Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1   Report Post  
Old October 27th 06, 04:04 AM posted to rec.radio.amateur.antenna
external usenet poster
 
First recorded activity by RadioBanter: Jul 2006
Posts: 230
Default ans calculations/ fuel cell battery buffer or cap?

ml wrote:

well if one had to buy the jado it might be expensive, i can get one
much cheeper than list and somone here posted an incorrect list price
anyways , - then again if you add up the total cost of the
competition you'd at worst case be in the ball park

the goal was at first to power a hf/rig 100w tx for a few days on a
backup power source looking at batteries/fuelcells i realized this is to
much load so i figured my 2m righ on low pwr is a compramise @1week

at 100w tx, i started to put together on paper what i need, a pretty
big charger lots of very big heavy batteries , and they are VERY
expensive, if the batteries went 'low' and the power wasn't restored
say an extended blackout then the battery life goes down the tubes

now i live in an apt, so too many batteries even if free arent practical

code prevents me from using a generator in the building, so would the
coop board, and the noise, smell vibration and mostly a generator
running would attract 'undesiables' it would be kinda cheep and
storing say desil wouldn't be a big deal if say i had a pvt house
again thou getting extra fuel in a extended blackout would be an issue

i had a demo of this fuel cell i was really impressed, is the cost and
power output totally there no i guess not a few years from now prob
but the cost of the fuel cell unit alone is comparable to the battery
cost and i don't have to worry about the space, and other issues
associated w/batteries

i can get a small tank of hydrogen that would power the unit for longer
than i was planning for it's cheep and i can get it very easy even if
theyre was an extended blackout (details omitted) it's quite meets
code, very small, very light dosn't pollute or stink

seemed rather sexy the jado can also be powered from small cartridges
making the unit selfcontained and very portable, however this isn't a
requirement of mine but cool benni

the only con for me, seems to be a)not totally going to give me 100w
at full load b) i wish the unit was more than a puny 100w the larger
units i would have to pay full list for and are therefore outta reach


so solar /wind again might be nice in a pvt home but nothing i'd
rely on

it usually starts simple, i wanted somthing better than battery power

much appreciation
and mostly also because i like to tinker and learn seems like somthing
cool to play with and experiment


Ok, I have applied a simple power budget to what you stated your
original desire was, as opposed to your cut down 2m 5W system.

Using a rig I own, an FT-897, on HF.

Assume 90% receive at 1 amp.
Assume 10% transmit at 15 amps with 100 watts output, (measured as
opposed to the 22 amps claimed in the docs)

This gives 2.4 amps average consumption. (Check my math, the doctor did
a lot during my pre-op today)

1 week is 168 hours which gives us 403 ampere hours.

100AH deep cycle batteries are around 100 each (or less), So that's
about $400 for all the batteries you need for a week without sleep.

A modern top of the line charger, such as produced by Schumacher, is
less than $100, does automatic desulfation, will charge at 50 amps or
greater, and weighs about 6 pounds.

So now we are at under 500 dollars for an emergency power for any ham
that needs to run an HF rig for a whole week.

I just don't see why you want to use the fuel cell, it makes no sense.

tom
K0TAR
  #2   Report Post  
Old October 27th 06, 05:06 AM posted to rec.radio.amateur.antenna
external usenet poster
 
First recorded activity by RadioBanter: Jun 2006
Posts: 1,374
Default ans calculations/ fuel cell battery buffer or cap?

Tom Ring wrote:
. . .
1 week is 168 hours which gives us 403 ampere hours.
. . .


which at 13.6 volts is about 5480 watt-hours. This is the energy storage
requirement.

The OP asked about using a capacitor. The energy stored in a capacitor
is C * V^2 / 2. For capacitance in farads and voltage in volts, the
result is joules, or watt-seconds -- you need 5480 * 3600 ~ 20,000,000
joules in round numbers. So suppose you wanted to store this same amount
of energy in a capacitor, and you had a switching regulator which would
handle 50 volts maximum input voltage. Solving for C, assuming it's
charged to 50 volts,

C = 20,000,000 * 2 / (50^2) = 16,000 farads.

This assumes you can get all the energy out of the capacitor, which
requires your regulator to work down to zero volts. But you'll get 3/4
of the energy out of it if your regulator cuts off at 25 volts, 7/8 if
it cuts off at 12.5 volts, etc.

How does that sound?

Roy Lewallen, W7EL
  #3   Report Post  
Old October 27th 06, 10:33 AM posted to rec.radio.amateur.antenna
ml ml is offline
external usenet poster
 
First recorded activity by RadioBanter: Jul 2006
Posts: 225
Default cap/ ans calculations/ fuel cell battery buffer or cap?

