# Frequency of batteries

Discussion in 'Electronic Design' started by blazingbadger, Oct 3, 2007.

Our tech service guys like to joke around about customers asking this
question. But what is the correct answer?

They say zero because ideally the voltage should never macroscopically
change.

For the sake of argument I say infinity because the voltage is
constantly microscopically changing.

Of course you could also make an argument about discharge rates and
the voltage changing.

Frequency is usually defined in electrical systems using a time
interval of one second and a complete oscillation so this might be
suspect, but it's open to interpretation.

2. ### Martin GriffithGuest

It's the reciprical of how often you have to pay for sex. It can't be
infinite, since the DC would have to been available at the Big Bang
(sorry sex again), which is slightly longer than the availability of
of manufactured batteries, ie 6000years

Martin

3. ### CharlesGuest

Philosophical issues of this type cannot be resolved. The Fourier transform
for zero bandwidth requires that the condition has always existed and always
will. Sounds like God to me.

4. ### Stanislaw FlattoGuest

For 'zero' change you need 'ideal' component. When you find such keep it
for references.
All others will have responses to changing conditions, easiest way to
find is to introduce those changes and measure.

Been there, done it.

Stanislaw.

5. ### D from BCGuest

The more drain over time...the higher the frequency of battery
changes.
High frequency batteries are those cheapo dollar store zincs.
You'll be changing those frequently

ok.. Maybe that wasn't very funny..

Check out parasitic internal inductance of batteries.

D from BC

6. ### Phil AllisonGuest

** The "frequency" of a battery is how " frequently " you change or
recharge it.

Charging and discharging a battery is called " cycling ".

The life span of a rechargeable cell is determined by the number of "cycles"
it can accept without deterioration

....... Phil

7. ### John LarkinGuest

The concept is meaningless, so don't worry about it.

John

8. ### Michael A. TerrellGuest

Is a 'blazing badger' anything like a 'flaming ferret'?

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

9. ### BenjGuest

Yeah, million yuks! I remember when me and my buds were smart-asses in
High school asking the physics teacher if there was an AC battery.
Huh, Huh, huh! (He had no idea, natch)
Not so. A battery has a frequency distribution not a single
frequency! The waveform of which one takes a Fourier transform would
be a sort of step up to the battery voltage (occurs when the battery
was manufactured) followed by a slow decay to zero as the battery
ages. These are pretty low frequencies but not anywhere near zero.
Yes this is true as well and often can cause problems (noise) in
battery powered circuits. Since he voltage output of the battery comes
from chemical effects of the atoms and larger particles making up the
materials of the battery, the output voltage is not pure DC (or more
exactly the pure decaying waveform we talked about above) but rather
has relatively high frequency noise on it because of stochastic
processes in the battery. However, the spectrum of this noise does NOT
extend to infinity or even to high radio frequencies because a battery
is a chemical device and chemical processes have certain speed
limitations. This is the same effect that makes electrolytic
capacitors poor filters at very high frequencies. The chemical actions
simply can't follow the frequencies. So infinity is wrong as well.
The definition of frequency is OK, but really we are talking here
about frequency distributions or essentially a frequency density.

So does this make sense yet?

10. ### Rene TschaggelarGuest

The correct question would have been the one

Rene

11. ### Richard HenryGuest

And that depends dramatrically on how you define "deterioration".

12. ### D from BCGuest

Perhaps it's a problem to use a 1.5V cell to power a microwave
oscillator with no supply bypass capacitors.

D from BC

13. ### colinGuest

based on 5 yr battery life, fundemental would be aproximatly
0.00000004 hz

Colin =^.^=

14. ### Rich GriseGuest

It depends on the rise-time when you switch it on. ;-)

But seriously, "frequency" is just not applicable to batteries. They're
"DC".

Of course a true DC signal would have had to have started before time
began, and stay steady until the end of time, but for practical purposes,
it's not worth bothering with other than as an intellectual exercise.

Hope This Helps!
Rich

15. ### GibboGuest

It's not often you make me giggle Grise but that did.

16. ### Rich GriseGuest

Huh? It was the Big Bang that was 6000 years ago?

Oh, yeah, I guess that was the First Day. I don't remember which day it
was when He plopped Earth into place, with all of the dinosaur fossils and
evidence of plate tectonics already in place, evidently to give us all
something to argue about 'til the end of time, which was supposed to have
happened about 6 1/2 years ago. ;-)

Cheers!
Rich

17. ### Rich GriseGuest

Car batteries, about once every five years or so. ;-)

Flashlight batteries, it depends on how much you use it.

NiMH, about 1/(a few days). >:-[ (I'll never waste my money on
NiMH again!)

Cheers!
Rich

What were you using them in? One area where NiMh do considerably worse than
NiCds is in high-drain devices -- the internal resistance of NiMh is *much*
higher than NiCds, so in high-drain devices their terminal voltages hits "end
of battery life" much sooner. See, e.g.,
http://www.buchmann.ca/chap9-page1.asp

19. ### Michael A. TerrellGuest

I'd guess that he had heard that lame joke for so many years that he
couldn't even fake a grin, and didn't want to encourage the idiots.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

20. ### Don LancasterGuest

The correct term is EIS, short for electronic impedance spectroscopy.
In which all frequencies are dealt with.

Further the frequencies depend upon the Fourier spectrum of the duty cycle.

More on my website.

--
Many thanks,

Don Lancaster voice phone: (928)428-4073
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552