Eric Fletcher's posts

Posted by Eric Fletcher on Jun 5, 2009 11:08 am

#1 -  Renewable Energy > RE General Discussion > Re: Power needed for remote wireless signal repeater
Yes, I guess you nailed it David: seeing it through is the goal now!

Like a lot of this project, the first approach to the "problems" has been to just jump in and try to figure it out on the fly. Not very scientific, but with tips and resources on the web -- like this forum in fact -- we've been able to make decent progress.

Determining the BTUs is complicated because the characteristics of my insulated container are not well known. I have been recording inside/outside extremes since last October, but opening the door in -25C skews the minimum pretty rapidly! Having a much better record of the temperatures will help, so I'll be installing a weather logger.

The tower is now becoming a bit of a test bed for some other ideas too, so stay tuned...

Since you guys have been a part of helping to get it to its current state, here's a link to what it looks like (at least as of winter; the page will be updated when we have the wind generator up on it):

The bear shown near the end has been back, but now the tower is just part of the scenery so I guess he isn't as interested!

Posted by Eric Fletcher on Jun 4, 2009 01:41 am

#2 -  Renewable Energy > RE General Discussion > Re: Power needed for remote wireless signal repeater
The problem I face is the cold though Ken: by late November, the battery chamber was below -20C at night, and with almost no sun and 24/7 power drain, the batteries couldn't stay charged, and dropped way below the threshold they need. They are deep cycle renewable energy batteries (made in the US even though we are in Canada) and cost ~C$275 each. By January, when we frequently dip below -30C, the batteries had dropped to 3.5VDC and nothing worked.

We have subsequently purchased a wind generator (WG), and will install it on the tower mid-June. We've had to figure out how to keep the batteries warm in winter though, and hopefully have a solution now. Once the batteries reach fully charged state, some custom electronics will divert the power coming from the WG to a radiator with some glycol and water and a 12V heater to keep the battery chamber warm. In summer the extra power can run a fan to cool it because the summer highs exceed 35C. With a 400W wind generator, I should have enough power.

Posted by Eric Fletcher on Nov 27, 2008 01:57 pm

#3 -  Renewable Energy > Technical Discussion: Other > Re: Wire Size
I came across your post and thought I'd share a link I've found useful for this sort of thing. The page has a data table with a handy calculator below it.

You mentioned elsewhere that you have a long run of #8 wire: are you running 120VAC, and do you convert it to DC at the end?


Posted by Eric Fletcher on Nov 25, 2008 11:00 pm

#4 -  Renewable Energy > RE General Discussion > Re: Power needed for remote wireless signal repeater
We are having our first real snow here tonight, and I'm astonished that I can actually get online: yesterday I had to hike up to my tower and carry the two 32kg batteries down to be charged. Luckily, I had a "spare" car battery up there already, and it seems to have sufficient power to keep me running for now. I don't look forward to having to slog through snow tomorrow to haul the other batteries up though...

Why did they drain out? Well, it seems that an 80W solar panel just can't produce enough power to both run the radios and recharge the batteries. According to the very useful Canadian govt site (, I can only expect 51-59 kWh/kW of photovoltaic potential at my location in November (vs up to 138 in July). The current setup is draining at 14.4A/day, so my two 100Ah batteries will drain in 12.9 days without sun. With only 80W, I calculate it would take 11.3 days of sun to recharge -- very unlikely here in November! A 2nd panel would reduce this to 5.3 days; better, but still on the edge.

I am intrigued by your solution though: are you running 120VAC to the tower and then using it to charge batteries for the radios? Have you had any sign of animal damage to the conduit?

About pictures and notes... if you Gmail me, I'd be happy to send you a link. To avoid bot harvesters, I won't spell it out, but the 10 characters are the initials of my first & 2nd name (EJ) followed by my surname.

Posted by Eric Fletcher on Oct 17, 2008 02:59 pm

#5 -  Renewable Energy > RE General Discussion > Re: The Manhattan Project of 2009
I certainly share your sentiments Thomas. However, no matter how many humans there are, there is no real net increase in mass; we use matter and energy to grow from nothing, and then return the matter when we die. The energy part is more of an issue though, particularly when the amount consumed by each of us has been magnified so much by the secondary energy we make use of while we are alive.

"After all, humans not only lived on Earth for thousands of years without all of the modern conveniences we take for granted today, the human race flourished without them."
Actually, we didn't really start to flourish until we figured out how to get machines to do the hard work. The population has grown exponentially since then.

In any case, unless we can figure out how EACH of us can do with a whole lot less consumption, we are going to hit a wall pretty soon. Nature has a history of solving problems by extinction or mass die-offs. Maybe the wake-up call is only going to get through to the small portion of us who manage to live through the mess we are causing...

I like the direction of the book Sherry mentions, but fear it may be too little, too late -- even if it did get the kind of attention it deserves. The real problem isn't finding substitutes for our consumption; we really do need to learn how to manage with less -- and I sure don't see any sign of that happening anytime soon.

Posted by Eric Fletcher on Oct 17, 2008 01:49 pm

#6 -  Renewable Energy > RE General Discussion > Re: Solar Power for a Fonera (Wi-Fi Access Point)
I tapped into this excellent forum a while back for much the same requirement. I had thought I would run wire to a tower for my wireless access, but that wasn't feasible.

I now have a 40' tower on a 200' cliff in the back of my property. It has 3 radios powered by a deep discharge 12V battery (~Cdn$250), which is being charged up by an 80W Sharp solar panel (~Cdn$550) running through a 30A charge controller (~Cdn130). I had some problems earlier with bears but that is behind me after building a metal-clad box ~4' off the ground for the equipment.