In article ,
Roy Lewallen wrote:

Tom Ring wrote:
. . .
1 week is 168 hours which gives us 403 ampere hours.
. . .


which at 13.6 volts is about 5480 watt-hours. This is the energy storage
requirement.

The OP asked about using a capacitor. The energy stored in a capacitor
is C * V^2 / 2. For capacitance in farads and voltage in volts, the
result is joules, or watt-seconds -- you need 5480 * 3600 ~ 20,000,000
joules in round numbers. So suppose you wanted to store this same amount
of energy in a capacitor, and you had a switching regulator which would
handle 50 volts maximum input voltage. Solving for C, assuming it's
charged to 50 volts,

C = 20,000,000 * 2 / (50^2) = 16,000 farads.

This assumes you can get all the energy out of the capacitor, which
requires your regulator to work down to zero volts. But you'll get 3/4
of the energy out of it if your regulator cuts off at 25 volts, 7/8 if
it cuts off at 12.5 volts, etc.

How does that sound?

Roy Lewallen, W7EL


well i guess it sounds like i wont have any 16,000 farad cap's stacked
up in my myplace anytime soon, but i understand the math behind it
now thanks

perhaps i'll just get a small cap to handle a brief second keydown dip
smooth things out a bit

thanks
  #4   Report Post  
Old October 28th 06, 01:30 AM posted to rec.radio.amateur.antenna,rec.radio.amateur.policy
external usenet poster
 
First recorded activity by RadioBanter: Jul 2006
Posts: 4,113
Default ans calculations/ fuel cell battery buffer or cap?

Roy Lewallen wrote in
:

Tom Ring wrote:
. . .
1 week is 168 hours which gives us 403 ampere hours.
. . .


which at 13.6 volts is about 5480 watt-hours. This is the energy storage
requirement.

The OP asked about using a capacitor. The energy stored in a capacitor
is C * V^2 / 2. For capacitance in farads and voltage in volts, the
result is joules, or watt-seconds -- you need 5480 * 3600 ~ 20,000,000
joules in round numbers. So suppose you wanted to store this same amount
of energy in a capacitor, and you had a switching regulator which would
handle 50 volts maximum input voltage. Solving for C, assuming it's
charged to 50 volts,

C = 20,000,000 * 2 / (50^2) = 16,000 farads.

This assumes you can get all the energy out of the capacitor, which
requires your regulator to work down to zero volts. But you'll get 3/4
of the energy out of it if your regulator cuts off at 25 volts, 7/8 if
it cuts off at 12.5 volts, etc.

How does that sound?

Roy Lewallen, W7EL



Send that to me in CW and I'll have a look at it.

SC
  #6   Report Post  
Old October 27th 06, 11:01 AM posted to rec.radio.amateur.antenna
ml ml is offline
external usenet poster
 
First recorded activity by RadioBanter: Jul 2006
Posts: 225
Default preop/ ans calculations/ fuel cell battery buffer or cap?

In article ,
Tom Ring wrote:

ml wrote:
omitted) it's quite meets
code, very small, very light dosn't pollute or stink

seemed rather sexy the jado can also be powered from small cartridges
making the unit selfcontained and very portable, however this isn't a
requirement of mine but cool benni

the only con for me, seems to be a)not totally going to give me 100w
at full load b) i wish the unit was more than a puny 100w the larger
units i would have to pay full list for and are therefore outta reach


so solath and experiment


Ok, I have applied a simple power budget to what you stated your
original desire was, as opposed to your cut down 2m 5W system.

Using a rig I own, an FT-897, on HF.

Assume 90% receive at 1 amp.
Assume 10% transmit at 15 amps with 100 watts output, (measured as
opposed to the 22 amps claimed in the docs)

This gives 2.4 amps average consumption. (Check my math, the doctor did
a lot during my pre-op today)

1 week is 168 hours which gives us 403 ampere hours.

100AH deep cycle batteries are around 100 each (or less), So that's
about $400 for all the batteries you need for a week without sleep.

A modern top of the line charger, such as produced by Schumacher, is
less than $100, does automatic desulfation, will charge at 50 amps or
greater, and weighs about 6 pounds.

So now we are at under 500 dollars for an emergency power for any ham
that needs to run an HF rig for a whole week.

