Solar power battery system for WRT54GS

I have need to set up a bridge in a location visible to myself and a
secondary source. No AC power is available. Where would I go to buy
'Solar power systems' with batteries and the like for a WRT54GS?

What price should I expect to pay? I'm trying to find out if it's
financially viable. If so, I'll be buying and installing in the next
two weeks.

<(E-Mail Removed)> wrote in message
news:(E-Mail Removed) ups.com...
>I have need to set up a bridge in a location visible to myself and a
> secondary source. No AC power is available. Where would I go to buy
> 'Solar power systems' with batteries and the like for a WRT54GS?
>
> What price should I expect to pay? I'm trying to find out if it's
> financially viable. If so, I'll be buying and installing in the next
> two weeks.
>
You can buy solar panels and batteries from loads of online retailers. You
just need to consider what current is drawn over the hours of darkness -
then get a battery big enough. Also get a solar panel big enough to give
the required charge and actually run the router during the day.
Then work out your figures on whatever you consider it to be financialy
viable against.

(E-Mail Removed) wrote:
>I have need to set up a bridge in a location visible to myself and a
>secondary source. No AC power is available. Where would I go to buy
>'Solar power systems' with batteries and the like for a WRT54GS?

What does it draw at 13.8 volts? IIRC my WAP54G is just a few watts.
Depending on where you are installing it, and your insolation
available, the calculation is pretty simple:

Find the power consumption, call it 5 watts just to have something to
talk about (confirm this before buying anything).

5 watts times 24 hours per day is 120 watt-hours.

Solar panels are rated at peak output at a nominal one sun input
(1000W/M^2), and most places in the US get between 4 and 5 "peak sun
hours" per day.

Divide 120 watt-hours by 4 to get 30 watts of solar panel. You want
to upsize a bit to cover recharging after extended outages, so get at
least 40 watts. http://mrsolar.com/ has 40-watt panels for $285,
which probably isn't awful.

How many days of battery backup do you want? Since you are only using
10 amp-hours per day, and you don't want to use more than half of your
battery capacity, you need between 50 and 100 amp-hours.
http://mrsolar.com/ has a UB27 for $125 that looks OK.

You also need a 5 amp or better charge controller, that's probably an
ASC 12/4 for $44. Check to be sure it can be set up for charging gell
cells.

If you can get to the site and top off the battery water occasionally,
you could save some money by using a pair of golf cart batteries for
$100 and no charge regulator. HydroCaps can keep the need for battery
maintenance down in this situation, but they add $50 to your initial
outlay.

Call it $500 plus or minus (do you need a housing for your WRT?
External antennas? Do you need cabinets or boxes to put all this
stuff in? Is it subject to very high or low temperatures? Vandalism?
Is there anything else you haven't told us?)

Don't forget $50-$75 for the WRT, plus whatever you are using as
endpoints...

>I have need to set up a bridge in a location visible to myself and a
> secondary source. No AC power is available. Where would I go to buy
> 'Solar power systems' with batteries and the like for a WRT54GS?
>
> What price should I expect to pay? I'm trying to find out if it's
> financially viable. If so, I'll be buying and installing in the next
> two weeks.
>

Here are some discussions you would be interested in:
http://www.wirelessforums.org/hardwa...dvice-312.html

I like this one:
http://www.crc.net.nz/img/solar-repeater.jpg

(E-Mail Removed) wrote:
> I have need to set up a bridge in a location visible to myself and a
> secondary source. No AC power is available. Where would I go to buy
> 'Solar power systems' with batteries and the like for a WRT54GS?
>
> What price should I expect to pay? I'm trying to find out if it's
> financially viable. If so, I'll be buying and installing in the next
> two weeks.

You can probably set it up for around $350-400, depending on how you're
planning to mount the panel and the battery. Is it an outdoor location?

That unit draws around 6 watts, so figure around 50 watts to account for
the panel not being aimed at the sun all the time, plus being able to
both operate the unit and charge the battery at the same time.

See "http://affordable-solar.com/kyocera-kc50.html"

Buy a sealed lead acid battery and a controller

See
"http://www.allelectronics.com/cgi-bin/item/SCN-2/search/DC_VOLTAGE_CONTROLLER_FOR_SOLAR_PANEL_.html"
"http://www.allelectronics.com/cgi-bin/item/GC-1214/160400/12_VOLT_12_AH_RECHARGEABLE_BATTERY_.html"

A 12 volt/12 amp hour battery (144W) would be good, which will give you
some buffer for cloudy days.


Too bad you can't buy a surplus roadside call box somewhere.

I couldn't find a manual on-line for this device, but I have run a
Dlink DWL-900AP+ wireless on batteries. The factory supplied power
supply is a 5V switch-mode wallwart. For simplicity, I built my
portable device to run from 6 C cell nicads, then used a low drop-out
voltage regulator that I built using a Texas Instruments chip. [If
relevant, I can dig up the number.]

