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Treehouse Wiring, 12v, solar panel


By GDuncanson, Section Controls
Posted on Mon Mar 27, 2006 at 10:44:24 PM MST
Treehouse Wiring

Hi,
I've built a treehouse for my kids and would like to electrify it with 12v dc.  I hope to install a couple of 12v lights and lighter recepticles so they can use their electronic gear (I'd rather they didn't but that's another story). I already have a couple of lightly used diehard car batteries and wire. I just ordered a ICP BatterySaver 6W to maintain the batteries. The treehouse has decent southern (we're in CT) exposure and the Panel has a built-in charger protection so I think that it's pretty straighforward system. I need help with some of the details of the physical wiring. does it make sense to put a switch to flip the current from the batteries to from the panel? do I simply run the batteries in parallel and run wires to a terminal block which I then branch off to the fixtures?
Treehouse Wiring, 12v, solar panel | 11 comments (11 topical)

Re: Treehouse Wiring, 12v, solar panel (3.00 / 0) (#1)
by ghurd on Tue Mar 28, 2006 at 08:08:16 AM MST

"Panel has a built-in charger protection"
It has protection against discharging the battery backward through the panel at night.
It does not have over charge protection. That's OK, because over charging is not going to be much of a problem with a 6W panel.

"a switch to flip the current from the batteries to from the panel"
Do NOT do that. A panel with no battery will have power spikes, and dips.  It will kill the electronics. Quick.
The battery is like a shock absorber, keeping the electricity in a stable condition.

Easiest way to think about it is like 2 systems. One charges the battery, the other powers stuff.
The panel connects to the battery.
The outlets and lights connect to the battery.

It would be a great idea to have a main 10 amp fuse very near the battery Pos, and maybe another very close to the battery Neg.  Just in case.

The battery must be in a good solid case, where kids can't set a conductor on the battery, like a wrench, knife, pipe...  Kids will be kids.

Wire could be 14-2 w/g UF-B. ("Grey romex" at the store where the kid doesn't really know what he's looking at)  Plastic top staples.

Terminal blocks are a good idea. Probably inside the battery box. Kids are kids.
Remember to re-tighten the screws in a day or 2.  Ox-Gaurd (sp?) on the terminals and wire will help keep corrosion problems down.

Remind the kids to shut off the light. Games don't run from dead batteries.

Now the hard part.  Telling you 6W isn't much power at all.
The light bulbs will need to be dim and low power, 10 watt? Only one would be best.
GameBoys, etc, don't use much power.  Lights do.
There are some fluorescent lights available that have a jack for 12V power. AA battery operated, maybe at Lowe's / Home Depot. $8?  Not great, but workable. Radio Shack store can make the power wire.
Paint the inside white.

Or maybe a clear round marker light with a 6W bulb from the auto parts store.

Batteries go dead from sitting. The 6W panel is just a little more than needed to keep up.
Two batteries need twice as much power to keep from going dead from sitting.
Best to use only one battery.

Check the battery fluid levels every so often.
Check the battery state of charge every week or 2. It may need grid charged sometimes if the panel is not keeping up.  Using low batteries will ruin them in short order.
It could be worth the money to add a second panel later, depending on how the system works.

G-



Re: Treehouse Wiring, 12v, solar panel (3.00 / 0) (#3)
by GDuncanson on Tue Mar 28, 2006 at 11:48:47 AM MST

Thanks for the time and thought you put into the details.

I'm a little disappointed that I may have undersized my panel.  I assumed if 2w are enough to trickle charge a single battery, 6w ought to be enough to maintain 2 batteries. Not right?  I was hoping for some robustness if we have several rainy days in a row.

I was already planning on securing the batteries from "the things that boys can do"; by putting them each in a marine battery box and enclosing that in a wooden box with a lockable lid.

[ Parent ]



Re: Treehouse Wiring, 12v, solar panel (3.00 / 0) (#4)
by ghurd on Tue Mar 28, 2006 at 12:35:33 PM MST

No problem. Takes me longer to type. I won't even get into spelling.

The 2W Panels are only good for maintaining small, full, and unused batteries at the company's test facilities in the cloudless Sahara on a cool day.

If it's not too late or too expensive, send the ($80?) 6W back.
The 'Sportsmans Guide' or Harbor Freight have been running sales on 30 and 45W panel systems (3 of the 15W panels), for about $200, including some cool stuff like 12V CFL lights, controllers, etc.
I do not think they are great, but they would be great for your purpose.

A couple links.
Not sure if the $200 price is still valid, but it goes on sale every so often.
Not bad if you figure the cost of 2, 12V CFLs, controller, wire, etc. (Free Shipping?)
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=90599,

Some more info.
http://www.fieldlines.com/story/2006/3/2/8497/02309
http://www.fieldlines.com/story/2006/2/8/184052/7925

The 45W (3 x 15w) is oversized for your use, but it is probably the lowest cost.