I just don't see why you want to use the fuel cell, it makes no sense.

tom
K0TAR

tom, am i to understand you had some surgery today? if so, i hope all is
well with you and taking the time to write is appreciated

i am guessing roy's calculation of the total ampre hrs needed is closer
to being correct, but it's 5am and i kinda don't know how to calculate
that so i dunno as stated in my earlier post i don't have the formulas
so i can't act to confirm but i nod my head and presume it's all correct
based on roys math

you are correct about what the rig is doing mine is exactly simular i
would calculate based on 20amps

re your last comments on why i would want a fuel cell, it should be very
clear in all my many posts

5480 watt-hours of battery is more $$ and large than i have practical
room for

i can get the fuel cell for practically nothing and i just thought it
might be able to offer some useful power to top off a battery to
provide some b/u power why not? and also be a fun experiment it runs
quiet , clean and i can get all the fuel i want free always, i would
never be able to get fossel fuels in a blackout or other emerg

so now i inch a drop closer knowing how many what hours my original
abandoned goal would draw , however my current stated goal is to just
power my 5w tx output(draws4amps) 2m mobile rig

and try to calculate how much the battery would be drained in a 1min
tx and then see if the 12v 7amps comming out of the jado would recharge
it fast enough i believe that is what must be calculated for just not
sure how do it, unless you still say a 7amp battery is still 'ok'

my goal was to be able to calculate

so a 7amp battery(or what ever is needed optically this seems like a too
low a #)) w/a 1min 4amp load would be ??%drained
then based on manuf spec's for the battery we could calculate how much
power &time would be needed to top it back off

then it would be simple enough to see if the output of the jado is
sufficient i think thats all thats needed i think that's simple
but i dunno how to calculate it
thanks all i really wanted to do
  #7   Report Post  
Old October 27th 06, 08:52 PM posted to rec.radio.amateur.antenna
external usenet poster
 
First recorded activity by RadioBanter: Jul 2006
Posts: 644
Default preop/ ans calculations/ fuel cell battery buffer or cap?


ml wrote:
In article ,
Tom Ring wrote:

ml wrote:
omitted) it's quite meets
code, very small, very light dosn't pollute or stink

seemed rather sexy the jado can also be powered from small cartridges
making the unit selfcontained and very portable, however this isn't a
requirement of mine but cool benni

the only con for me, seems to be a)not totally going to give me 100w
at full load b) i wish the unit was more than a puny 100w the larger
units i would have to pay full list for and are therefore outta reach


so solath and experiment


Ok, I have applied a simple power budget to what you stated your
original desire was, as opposed to your cut down 2m 5W system.

Using a rig I own, an FT-897, on HF.

Assume 90% receive at 1 amp.
Assume 10% transmit at 15 amps with 100 watts output, (measured as
opposed to the 22 amps claimed in the docs)

This gives 2.4 amps average consumption. (Check my math, the doctor did
a lot during my pre-op today)

1 week is 168 hours which gives us 403 ampere hours.

100AH deep cycle batteries are around 100 each (or less), So that's
about $400 for all the batteries you need for a week without sleep.

A modern top of the line charger, such as produced by Schumacher, is
less than $100, does automatic desulfation, will charge at 50 amps or
greater, and weighs about 6 pounds.

So now we are at under 500 dollars for an emergency power for any ham
that needs to run an HF rig for a whole week.

I just don't see why you want to use the fuel cell, it makes no sense.

tom
K0TAR

tom, am i to understand you had some surgery today? if so, i hope all is
well with you and taking the time to write is appreciated

i am guessing roy's calculation of the total ampre hrs needed is closer
to being correct, but it's 5am and i kinda don't know how to calculate
that so i dunno as stated in my earlier post i don't have the formulas
so i can't act to confirm but i nod my head and presume it's all correct
based on roys math

you are correct about what the rig is doing mine is exactly simular i
would calculate based on 20amps

re your last comments on why i would want a fuel cell, it should be very
clear in all my many posts

5480 watt-hours of battery is more $$ and large than i have practical
room for

i can get the fuel cell for practically nothing and i just thought it
might be able to offer some useful power to top off a battery to
provide some b/u power why not? and also be a fun experiment it runs
quiet , clean and i can get all the fuel i want free always, i would
never be able to get fossel fuels in a blackout or other emerg

so now i inch a drop closer knowing how many what hours my original
abandoned goal would draw , however my current stated goal is to just
power my 5w tx output(draws4amps) 2m mobile rig

and try to calculate how much the battery would be drained in a 1min
tx and then see if the 12v 7amps comming out of the jado would recharge
it fast enough i believe that is what must be calculated for just not
sure how do it, unless you still say a 7amp battery is still 'ok'

my goal was to be able to calculate

so a 7amp battery(or what ever is needed optically this seems like a too
low a #)) w/a 1min 4amp load would be ??%drained
then based on manuf spec's for the battery we could calculate how much
power &time would be needed to top it back off

then it would be simple enough to see if the output of the jado is
sufficient i think thats all thats needed i think that's simple
but i dunno how to calculate it
thanks all i really wanted to do


