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suggestions for garage door?

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Posted by danny burstein on October 27, 2009, 6:14 am
I've got a neighbor, kind of.., who has a car garage with an
overhead door. No electric lines to it, so the door has to
be lifted manually.

Even with decent springs and counterweighting it's a big pain.

Running electricity to it would be a big pain and expense, so I
was thinking of a solar solution.

I've measured my own garage which does have an electric opener.
There's a steady background draw of 3 watts for the controls
and the safety "electric eye" at the door bottom. When the motor
is running it pulls about 600 watts for the 10 second cycle.

So I figure... if we take a reasonable worst case scenario
it'll get run through 5 cycles/day.

Power usage:
a: 3 watts times 24 hours         => 0.072 kw-hr/day
b: 600 watts times (10*2*5) =     60 kw-sec /day
    ->                 => 0.041 kw-hr/day

            total:    0.11 kw-hr/day (110 watt-hr)

So far so good. If my math is right... then a 35 watt panel,
which back of envelope would get me 140 watt-hr/day (based
on getting the equiv. of 4 hours of direct sunlight), so I'd
have a bit to spare for inefficiencies and to keep the battery
charged on cloudy days or if the door gets used more.

(And if I can kill off the standby draw, even better).

The big problem is that overhead motor pulls that 600 watts,
with probably two or three times that at start up. Which
means using a big inverter...

But given the cost of running an electric line, this still
looks like a decent alternative.

Before I pull my hair out on this, has anyone had experience
and could offer a suggestion or two?

The biggest question, I guess, would be finding a DC motor
that would be usable in a garage lift assembly... The big
advantage is it would eliminate the need for the inverter.


Knowledge may be power, but communications is the key
[to foil spammers, my address has been double rot-13 encoded]

Posted by ghio on October 27, 2009, 10:54 am

=> 0.041 kw-hr/day

An electric wheelchair motor springs to mind.

Posted by Ecnerwal on October 27, 2009, 2:04 pm

...Then it's not set up right. Get a competent tech to set it up (or
replace it with something that has proper running gear.) I have a 10x10
foot 2 inch thick insulated door (a hefty item), and it's trivial to
pull up and down manually - which I've been doing for 5-1/2 years
without even needing adjustments since the initial setup.

Cats, coffee, chocolate...vices to live by

Posted by AES on October 27, 2009, 3:03 pm

I knew a semi-crazy handyman once who had cobbled together a garage door
counterweighted by a coupled of big rectangular buckets or water tanks
hung on a cable and pulley setup.  When door was down and latched,
buckets were up, and a water pipe and valve arrangement filled 'em with
water.  Release latch, buckets came down, door went up.  When door
reached the up and latched position, buckets came to rest on a pad with
a upright bar that pushed open a spring-loaded valve in the bottom of
the bucket.; water went to a nearby flower bed.

Now all you need is enough power to automate this (and drive a small
pump, if you haven't got ordinary residential water pressure).

Posted by T. Keating on October 27, 2009, 7:57 pm
 On Tue, 27 Oct 2009 06:14:50 +0000 (UTC), danny burstein

Purchase a garage door opener with a battery backup and just power via
a much larger +12 volt battery charged via a small solar panel..


or google
"battery backup garage door opener"

see above..  stick with a much simpler AC/DC system and power it via
DC only.. .

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