Re: Power For QRP


From: Randy (
Date: Wed Jan 12 1994 - 17:23:23 EST

> Good afternoon all;
> I am getting setup for QRP ( I have one of the NorCal 40 kits on order) and I am
> looking into power options. I was wondering how much batter folks generally
> take along.

Pancake batter does not last too long...I'd say 3 cups per person per day.

> I have various sizes of gel cells, but I like my little 2AH 12
> cells. I was tinking about one or two of them and a wall,solar charger system I
> am designing. Anybody got some input?

1st...solarcells: put a 1N4001 diode and a 10 ohm resistor in series with
the solar cell bank, to protect them in case the sun lite gets dim or out,
and the battery is still connected...else you can damage the cells....and
run the battery down.

Makes charging like it should be: care-free and automatic (enough, for your

Lets assume the rig draws 100ma avg on receive.
Lets assume 8 hr a day of use
Lets assume you spend 3 hours ACTUALLY transmitting ( key tapped down, total
accumulated time)

JUST receiving, you will run the batterys out in 20 hours (omitting any
Transmitting...assume rig pulls send time will be...about 2 1/2
hours....or....sending/receiving, you might just make it for one 8 hour stretch.

Now add the solar charger.

EXPECT to only get 4 hours of USFUL charge per day ( clouds, overcast, and
shadows cast by trees due to less than optimum placement of solar panel)

A 2AH battery ---if you want it to live a long time---should not be charged
heavier than 200ma for 15 hours.
400ma for 7.5-8 hours would be as heavy as I would want to recharge them.

How much amperage does your solar panel put out?

Lets say it does 500ma, just to figure all this roughly.

Thats .5 amps for 4 real hour...2 amp hours ( tranlates to 1.5 amp charge-hours
due to batterys being a bit 'wasteful')

Your solar panel will only help to slow down the total run out of the battery
thus extend your running time some.

No..a bigger solar panel can't be used or you may hurt the battery...but, if
you keep battery as a back up, and wire a big solar panel to 'charge' a large
bank of capacitors ( enough to make 1,000,000 uf or more @ 15 vdc rating)
then you could run direct off THAT......capacitors act as your current
reserve, for when you transmit...and gets you thru any short duration
cloud-pass overs.
You'd keep the battery for when the sun isn't brite enough to do the job. you have 2 ways to go, and have a rough idea how long you can go.

Last nite, around 3-5 am, on 3700kc, I heard broadcast station Doitch Vella
(the German one with the chimes-ID) fluttering in and out.

NO...was not IMD nor Image...they were THERE!.....lasted about 1 hour and
they faded out, slowly.

Randy KA1UNW              If you get a shock while
                         servicing  your  equipment,         "Works for me!"
randy@             DON'T  JUMP!                     -Pete Keyes
                     You might break an expensive tube!

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