The tower has a 5.8GHz antenna for the back haul, plus two access points (2.4GHz and 900MHz). A bridge connects the 3 radios. Total power draw is ~300mA for each device, so ~1.2A continuous. The "wall warts" just drop the voltage to 7-14VDC so we discarded them and power the radios directly from the 12V battery. It is a good idea to install a switch to be able to shut off the power precisely and easily when you need to fiddle with the battery.

Not only do I now get good high speed service, but many of my rural neighbors are now being installed to get service too from the antennas.

I am concerned about the power draw though: we had a spell of cloudy days, and the battery dropped below 7V so the radios stopped. When the sun came out, things came back up, but 80W is evidently not enough for dismal months like November. Moreover, we will typically get down to -30°C during January, so even my heavily insulated box won't be sufficient to keep it warm enough.

I am considering adding a 2nd battery and a small wind turbine (~Cdn$650). The turbine will charge 24/7 and I think I can "dump" extra charge into a small heater if necessary.

Good luck with your AP; it sure makes a difference for those of us too far from cable or DSL.

Posted by Eric Fletcher on Sep 1, 2008 12:05 am

#7 -  Renewable Energy > RE General Discussion > Re: Power needed for remote wireless signal repeater
I thought I should update this thread... I now have a tower installed and the antennas are giving me good high speed Internet access.

It turned out that running wire was too complicated: voltage drop, cost, aesthetics -- and most troubling, liability issues. So for now, everything is running off a single 12V battery, but of course that won't last for long. We're monitoring the power drain and will add either a small wind generator or solar panels to the tower later.

Putting up the tower was a chore: a 200' near cliff (mostly 75°+ rise) meant everything goes up on someone's back. The tower parts weren't too bad, but the gas powered corer and the 18 gallons of water we needed to bore anchor holes was pretty challenging! But the view is amazing and the throughput is better than anticipated so it is worth all the hassle.

Thanks for the advice and ideas.

Posted by Eric Fletcher on Jul 13, 2008 01:01 am

#8 -  Renewable Energy > RE General Discussion > Re: Power needed for remote wireless signal repeater
Yes, the cold is an issue Dave. However, I have a tractor that sits outside and a car in an unheated garage, and both have batteries capable of enough cranking amps to start even in the coldest weather, so I was hoping that I'd be okay with this.

I've done the analysis and feel inclined to go with the wire through the woods method. The estimated cost for the solar without a camera is $863; the 515m of wire I need is $855 -- and with wire, I can power a camera. I still like a solar solution but I guess for the immediate issue, I'll go the traditional route.

Thanks for everyone's help; I've learned a lot.


Posted by Eric Fletcher on Jul 9, 2008 01:41 pm

#9 -  Renewable Energy > RE General Discussion > Re: Power needed for remote wireless signal repeater
Thanks for the response Eric. I'd tried the calculator but couldn't get it to work -- until I tried it again today with IE instead of Firefox. (In Firefox, it doesn't do any calculations and hangs up for some reason.)

Since there are no sun hour figures for where I live (Quebec, Canada), I guessed that we'd be similar to Rochester NY. With that, it looks like I could manage with a single 30 watt panel if I don't include the camera.

I can see that if the camera really does add 3600 watts per month, my panel requirement goes up to 126 watts which would add quite a bit to the cost. I'll reassess the options in that regard.

However, your followup notes that the camera would use 5 watts per hour but wouldn't it be less if the voltage is only 5V? The camera I looked at comes with one of those 120V converters but the technical specs say 5V so I assume I would be able to provide the power directly from a DC source. Is there some way to tap off just 5V from a 12V source? (This is where I feel like I'm getting over my head!)

The other item that came up from using the calculator relates to the lowest temperature the battery would experience. When I put a value of <0, the calculator displays a capacity of "NaN" but if I used 1, it displays "187" amp hrs at 12V.

Is this just a function of the calculator, or do I need special batteries to withstand very low temperatures? I assume people in places like ND or AK would encounter similar cold -- and certainly my tractor and car manage with their batteries in temperatures that go much lower than 0°F.


Posted by Eric Fletcher on Jul 8, 2008 10:55 am

#10 -  Renewable Energy > RE General Discussion > Power needed for remote wireless signal repeater
I need to provide power for a remote wireless antenna setup and am completely new at this. Here's what I know and think I need; I'd appreciate any advice.

-- 2 radios draw 400mw at 12V
-- Monitoring camera (optional) draws 5V at 1A (Linksys WVC54GCA)
-- Mean daily insolation at my location (45° 34'N): annual 4.4 kWh/m2; November worst case 2.5 kWh/m2

I would like to get the power from a solar array but am not sure how to calculate what wattage would be needed and what components I would need for the system. The radios would be on 24/7 and I would like to have sufficient power from batteries to last at least 3 days without any sun.

The site is located on a rock outcrop and weather conditions can be extreme (+40C to -40C). I can build a weatherproof container to protect batteries and electronic equipment as needed. The camera is optional in part because I'm not sure it can withstand the conditions. The site is ~600m from my house with the only other access from a wilderness park area so I would like some sort of security.

Wind is an option but I haven't got data about it for the location; however, a wind generator would be more visible and thus less secure.

Background: Although I cannot get a decent signal at my house, my property has a ridge where we were able to get a good signal from hot spots of a local wireless provider. He is willing to put up the tower and antennas if I can provide the power. This will give me high speed access and give him the ability to provide service to a number of other nearby locations.

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