Author Topic: How to -- SHTF emergency power  (Read 18202 times)

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BTPost

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Re: How to -- SHTF emergency power
« Reply #30 on: March 13, 2012, 01:31:06 AM »
The issue is ALWAYS, AMPHours Out need to be replaced with 125% AMPHours In....So if you are running 100WattsRF Out, at at 12.5 Vdc, that is like 16AMPs * the Time of Tx, plus 1 AMP for the amount of RX Time Will Equal the Total AMPHours sucked from the Battery.  So if your driving somewhere, and your Vehicle Alternator can do the recharging, No Issue. But if your NOT running the Engine, and sucking that $4.35+/USG Gasoline, then you need to figure where that Recharge Energy needs to come from. Solar takes a lot of surface area, and is pretty fragile, to make a permanent Mounting solution, especially on a Car or Truck. So really not all that practical.  Just Say'en.... YMMV....
Bruce in alaska AL7AQ

spacecase0

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Re: How to -- SHTF emergency power
« Reply #31 on: March 13, 2012, 12:08:45 PM »
something that lots of people seem not to know is that lead acid batteries are about 50% efficient
most of that low efficiency is due to the charge voltage being higher than the discharge voltage,
so if you plan on using 100W hours from a battery, then plan on having 200W hours of solar to charge it.

also most full size HF radios tend to suck up the power fairly fast,
the ft-857 and ft-897 have battery modes that save lots of power (on the 857 it is turned on with grounding a seemingly unused wire on the power connector), but they still pull way more than the ft-817 with it's matching power amp.
so if you are planning to run in solar power mode, think about efficiency of your radio when going to chose a radio to get.