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I wanted to share with you guys what we've done with one of our main sites.

Unfortunately the mountain tops needed for good coverage are to far away from utility power to justify the construction cost of power lines.

Our trial site consists of of 6 rockets, 3 NBM5, and a mikrotik AC, about 80watts in total.

We have two battery banks which consist of two 12v AGM batteries, and eight GC2 6v batteries. We run 12volt banks, and for a couple of reasons. 1) it is much easier to find auto style parts and accessories if needed. 2) if we should have a power issue we can jump and charge the bank from a truck.

For charging we have 430 watts of solar and a 400watt 3 phase wind turbine.

Now keep in mind we're in Wyoming where during the winter we have a couple of months with average highs around 35f and lows at night are possible to the -30s and about 7 hours of good sun light. We also get a fair amount of wind. Honestly I get more from the wind then the sun.

The charge controller we use has a divert load resister (basically a heating coil). The plus side to that is when the banks are charged we generate some heat from the excess power. This helps keep the building warmer. It rarely drops below freezing inside the building. In the last two years we haven't had the inside temperature of the building drop below 20f, that was on a real cold night about -32 after a long week of highs not above 10f.

The battery banks, this is where we get creative. We use a RB750UP as an automation controller. I've wrote several scripts that control different functions.

We use a pair of relays (redundant) that allows us the RB to switch between the two banks. We use the AGM bank 90% of the time, and when the voltage on that bank gets low the RB automatically switches the load to the GC2 bank. Once we start charging and the voltage reaches a certain point (near full charge) we switch the load back to the AGM bank. The AGM batteries are much more durable then the G2 but they lack the true deep-cycle of the GC2s. By using the AGMs for the daily cycling and reserving the GC2s for the extended use we extend battery life a great deal and minimize maintenance.

We have another relay setup that allows us to remotely feather the wind turbine.

We also use the RB to power off our second backhaul during non-peak hours. But we're able to build some logic into the process and only turn it off if we're running on the 2nd battery bank and it automatically restarts it if traffic reaches certain thresholds.

We also use the RB to remotely activate a tower locate strobe. This was added to help the installers find the tower after sundown or during fog or poor visibility. Of corse we could do this with any poe port, but that's what the RB was intended for

I thought I'd share that because I'm curious to know if anyone else does anything similar.

What size are your batteries? I had a solar site with two NanoBridgeM5s and really had trouble keeping it up in the winter. I think we only had 100amps of battery power and a 250watt panel though, so having the added wind and solar I'm sure would have helped.

The GC2's are 230AH using the c20 rating. The AGMs are 170RC which translates to 70AH using the c20 rating. That makes our AGM bank 140AH and the GC2 bank 920AH.

Typically we don't see a NBM5 take more than 6watts. On sites where we only have two radios we don't use a switch or router and connect the two in crossover and in a number of cases we run them directly off 12v to avoid the inefficiency in up-converting. We've been able to get away with this on cable runs of 50feet or less and I usually use cat6.

I like to plan new sites with 7 days of battery reserve without any charge and the solar with 6 times the load amount.

This site has changed since it was first started and we don't entirely meet my norms but it's been ok. When we started the site it was vastly different. We had 20 watts of load, 290watts of solar, no wind and two weeks of battery.

I nearby friendly wISP has a solar site that we (we help each other for actual days off...) have trouble keeping charged in winter. Have a 400W turbine and a 200W of solar in 6x 220AH batteries. End up driving out into the middle of nowhere to charge the batteries up because the wind dies down to nothing and the panels get a little frost on them and efficiency drops to nil. Get 3 days out of the batteries, but can't get enough juice in to charge them in the winter sun. Start speed on the turbine is an issue, needs like 7-8mph wind to start and sometime there are days with 4-5mph winds :/

Like LRL, using a routerboard for voltage monitoring etc. Planning to switching that out for a arduino or beagleboard based system for <1w and adding a turbine with very low start speed.

Here's a suggestion for the panel frost ups. RainX...

OK... so 1,000AH of battery backup power. I'm paying about $400 per 100AH of battery, which makes a site like this -- in batteries alone -- cost me 4k!!!!

Do you have a cheaper source for good batteries?

I pickup our GC2s from Sam's club or Costco. They're just under $100 each and we need two for a 12 volt series. The AGMs i shop around, so far Battery Systems or Autozone are the cheapest. The AGMs cost us about $200 each. We have about $1500 in batteries for this site.

AGM is more reliable, they don't ruin if they freeze, and are completely maintenance free. The flooded GC2s are really a deep cycle battery but require watering and will freeze and die. We make one planned trip to the site a year to clean, inspect, and water the batteries.

To run AC to the site was 180K for us, and I quickly decided I could by a whole lot of batteries and panels for that.

build a house there lol, then you can't be charged for the transformer or line costs, just poles ;) A trailer house and a few poles is certainly under the $180k!!!

LOL Not sure BLM would go for that, but i love the suggestion.

rebelwireless wrote:build a house there lol, then you can't be charged for the transformer or line costs, just poles ;) A trailer house and a few poles is certainly under the $180k!!!

Wait.... how does this work? I've had people not put homes in some places because the cost to run power there was going to be too expensive.