[aprssig] Emergency Power for Ham stuff
vk2tv at exemail.com.au
Tue Jan 19 15:20:45 CST 2016
Are you seriously suggesting that hams tap into what is a potentially
lethal power supply, without warning about the dangers such a scheme
presents, not to mention the legal implications in places like Australia?
I can understand your desire to pursue alternate and emergency power
sources but safety MUST come first.
On 20/01/16 07:12, Robert Bruninga via aprssig wrote:
> Emergency Power your Ham stuff on solar panels.
> Today I tested 5 different laptop power supplies to see if they would
> run on a 72 VDC solar panel.
> Yes, every one of them would work until the load exceeded the raw
> power available from the solar panel and the solar panels current
> limited voltage crashed. Most would then cycle, trying to restart
> until the load was reduced to match the power available. One though,
> would go to LOW impedance and I assume would blow a primary fuse if
> the DC source had more output.
> Note, these supplies are typical universal 100-240 VAC 47-60 Hz and
> all worked down to 72 VDC input (the max-power voltage) of the solar
> panel. One of them was picky about which polarity was applied to the
> input cord, the others didn’t care. I couldnt test at lower voltage
> because the panel voltage rapidly goes to near zero when the peak
> power point is exceeded.
> Reason for this test is the bunch of 40 Watt 72v solar panels I got
> (VOC=100v). These panels are obsolete, but any 2 modern panels in
> series will easily give several hundred watts at around 72 volts. But
> when fully loaded to the rating of the panels 500W (typical Vp of
> around 30v each, you might want three panels in series giving a full
> 500W output at around 90 volts.
> These universal supplies also work on up to 330 VDC input too.
> So, the best tap point on your home solar panels is around 300 VDC
> (typicaly the mid point of a string of solar panels oprating up to 600
> VDC). These laptop supplies also work just fine on 300 VDC input too
> (remember 240 VAC peaks at 330 VDC). Taping into your solar array at
> around 300 VDC can deliver almost 1500W from a solar array. The
> problem is that most of what you need during a power outage do not use
> universal switching supplies, but need 60 Hz power (Well pump,
> refrigerator, etc). But for modern electronics with universal
> supplies, you’d have more power than you need forever.
> Some added detail is on this web page:
> Bob, WB4APR
> aprssig mailing list
> aprssig at tapr.org
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