
> indication that the battery was failing? ... I have been playing with
> usign either an absolute measure or rate of change of the battery
> voltage.
>
> kind regards,
> SW.
>
> PS. I think this thread is great, it is easy to tell from the tone
> that people are writing in that there is a mutual appreciation of the
> headache these 'simple' devices cause. But hey .. its only software
> 8-)
>
In message <spamBeGoneyam7265.2652.137806280STOPspamEraseMEmail.ipsnet.it>, Alessandro Zummo
<KILLspamazummospamBeGoneita.flashnet.it> writes
>Il 21-Nov-97, Nigel Goodwin scrisse:
>
>
>
>>A couple of years ago I plotted discharge curves for a number of
>>different AA size batteries feeding a small torch bulb (it seemed a
>>reasonable load to use!). If anyone is interested let me know, and I'll
>>dig the results out and stick them on my web site.
>
>I'm interested.. plese let me know!
>
I've placed the graphs on my site in the miscellaneous pages, linked
from the main index page.
I've sent a copy of this to the PicList as well, in case anyone there is
interested.
--
Nigel.
/--------------------------------------------------------------\
| Nigel Goodwin | Internet : EraseMEnigelgEraseMElpilsley.demon.co.uk |
| Lower Pilsley | Web Page : http://www.lpilsley.demon.co.uk |
| Chesterfield | |
| England | |
\--------------------------------------------------------------/
> In message <@spam@yam7265.2652.137806280@spam@spam_OUTmail.ipsnet.it>, Alessandro Zummo
> <spamBeGoneazummoKILLspamita.flashnet.it> writes
> >Il 21-Nov-97, Nigel Goodwin scrisse:
> >
> >
> >
> >>A couple of years ago I plotted discharge curves for a number of
> >>different AA size batteries feeding a small torch bulb (it seemed a
> >>reasonable load to use!). If anyone is interested let me know, and I'll
> >>dig the results out and stick them on my web site.
> >
> >I'm interested.. plese let me know!
> >
>
> I've placed the graphs on my site in the miscellaneous pages, linked
> from the main index page.
>
> I've sent a copy of this to the PicList as well, in case anyone there is
> interested.
>
>
Hi,
About 12 months ago I got a battry discharge program from a news group. It
provides discharge graphs for both Nicads and Alkalines.
The best feature is that you can defines loads with duty cycle, converters
with
efficency, etc. For example, the efficency of a voltage regulator can be
entered, the current consumption of the PIC in active, and standby modes can
be entered, the load of any peripherals an be entered. These are all entered
with their duty cycles and relationships, i.e. battery - regulator - PIC. The
number, type and capacity of the battery are entered. The program then gives
a discharge profile for the systems usage. Good for estimating the battery
life for a particular application.
The program was a beta version, and not freeware. I've had a quick
evaluation, but plan to use it in about 4 months. The disk is at home. If
anybody is interested I will get the details of the author etc.
Regards,
Peter.
--
Peter Homann email: .....peterhspam_OUTadacel.com.au Work : +61 3 9596-2991
Adacel Technologies Ltd Fax : +61 3 9596-2960
250 Bay St, Brighton 3186, VIC, AUSTRALIA Mobile : 014 025-925 http://www.adacel.com.au Australian Software Engineering Excellence
wasp.co.za
