Way cheaper to use lifepo4 now than using telecom lead acid if you look at the whole picture
On Thu, Aug 17, 2023, 1:03 PM Mathew Howard <mhoward...@gmail.com> wrote: > LiFePO4. There are a few different ways you can go with that though. You > can get something like these: > https://www.18650batterystore.com/products/eve-lf280k which I think > actually comes out slightly cheaper than SLA/AGM, but then you need a > separate BMS, or you can get something like this: > https://www.ebay.com/itm/166234057827 which is made to be a drop in > replacement for lead acids, and has a built in BMS. > > > On Thu, Aug 17, 2023 at 2:37 PM <dmmoff...@gmail.com> wrote: > >> Ooh What lithium batteries are we talking about? >> >> Last time I checked (a number of years ago), it was around 5x the $/Wh to >> buy Lithium. >> >> >> >> >> >> *From:* AF <af-boun...@af.afmug.com> *On Behalf Of *Mathew Howard >> *Sent:* Thursday, August 17, 2023 10:51 AM >> *To:* AnimalFarm Microwave Users Group <af@af.afmug.com> >> *Subject:* Re: [AFMUG] battery nerd question >> >> >> >> 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 <dmmoff...@gmail.com> 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 <af-boun...@af.afmug.com> *On Behalf Of *Mathew Howard >> *Sent:* Wednesday, August 16, 2023 5:01 PM >> *To:* AnimalFarm Microwave Users Group <af@af.afmug.com> >> *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 <dmmoff...@gmail.com> 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 <af-boun...@af.afmug.com> *On Behalf Of *Mathew Howard >> *Sent:* Wednesday, August 16, 2023 4:11 PM >> *To:* AnimalFarm Microwave Users Group <af@af.afmug.com> >> *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 <af@af.afmug.com> >> 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 <dmmoff...@gmail.com> 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 <af-boun...@af.afmug.com> *On Behalf Of *Steve Jones >> *Sent:* Tuesday, August 15, 2023 10:27 AM >> *To:* AnimalFarm Microwave Users Group <af@af.afmug.com> >> *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 <i...@wirelessmapping.com> >> 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:af-boun...@af.afmug.com <af-boun...@af.afmug.com>] *On >> Behalf Of *dmmoff...@gmail.com >> *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:* dmmoff...@gmail.com <dmmoff...@gmail.com> >> *Sent:* Tuesday, August 15, 2023 6:56 AM >> *To:* 'AnimalFarm Microwave Users Group' <af@af.afmug.com> >> *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 <af-boun...@af.afmug.com> *On Behalf Of *Steve Jones >> *Sent:* Monday, August 14, 2023 9:57 PM >> *To:* AnimalFarm Microwave Users Group <af@af.afmug.com> >> *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 >> AF@af.afmug.com >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> >> -- >> AF mailing list >> AF@af.afmug.com >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> >> ------------------------------ >> >> -- >> AF mailing list >> AF@af.afmug.com >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> >> -- >> AF mailing list >> AF@af.afmug.com >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> >> -- >> AF mailing list >> AF@af.afmug.com >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> >> -- >> AF mailing list >> AF@af.afmug.com >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> >> -- >> AF mailing list >> AF@af.afmug.com >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> > -- > AF mailing list > AF@af.afmug.com > http://af.afmug.com/mailman/listinfo/af_af.afmug.com >
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