If your rig draws 4 amps (I assume that's on transmit; it would be an
awful lot of power for a modern receiver), and the fuel cell can put
out 7 amps continuously albeit at slightly reduced voltage, and I
assume it can put out 4 amps at less of a reduction, why are you
worried about it? Unless you are VERY long-winded with your
transmissions, a small 7amp-hour sealed lead acid battery would give
you a couple hours operating time even if it wasn't being continuously
recharged. I'd actually opt instead for some voltage stabilization at
the fuel cell output: a buck-boost regulator would do it. If you
trust the fuel cell to do its job, then trust it. If you don't, then
provide a backup. So what I read between the lines you've written is
that you're going to get this fuel cell, but you don't really trust it.
You don't even trust it to come close to what are apparently its
published ratings.

Pretty much all the formulas you need to figure all this stuff out:
power = voltage times current (watts = volts * amps)
energy = power times time (joules = watts * seconds)
-- total energy needed = sum of (each current times the length
of time that current is drawn)
amp-hours = amps * hours = amps * seconds / 3600sec/hr
battery energy storage in watt-hours = amp-hour rating * volts
(assuming full charge)
battery energy storage in joules = amp-hour rating * volts * 3600
sec/hour
capacitor energy storage = (initial charge voltage)^2 * capacitance / 2
joules = watt-seconds = volts^2 * farads / 2
watt-hours = joules/3600 = volts^2 * farads / 7200

Where is it that you can get a license without knowing at least this
much? Why so much trouble with the concepts of power and energy
calculated from current, voltage and time? (Why is this posted to an
antennas newsgroup?)

Cheers,
Tom

  #8   Report Post  
Old October 27th 06, 11:07 PM posted to rec.radio.amateur.antenna
external usenet poster
 
First recorded activity by RadioBanter: Jul 2006
Posts: 666
Default preop/ ans calculations/ fuel cell battery buffer or cap?

K7ITM wrote:

-- total energy needed = sum of (each current times the length
of time that current is drawn)


You probably meant to say current times time is total charge.

73 de AC6XG

  #9   Report Post  
Old October 28th 06, 02:01 AM posted to rec.radio.amateur.antenna
external usenet poster
 
First recorded activity by RadioBanter: Jul 2006
Posts: 644
Default preop/ ans calculations/ fuel cell battery buffer or cap?


Jim Kelley wrote:
K7ITM wrote:

-- total energy needed = sum of (each current times the length
of time that current is drawn)


You probably meant to say current times time is total charge.

73 de AC6XG


Yeah, probably something like that. ;-) Actually, what I meant to
write was more like:
-- total energy needed = voltage * sum of (each current times the
length
of time that current is drawn.

Lesseee...unit analysis...volts * amps * time. OK, that looks better.

Thanks, Jim.

Cheers,
Tom

  #10   Report Post  
Old October 27th 06, 09:18 PM posted to rec.radio.amateur.antenna
external usenet poster
 
First recorded activity by RadioBanter: Jul 2006
Posts: 644
Default preop/ ans calculations/ fuel cell battery buffer or cap?


ml wrote:
In article ,
Tom Ring wrote:

ml wrote:
omitted) it's quite meets
code, very small, very light dosn't pollute or stink

seemed rather sexy the jado can also be powered from small cartridges
making the unit selfcontained and very portable, however this isn't a
requirement of mine but cool benni

the only con for me, seems to be a)not totally going to give me 100w
at full load b) i wish the unit was more than a puny 100w the larger
units i would have to pay full list for and are therefore outta reach


so solath and experiment


Ok, I have applied a simple power budget to what you stated your
original desire was, as opposed to your cut down 2m 5W system.

Using a rig I own, an FT-897, on HF.

Assume 90% receive at 1 amp.
Assume 10% transmit at 15 amps with 100 watts output, (measured as
opposed to the 22 amps claimed in the docs)

This gives 2.4 amps average consumption. (Check my math, the doctor did
a lot during my pre-op today)

1 week is 168 hours which gives us 403 ampere hours.

100AH deep cycle batteries are around 100 each (or less), So that's
about $400 for all the batteries you need for a week without sleep.

