Hybrid Car – More Fun with Less Gas

sug's for very low maint. low usage charger/batter system?

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Posted by danny burstein on May 16, 2011, 8:27 pm
 
Thanks to folk here a couple of years ago, I learned about
a bunch of mainstream, off-the-shelf, door openers that are
using 12VDC battery "backup", with the motors themselves
running at 12vdc.

The price premium is only a hundred or so dollars above
a standard unit, and that would be a lot cheaper than
running 120vac to the building.

I'm figuring on replacing their standard 12V battery with
a larger capacity unit, and keeping it charged up with a
solar panel. Since the opener only activates for a minute
or so (if even that) and only a few times/day, the numbers
should make sense.

My biggest concern is the low maintenance issue. It's got to
just be able to sit there with no one tweaking it for a
couple of years at a time. (replacing the battery every
five years or so would work).

In other words, I can't have it overcharging... or for
that matter, stopping charge when the battery's too low.

Suggestions?

Thanks.


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

Posted by Mauried on May 18, 2011, 3:35 am
 
On Mon, 16 May 2011 20:27:46 +0000 (UTC), danny burstein


Any normal MPPT type solar charge controller will do what you want.
The only issue is how much power per day will the opener use and can
the Solar panel keep up in the middle of winter if there are a series
of cloudy days.


Posted by danny burstein on May 18, 2011, 4:31 am
 

thanks. I've measured a "regular" garage opener at about 500 watts
for 30 seconds. (I don't have one of these 12 v ones around...)

So if they pull the same wattege, and let's guess at ten uses/day,
that's...  30 seconds times 2 (up and down) = one minute.
then times ten => ten minutes.

power draw of 0.5 kw, so that's 5 kw-min, divide by 60
which gives us a bit under 100 watt-hours/day.

rule of thumb... take peak output and multiply by 3 (northern US)
or 4 (southern) to get daily total...

so a 50 watt panel would give 150 watt-hrs/day. On sunny days
that's more than enough, and on cloudy days we might get
fifty or so... and the battery could manage for a week's
worth easy.

In other words, the numbers pretty much do work out.

Thanks



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

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