Many of them have integrated heaters.
Sealed lifepo4 batteries should only be used at the nameplate voltage 12v
for example, some will support up to four in series for a 48 volt
configuration but it's a hack job to do it that way.
If you need 400v at 100ah you will need 110 qty of 100ah cells and a
compatible BMS.
On Thu, Aug 17, 2023, 1:51 PM Chuck McCown via AF <af@af.afmug.com> wrote:
> My electric car loses significant range at temps below 35F and as a double
> whammy, will not accept a full charge at low temps either.
>
> Lead acid work at low temps but if they get too far discharged they will
> freeze. Gates Cyclons were advertised to be able to be fully charged and
> discharged when frozen.
>
> *From:* Mathew Howard
> *Sent:* Thursday, August 17, 2023 2:13 PM
> *To:* AnimalFarm Microwave Users Group
> *Subject:* Re: [AFMUG] battery nerd question
>
> Yeah, temperature is the main problem I'm seeing with going to lithiums. I
> can throw an SLA battery in an unheated box at our towers and it's going to
> work good enough, even in the middle of winter, but the minimum charging
> temperature for LFP batteries is 32F, which we're going to be below for a
> good part of the year.
>
> On Thu, Aug 17, 2023 at 3:08 PM Bill Prince <part15...@gmail.com> wrote:
>
>> Things have evolved. You can get LFP batteries for "almost" the same
>> price as lead acid. Sometimes less even. They occupy less than half the
>> space as lead acid, and will last at least twice as long. There is the
>> issue of temperature sensitivity and they will need help for extremely cold
>> environments.
>>
>>
>>
>> bp
>> <part15sbs{at}gmail{dot}com>
>>
>> On 8/17/2023 12:36 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 mailto:af-boun...@af.afmug.com *On Behalf Of *Mathew Howard
>> *Sent:* Thursday, August 17, 2023 10:51 AM
>> *To:* AnimalFarm Microwave Users Group mailto: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] *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?
>>
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