[aprssig] Solar Powered Digi's.
wa2mct at mearle.com
Tue Dec 4 13:44:19 CST 2007
John Ronan wrote:
> On 4 Dec 2007, at 18:53, Phillip B. Pacier wrote:
>> I had a solar powered digi up for five years (W7RBV-2). I have since
>> transferred ownership of the digi and it is no longer solar powered,
>> but what what information are you looking for?
> Typical "Rules of thumb" I guess for battery/panel sizing.
> I was thinking of a OT2 and maybe a FT-1500 or some other dedicated 2m
> Radio. The OT2 will also broadcast battery voltage as telemetry for me.
> Its not something we've done before.. so avoiding any 'gotchas' would help.
> Apparently, the 'average' Sun hours per day over here is about 3.75. So
> I was going to go for a rough figure of TX'ing 20% of the time, and try
> and size the battery so that it never gets discharged below 80% on that
> figure. And then I guess, size the panel so that it could recharge the
> battery from roughly 80% discharge on a 3.5 hour day of sun. Does that
> sound reasonable?
Those are reasonable numbers, but no synthesized radio.
They are not optimized for stand by.
Let's say you transmit 20% of the time. That's 288 minutes of
transmitter time, or, say at 2a 288 x 2a = 576 amp-minutes or 9.6
Now then. 100 ma (0.1 amp) of stand-by for 1152 minutes
1152 x .1 = 115.2 amp-minutes, or 1.92 amp-hours.
Oops. The 1500 shows .3 amp squelched. More while receiving.
So 1152 x .3 = 345.6 amp-minutes or 5.76 amp-hours.
Of course, there will be receiving time and the current there is 0.6a
for that radio.
So you are looking at a power budget of 7.68 or so amp-hours/day.
Notice that the standby time is a significant part of your power budget.
You would want to find a transceiver which can draw much less current.
Use a crystal radio, and remove or disable / disconnect the audio
portion of the receiver - you just need to buffer discriminator audio.
You could get the standby requirement down to on the order of 0.05 a vs
0.30 a. Save you a lot of energy.
Just some thoughts.
) ) de WA2MCT Mark
( ( Echolink 99190 Grid Square EL17HQ
) ) You will be assimilated... oooh, coffee!!
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