A modern top of the line charger, such as produced by Schumacher, is
less than $100, does automatic desulfation, will charge at 50 amps or
greater, and weighs about 6 pounds.

So now we are at under 500 dollars for an emergency power for any ham
that needs to run an HF rig for a whole week.

I just don't see why you want to use the fuel cell, it makes no sense.

tom
K0TAR

tom, am i to understand you had some surgery today? if so, i hope all is
well with you and taking the time to write is appreciated

i am guessing roy's calculation of the total ampre hrs needed is closer
to being correct, but it's 5am and i kinda don't know how to calculate
that so i dunno as stated in my earlier post i don't have the formulas
so i can't act to confirm but i nod my head and presume it's all correct
based on roys math

you are correct about what the rig is doing mine is exactly simular i
would calculate based on 20amps

re your last comments on why i would want a fuel cell, it should be very
clear in all my many posts

5480 watt-hours of battery is more $$ and large than i have practical
room for

i can get the fuel cell for practically nothing and i just thought it
might be able to offer some useful power to top off a battery to
provide some b/u power why not? and also be a fun experiment it runs
quiet , clean and i can get all the fuel i want free always, i would
never be able to get fossel fuels in a blackout or other emerg

so now i inch a drop closer knowing how many what hours my original
abandoned goal would draw , however my current stated goal is to just
power my 5w tx output(draws4amps) 2m mobile rig

and try to calculate how much the battery would be drained in a 1min
tx and then see if the 12v 7amps comming out of the jado would recharge
it fast enough i believe that is what must be calculated for just not
sure how do it, unless you still say a 7amp battery is still 'ok'

my goal was to be able to calculate

so a 7amp battery(or what ever is needed optically this seems like a too
low a #)) w/a 1min 4amp load would be ??%drained
then based on manuf spec's for the battery we could calculate how much
power &time would be needed to top it back off

then it would be simple enough to see if the output of the jado is
sufficient i think thats all thats needed i think that's simple
but i dunno how to calculate it
thanks all i really wanted to do


If your rig draws 4 amps (I assume that's on transmit; it would be an
awful lot of power for a modern receiver), and the fuel cell can put
out 7 amps continuously albeit at slightly reduced voltage, and I
assume it can put out 4 amps at less of a reduction, why are you
worried about it? Unless you are VERY long-winded with your
transmissions, a small 7amp-hour sealed lead acid battery would give
you a couple hours operating time even if it wasn't being continuously
recharged. I'd actually opt instead for some voltage stabilization at
the fuel cell output: a buck-boost regulator would do it. If you
trust the fuel cell to do its job, then trust it. If you don't, then
provide a backup. So what I read between the lines you've written is
that you're going to get this fuel cell, but you don't really trust it.
You don't even trust it to come close to what are apparently its
published ratings.

Pretty much all the formulas you need to figure all this stuff out:
power = voltage times current (watts = volts * amps)
energy = power times time (joules = watts * seconds)
-- total energy needed = sum of (each current times the length
of time that current is drawn)
amp-hours = amps * hours = amps * seconds / 3600sec/hr
battery energy storage in watt-hours = amp-hour rating * volts
(assuming full charge)
battery energy storage in joules = amp-hour rating * volts * 3600
sec/hour
capacitor energy storage = (initial charge voltage)^2 * capacitance / 2
joules = watt-seconds = volts^2 * farads / 2
watt-hours = joules/3600 = volts^2 * farads / 7200

Where is it that you can get a license without knowing at least this
much? Why so much trouble with the concepts of power and energy
calculated from current, voltage and time? (Why is this posted to an
antennas newsgroup?)

Cheers,
Tom



Reply
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Running a radio from a large rechargeable cell or battery bpnjensen Shortwave 55 November 2nd 05 04:56 AM
Running a radio from a large rechargeable cell or battery [email protected] Shortwave 1 October 30th 05 03:32 AM
MAHA MH-C777PlusII MAHA MH-C777 battery reconditioner recommendation? fancy nospam tunes General 0 April 23rd 05 03:57 PM
Loose connection inside D cell battery Gary Schafer Homebrew 12 May 24th 04 04:24 AM
Loose connection inside D cell battery Gary Schafer Homebrew 0 May 21st 04 04:07 AM


All times are GMT +1. The time now is 07:07 AM.

Powered by vBulletin® Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
Copyright ©2004-2025 RadioBanter.
The comments are property of their posters.
 

About Us

"It's about Radio"

 

Copyright © 2017