Well, right. It doesn't scale well, because battery costs and space requirements will quickly become a problem. Batteries don't last forever, so you have to factor in replacement costs too, which will be a significant ongoing cost for a larger system. I'm pretty sure that lithium batteries would be cheaper long term now, since they should have a lot longer life span and the initial cost isn't a lot higher, but then heating is required, which means you need more power.
On Wed, Aug 16, 2023 at 7:02 PM <[email protected]> wrote: > That’s building strictly for a 20W load though. Building for a tiny load > does make the costs easier. But if you wanted a second AP, bigger > backhaul, or anything else you can’t do it without growing the whole power > system proportionally. > > > > Steve was talking a 50W load today. The real high end hardware now is > using a lot of signal processing either to reassemble useful data out of > garbage or for beam steering, or both. So you end up needing 100-150W for > an AP. You’d be hard pressed to find a licensed backhaul under 35W, and > most of them are 50W+. We could say we won’t deploy that equipment….but > building for a 20W load takes the choice away. > > > > A 20A 240v circuit is 4800W. Or a 20A 120V circuit is 2400W. Even 2400W > would power almost any WISP deployment. Building solar to handle any load > you might have is expensive, and building for only low power handcuffs > you. > > You do your thing your way, no judgement. If it’s working for you then > it’s good, but I can’t see myself going that direction. > > > > -Adam > > > > > > > > *From:* AF <[email protected]> *On Behalf Of *Mathew Howard > *Sent:* Wednesday, August 16, 2023 5:01 PM > *To:* AnimalFarm Microwave Users Group <[email protected]> > *Subject:* Re: [AFMUG] battery nerd question > > > > I'm at about the same latitude as you. My experience is that having extra > battery capacity is more helpful than oversizing the solar panels, so I'd > probably go with Chuck's numbers for batteries if I was putting something > together now, and solar panels are cheap now anyway, so figure 400 watts > (if mounting space allows for it, which could be an issue if we're trying > to fit it on a pole). > > > > A quick check on Amazon shows 100ah SLA batteries for $160, so 6 of those > would give me 7200 watt hours, for just under $1k. At $1500 (which is > mostly just adjusting battery and panel sizes from where I started at $1k), > I'm right in line with Chuck's estimate, aside from the battery costs. > > > > On Wed, Aug 16, 2023 at 3:33 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] <[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? > > -- > AF mailing list > [email protected] > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > > -- > AF mailing list > [email protected] > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > > ------------------------------ > > -- > AF mailing list > [email protected] > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > > -- > AF mailing list > [email protected] > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > > -- > AF mailing list > [email protected] > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > > -- > AF mailing list > [email protected] > http://af.afmug.com/mailman/listinfo/af_af.afmug.com >
-- AF mailing list [email protected] http://af.afmug.com/mailman/listinfo/af_af.afmug.com