A 12V LED light may be an option. Not sure if that would be cost effective, but they are about like a kerosene lamp. Me'n'you did fine with those, didn't we?

Boys!  Oh No!  I was thinking girls.  ;)    
(sorry Amanda & hotwire. I had to say it!)
G-

[ Parent ]



Re: Treehouse Wiring, 12v, solar panel (3.00 / 0) (#5)
by DanG on Tue Mar 28, 2006 at 02:13:39 PM MST

Valid 'promotions' from Harbour Freight, might help..

http://www.billt.com/harborfreight.htm

[ Parent ]



Re: Treehouse Wiring, 12v, solar panel (3.00 / 0) (#8)
by ghurd on Tue Mar 28, 2006 at 04:11:43 PM MST

Not sure what I did wrong.  Maybe this one is better.
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=90599

[ Parent ]


Re: Treehouse Wiring, 12v, solar panel (3.00 / 0) (#6)
by GDuncanson on Tue Mar 28, 2006 at 02:13:47 PM MST

http://21st-century-goods.com/page/21st/PROD/SPTCharge/BATTSAVSE6

This is what I bought, it hasn't arived yet. For the sake of the neighbors though, I wanted to keep my project sort of minimalist from the outside.

My boys wanted to use candles for light, that would be okay if they were older, but mine are 9,7,5; and I can trust them to climb safely but not play with fire in a wooden structure in tree.

Thanks again, I'm going to consider everything you've said, it's alot to digest.

~~geoff

[ Parent ]



Re: Treehouse Wiring, 12v, solar panel (3.00 / 0) (#9)
by ghurd on Tue Mar 28, 2006 at 04:18:52 PM MST

Geoff,
Just a thought.  
But the 2.5X more money gets something that is workable, with CFLs, controllers, etc.
G-


[ Parent ]


Re: Treehouse Wiring, 12v, solar panel (3.00 / 0) (#10)
by GDuncanson on Wed Mar 29, 2006 at 07:30:20 AM MST

Hi G,

I read through the threads you suggested last night. The solar garage project included a picture with a charge controller in the middle of the wiring. As far as I can forsee, I'll have a very similar wiring scheme without the charge controller. Does this mean I'll supply the lights and sockets directly from the battery? ie-each battery terminal will have two wires on it, one from the panel and one going to a terminal block?

[ Parent ]



Re: Treehouse Wiring, 12v, solar panel (3.00 / 0) (#11)
by ghurd on Wed Mar 29, 2006 at 07:46:37 AM MST

Yes.  
Or the panel wires can also go to the terminal block, so only one wire goes to each battery terminal.
Don't forget the fuses.
G-

[ Parent ]


Re: Treehouse Wiring, 12v, solar panel (3.00 / 0) (#2)
by coldspot on Tue Mar 28, 2006 at 09:31:09 AM MST

 GDuncanson-
Very cool to build for kids.
What ghurd has stated is good info
But, I'd fuse bolth sides of the battery
Pos & Neg, going in and out.
Also, depending upon the kids-
Building a locked or not battery box.
Before I was in junHigh I had built many things
that most adults didn't see or understand
Like a windsheild wiper motor auto bedroom door
opener, with a 10 key pad access code required to
operate the shocking the handle unlock, ( to keep little brothers out)!
So it's up to you as to lock or not!

Anyway, thats what got me here-
"TreeHouse" powered for self power.
Not for the kids but for a "Video Watch"
System for my girlfriends Cabin.
Security.
But mainly,
To film the BEAR that keeps leaving prints
By the back Door !!!
Being that I've never seen one in the wild,
Outside of Yellowstone Park that is,
And I live in the Wild state of IDAHO,
And spend a lot of time in the WAYOUT
places, so I'm very excited about this one!!!
I'm going to SHOOT it, With Film, NOT a GUN!!!
Digital all the way, Old style film sucks anyway!

Anyway, you might want to look into a
little wind mill for helping the "little",
Solar panel you got for the batterys.
:)



Re: Treehouse Wiring, 12v, solar panel (3.00 / 0) (#7)
by Opera House on Tue Mar 28, 2006 at 02:52:24 PM MST

This would be a great application for PTTC resetable solid state fuses.  I have some that are rated at 4A.  They have less than 0.1 ohm resistance,but can be placed dead short across and quickly limit current to about .2A current.  I'd be concerned about what two batteries in parallel can do.  I would at least put a 1 ohm resistor is series to any cigarette lighter plugs.  Better yet, put a headlight bulb in series to limit current. They have a very low resistance until they see a short.  These devices won't have any effect on most electronic devices.


Treehouse Wiring, 12v, solar panel | 11 comments (11 topical)
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