The solution is a 72Ah $60 deep cycle marine battery from
Costco, a 2A
battery maintainer and a few relays and electronics. The
Linksys WRT54G
power requirements are well documented and feeding 12v
from a marine battery would be fine. The dish however had a 24V
power supply and since it'd be very hard to replace I didn't want
to feed it with a lower voltage. Luckily I found a
this 12v
to 24v converter which worked a treat.
My original plan was to just run the charger into the battery
and run the power off the battery at the same time. I ran like this
for about a week and monitored the voltage on the battery and it
was dropping. It's understandable that the 2A charger couldn't
supply enough power to the router, dish AND charge the battery, so
I put back in the old wall warts to power everything and went back
to the drawing board.
I got 2 12V relays from Radio Shack and set it up so that when
the router wall wart was powered all power to the dish and router
came from the outlets. As soon as the power goes out the power from
the battery is used. It works well. During the power switch the
dish and router reset which is fine by me, I guess I could fix that
with a large capacitor or something. and the 12V to 24V converter
is always on the battery which is sub optimal but not awful.
I wired it all up such that I can put it in and out of the
system easily. This allows me to bring it home to work on and
install it easily without bothering my neighbors too much. I meant
to get a picture of it installed, but they came home and I didn't
want to bother them anymore than I already had. I used Anderson PowerPole
connectors for the battery connection and I can see why radio hams
like them so much, they're so easy to work with, I'm now a big
fan.
I haven't load tested the system yet to see how long the
battery can keep everything running during an extended outage. I
also don't hold much hope that the 2A charger will get the battery
back to charged in a super quick time, but it's already proven it
can recharge it after about a week.
I do plan to add serial ports to my
WRT54G and then add a
1wire reader to read a DS2438
voltage monitor to monitor the voltage of the battery remotely.
That will be a whole other blog post if I ever get it to work. Once
I do get it working I'll feel more comfortable about turning off
the power so I can monitor the battery voltage and not let it get
too low. I suspect it might work for up to a week with no power
input at all.
Now I want to have a similar system at home in the AV closet
where my Ethernet switches and home wireless router are.
I'm planning on getting a
RigRunner 4004 USB and running 12 gauge wire from the vented
wood-box with the battery in it into the AV closet where I'll use
an old laptop battery as an alternate 70W 12V power
supply. the USB ports will also help me charge my phone during an
extended power outage.