Fwd: [aprssig] Emergency Power for Ham stuff

Bill Vodall wa7nwp at gmail.com
Tue Jan 19 22:49:41 PST 2016


Good info on a MPPT solar charger system.

Bill


---------- Forwarded message ----------
From: Kenneth Finnegan via aprssig <aprssig at tapr.org>
Date: Tue, Jan 19, 2016 at 5:16 PM
Subject: Re: [aprssig] Emergency Power for Ham stuff
To: TAPR APRS Mailing List <aprssig at tapr.org>


Laptop power supplies with a diode are FAR from ideal for charging
batteries. Acceptable, maybe, but let's not forget how far we are from
ideal.

I've been using the Tracer MPPT charge controllers from EP Solar for
the last few years, and I've been really happy with them:
* Their Tracer N215BN models support up to 20A of load current and 40A
of charging current at both 12V or 24V
* <$150 for their 20A model, which is a really good deal.
* Fully programmable battery profile if you want something different
than the Gel, AGM, or Flooded profiles they come with. (I've been
toying with hooking one up to a LiFe bank)
* Automatically do a "balancing" charge every few weeks
* Squeezes as much power out of the panels as possible, given the
current solar conditions
* All the settings/power readings go between the charge controller
body and the control head (part number MT-50) over RS-485/Modbus.
Convenient that the connection is via standard Ethernet cables,
awesome that you can conceivably talk to the controller using
something other than their control head.

Here's a link to the 20A model that I use at most of my solar sites:
http://www.amazon.com/gp/product/B00ZV3I3UU/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B00ZV3I3UU&linkCode=as2&tag=theli091-20&linkId=I3CHGC7WMG2WQOQO

--
Kenneth Finnegan
http://blog.thelifeofkenneth.com/

On Tue, Jan 19, 2016 at 3:30 PM, Robert Bruninga via aprssig
<aprssig at tapr.org> wrote:
>
> > Is there particular reason you're looking at powering a full blown laptop?
>
>
>
> Not a “laptop”, but a “Laptop supply” which can power all kinds of stuff and are readily available by the box full at most hamests and yard sales.
>
> Look carefully for ones at 15v which, with one diode are ideal for charging a 12v battery.  Or go ahead and use a 19v one with a simple $3 DC/DC converter to 13.8b.
>
>
>
> Bob
>
>
>
> On Tue, Jan 19, 2016 at 3:12 PM, Robert Bruninga via aprssig <aprssig at tapr.org> 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:
>
> http://aprs.org/camp-solar.html
>
>
>
> Bob, WB4APR
>
>
>
>
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>
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