If you are going to use an off the shelf 12V solar system, you will
need to build a DC/DC converter to reach 5V, most likely a buck
configuration. If you used a LDO linear regulator from a 12V supply,
more than half the power would be used in just dropping the voltage.

It would be more work on the solar cell side of the task, but I would
set up a 6V system using a gell cell, then build a 5V regulator using a
low drop out chip. I specify low drop out in that these devices use
PMOS pass fets rather than a PNP, so they are very efficient, not to
mention more stable. [The PNP in those cheap bipolar regulators sits
near saturation, which leads to much power wasted in the base driver
current, plus difficult circuitry to keep the PNP from entering
saturation. It's ugly.] The skill required to build a switcher is an
order of magnitude higher, both in circuit design and in layout
(construction). The low drop out linear regulator is just the chip and
a few capacitors. You would need basic soldering skills, but not much
beyond that.

I know very little about solar cells themselves. My guess here is you
would assemble enough to float the gell cell, and use a Schokty diode
to prevent back flow when light is no longer shining on the cells.

Your first step would be to determine how much current your router
draws. The wall wart is often overated, that is the router draws much
less current than the wall wart could put out. I simply got a bench
supply, built a cable, and measured the current while the box was
operating. Once you know the current required, you can narrow down the
LDO regulator choices. The maximum voltage you will get out of the
solar cell and the current requirement of the router will determine the
power dissipation required by the LDO. If you go this route, just do
another post and I can pick the part. Texas Instruments has the most
product in the high power LDO market, so that is where I would look.

(E-Mail Removed) wrote:
> I have need to set up a bridge in a location visible to myself and a
> secondary source. No AC power is available. Where would I go to buy
> 'Solar power systems' with batteries and the like for a WRT54GS?
>
> What price should I expect to pay? I'm trying to find out if it's
> financially viable. If so, I'll be buying and installing in the next
> two weeks.

William P.N. Smith wrote:

> How many days of battery backup do you want? Since you are only using
> 10 amp-hours per day, and you don't want to use more than half of your
> battery capacity, you need between 50 and 100 amp-hours.
> http://mrsolar.com/ has a UB27 for $125 that looks OK.
>
> You also need a 5 amp or better charge controller, that's probably an
> ASC 12/4 for $44. Check to be sure it can be set up for charging gell
> cells.

Now, I know you hang out in the homepower group, William, so you should
realize those numbers don't compute.

If you want a 50amp-hour battery, you really need to be able to get a 10amp
charge into it. If you're charging a 50-100amp-hour battery with a 5amp
charge controller, you run a risk of never really getting a full charge
into your battery, and shortening its life.
--
derek

(E-Mail Removed) wrote:
> I couldn't find a manual on-line for this device, but I have run a
> Dlink DWL-900AP+ wireless on batteries. The factory supplied power
> supply is a 5V switch-mode wallwart. For simplicity, I built my
> portable device to run from 6 C cell nicads, then used a low drop-out
> voltage regulator that I built using a Texas Instruments chip. [If
> relevant, I can dig up the number.]
>
> If you are going to use an off the shelf 12V solar system, you will
> need to build a DC/DC converter to reach 5V, most likely a buck
> configuration.

Not for the WRT54GS. 12 volts is fine.

SMS wrote:

> A 12 volt/12 amp hour battery (144W) would be good, which will give you
> some buffer for cloudy days.

Oops, this isn't enough, my mistake. Use a 55AH battery
("http://zbattery.com/zbattery/mpl55-12.html")

Like I said, I couldn't find a manual. However, it is uses a 12V wall
wart, what current does it draw?

If a repeater would do the job (rather than a bridge), SMC has some
boxes that run off of 5V @1A.
http://www.smc.com/files/AY%5CDS_WEBT_G.pdf
The product is described as a bridge, but it lists repeater in the
modes. I'm not much for the details of networking, but I know there is
a difference.

The big expense in this project will be the solar cells, so you want to
get as low of power on the electronics as possible.


SMS wrote:
> (E-Mail Removed) wrote:
> > I couldn't find a manual on-line for this device, but I have run a
> > Dlink DWL-900AP+ wireless on batteries. The factory supplied power
> > supply is a 5V switch-mode wallwart. For simplicity, I built my
> > portable device to run from 6 C cell nicads, then used a low drop-out
> > voltage regulator that I built using a Texas Instruments chip. [If
> > relevant, I can dig up the number.]
> >
> > If you are going to use an off the shelf 12V solar system, you will
> > need to build a DC/DC converter to reach 5V, most likely a buck
> > configuration.
>
> Not for the WRT54GS. 12 volts is fine.