We are at 39 _but_ the snowfall this winter was epic. Rivaling
Chucks... We aren't on tippytops but with high panel angles and decent
breaks in the coverage we only had to clear panels out a few times with
the tracked ranger... Still got stuck a few times requiring one rescue
aid.... We did have to clear out the area beneath the panels like five
times.. but shaping the gap encouraged scouring that minimized visits.
only one site out of 6 required generator service for one day. Way
better than 16 when we ran gennies at 3 sites for 1.5 months on and off..
On 8/16/23 3:30 PM, [email protected] wrote:
I end up closer to Chuck’s estimate. In Southern or Central NY State
I’m 2 degrees north of Salt Lake City. 42N
What’s your latitude?
*From:* AF <[email protected]> *On Behalf Of *Mathew Howard
*Sent:* Wednesday, August 16, 2023 4:11 PM
*To:* AnimalFarm Microwave Users Group <[email protected]>
*Subject:* Re: [AFMUG] battery nerd question
Yeah, that's what I'd do in a difficult to access location. I did a
site like that here (Wisconsin) with 200 watts of panel (I think the
actual load is around 15 watts, so a bit more than 10x), and ~4kwh of
battery. It had some issues in January a couple years, but I
attributed that more to using cheap flooded deep cycles, rather than
not enough capacity. With AGMs, it's gotten through the last couple of
winters without issues. 4kwh of AGMs can be had for around $800, last
I checked. Probably looking at closer to $1500 when you add in
enclosures and mounts, but some of that is replacing parts that are
needed with AC power anyway (smaller enclosure, backup batteries,
power supply), so that offsets it a bit.
On Wed, Aug 16, 2023 at 2:50 PM Chuck McCown via AF <[email protected]>
wrote:
Using my historical rules of thumb for off grid, snowed in
mountain top location for a 20 watt load I would do the following
that has never failed me:
Load X 20 so 400 watts of panel. So less than $200 these days.
2 weeks of battery autonomy.
20 x 24 x 14= 6720 watt hours. $2K of batts
Plus enclosures, mounts, charge controllers.
$2500 and it will never go down in the winter. At my Utah
latitude on top of Utah mountains.
*From:*Mathew Howard
*Sent:*Wednesday, August 16, 2023 1:07 PM
*To:*AnimalFarm Microwave Users Group
*Subject:*Re: [AFMUG] battery nerd question
It depends on how much stuff you're trying to run. A minimal
micropop can be done with less than 20 watts of load (single AP
and backhaul). I can put together a solar setup for around $1000
that will power that.
On Tue, Aug 15, 2023 at 12:50 PM <[email protected]> wrote:
I can save you the suspense. If you have access to electric
that’ll be cheaper than solar. The problem is the need to run
24/7. You have to design around the December-January months.
I’m in NY State, and at our latitude we only get a few hours
of average production per day during those months. And
obviously if it’s snowing for a week you need to be able to
ride through that on mostly battery power. Even with a modest
load it takes a silly amount of panels and batteries to stay
up 24/7 in the winter. More than you’d ever be allowed to put
on a utility pole.
Talk to your electric co about the smallest service you can
get. Explain what you’re trying to do and that your max load
is very low.
NYSEG normally doesn’t do less than 100A, but they made an
exception and let us do 60A. You need a meter can, a service
rated panel, a conduit up the pole and a weatherhead. Then
you either have an outdoor outlet, or have an outlet inside
your enclosure. You’ll want the smallest service they’ll let
you do because of the wire size on the service cable. A 20A
(if they’d allow it) would only need a 12/3 with ground, and
that’s up to 4800 Watts (240x20) so it’s still more than you’d
ever need. A 12/3 is way cheaper than a 100A service
entrance cable.
My figure is 8 years old, and obviously there’s been inflation
since then, but I went to the same contractor who does
electric installs for the cable company and they quoted me
about $1000. Even if it’s 3x that for you today you’d still
never beat that with a solar installation even if they’d let
you do it. And I’m not some knee-jerk anti-solar lunatic, I’m
just saying I’ve run the numbers and it doesn’t add up.
People do it when they’re off grid, or when the electric
service is unreliable in the area, or sometimes just for the
PR/marketing power of being “solar powered”. Those are all
fine reasons, but doing it for cost savings isn’t going to
work out.
-Adam
*From:*AF <[email protected]> *On Behalf Of *Steve Jones
*Sent:* Tuesday, August 15, 2023 10:27 AM
*To:* AnimalFarm Microwave Users Group <[email protected]>
*Subject:* Re: [AFMUG] battery nerd question
we have a dozen or so, but are looking at pole mount micropops
(our own poles). We are losing a grain elevator site because
they decommissioned the elevator and theres no real options
for the customers in some of the areas. Im just trying to get
to something we can get solar power with enough battery to
last through overcast. So Im calculating per battery runtimes,
then will look at number of batteries we would need to survive
vs paying for a ROW meter vs losing the customers. Just have
to get to the cost per customer to retain them and the benefit
gained per pole
On Tue, Aug 15, 2023 at 8:53 AM Brian Webster
<[email protected]> wrote:
How many of the batteries do you have? Do you need any
voltages other than the 48 volts? If you have 4 batteries
and only need 48 volts then wire them in series and not
have to deal with the converter.
Thank you,
Brian Webster
*From:*AF [mailto:[email protected]
<mailto:[email protected]>] *On Behalf Of
*[email protected]
*Sent:* Tuesday, August 15, 2023 6:59 AM
*To:* 'AnimalFarm Microwave Users Group'
*Subject:* Re: [AFMUG] battery nerd question
*You’re around C/30 which should be on the high end /of
capacity/.
Lower load usually means a little extra capacity out of
the battery. I realized that sentence might have been
ambiguous.
*From:*[email protected] <[email protected]>
*Sent:* Tuesday, August 15, 2023 6:56 AM
*To:* 'AnimalFarm Microwave Users Group' <[email protected]>
*Subject:* RE: [AFMUG] battery nerd question
You can do the whole thing in Watts.
12V * 150ah = 1800 Watt-hours
1800Wh / 50W = 36 hours
If they’re telling me 95% efficiency, I’d assume 50W out
needs 53W in (50 / 0.95).
There’s usually an efficiency curve for the device based
on load and temperature so it wouldn’t be 95% in all
circumstances. Your system should be drawing less than 5A
off the battery, and if your multimeter has a 10A fuse
like most do, then you could put the meter in line and
actually measure the amperage before and after the
converter. Then you’d know for sure.
And the battery’s total capacity will have a curve based
on C-rate so there’s some variability there too. Usually
it lasts longer when you’re drawing lower amperage.
You’re around C/30 which should be on the high end.
Age and maintenance of the battery affect runtime as
well. If I want 6 hours of runtime then I plan Ah for 12
hours runtime. When my batteries are halfway toasted I’m
still getting useful life out of them.
*From:*AF <[email protected]> *On Behalf Of *Steve Jones
*Sent:* Monday, August 14, 2023 9:57 PM
*To:* AnimalFarm Microwave Users Group <[email protected]>
*Subject:* [AFMUG] battery nerd question
Just trying to cipher runtimes
I have on hand 150ah 12 volt batteries, so thats what id
be looking to use.
Excluding the conversion loss of a 12v to 48v step up
converter is the math correct here?
12v 150ah=1800 watt hours
1800 watt hours at 48v = 37.5ah
50 watts of radio running 48v = 1.04 amps
37.5ah @ 1.04 amps = 32.77 hours runtime
does a step up that claims 95% efficiency mean 95% of the
watt hours?
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