ml wrote:

gosh, i sure do appreciate everybody's help, sincerely, but alas, i
still have no concise way to calculate what size battery or cap i need

Please pardon the dumb question, but if you have a 100 watt fuel cell
why do you need a battery?

73, Jim AC6XG

ml wrote:

issues. So you would probably be well served by one of the 7AH UPS
batteries from a place such as Batteries Plus. They cost about $25 and
are about 7"Lx2"Wx4"H.

tom
K0TAR


gosh, i sure do appreciate everybody's help, sincerely, but alas, i
still have no concise way to calculate what size battery or cap i need


I thought my statement was clear, but I will repeat it -

"So you would probably be well served by one of the 7AH UPS batteries
from a place such as Batteries Plus. They cost about $25 and are about
7"Lx2"Wx4"H." Float that across your fuel cell and you will be fine.

Of course, if the fuel cell doesn't put out at least 13.5 vclts with
your rig on receive, a "12 volt" float battery won't have enough charge
in it to speak of. Then it would be back to capacitors and the
interesting problem that they would bring along. Such as a 0 volt
charge current that could possibly be damaging to your fuel cell.

This whole thing seems a very expensive way to have not very good
portable power. You have never stated why you must have a fuel cell.
Would you care to enlighten us?

tom
K0TAR

wrote:
Jim - NN7K wrote:
Always wanted a 1 FARAD (or bigger) capacitor!
Where can you buy one?? (Short of buying a
"Charged "one, I.E. Storage Battery)? Oh
well only 6 Months to April First!
Jim NN7K


Richard Clark wrote:



Not unless you can assemble a couple hundred Farads (note the complete
absence of pico, nano, or micro in that Farads). The short version is
DON'T GO THERE.

73's
Richard Clark, KB7QHC

Why settle for a measly 1 F when you can have 50 F?

Go to www.digikey.com and search for 283-2511-ND.

--
Jim Pennino

Remove .spam.sux to reply.

And if the 5W output rig draws an amp on transmit, that 50F cap will
run it for 50 seconds with a one-volt drop. Compare that with an
inexpensive little 7Ah 12V gel-cell battery that will run it for
probably five hours. Caps may make sense to smooth over short pulses
of current, but seem like a poor solution for storing long-term energy.

The OP's question is so basic that I wonder if he's pulling our
collective legs.
--How many amps does the rig draw in transmit? In receive?
--How long do you want the aux power source to run it?
----how many hours of transmit; how many hours of receive?
--That tells you the minimum Ah rating for the aux battery.
--Use I = C * dV/dt and how much voltage drop you can stand
to figure the size capacitor you'd need to do the same thing
for an aux capacitor (and then discard the idea in favor of a
much cheaper battery).

Cheers,
Tom

I thought my statement was clear, but I will repeat it -

"So you would probably be well served by one of the 7AH UPS batteries
from a place such as Batteries Plus. They cost about $25 and are about
7"Lx2"Wx4"H." Float that across your fuel cell and you will be fine.

Of course, if the fuel cell doesn't put out at least 13.5 vclts with
your rig on receive, a "12 volt" float battery won't have enough charge
in it to speak of. Then it would be back to capacitors and the
interesting problem that they would bring along. Such as a 0 volt
charge current that could possibly be damaging to your fuel cell.

OK, that was clear, i sorta thought it seemed a bit small, and figured
you calculated at 100ah nnot 100w my bad

This whole thing seems a very expensive way to have not very good
portable power. You have never stated why you must have a fuel cell.
Would you care to enlighten us?

tom
K0TAR

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

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

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

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

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

"ml" wrote in message
...

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 bet you also find that storing explosive gasses in an apartment are also
against code. and laywers would probably consider a fuel cell a generator
also.

your best bet is to just keep a few gell cells around to run your vhf on low
power, you can get many hours on a charge... when one dies, swap for another
one, take it out to your car, charge it from there, and bring it back in.

remember, in an emergency you most likely won't be making long transmissions
anyway, first because there won't be that many locals to talk to because
most of them won't have power... repeaters will be tied up with emergency
traffic, and unless you are a net control you should mostly be listening.

In article ,
"Dave" wrote:

i bet you also find that storing explosive gasses in an apartment are also
against code. and laywers would probably consider a fuel cell a generator
also.

Well not really, as a lot of apartments have Explosive GAS piped right
into them..... Never heard of Natural Gas, or even Propane, I guess....
Both are Extremely Explosive, when mixed with air in the correct
ratio.... Duh.....