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KoolMoe
Aw Man
Premium Member
join:2001-02-14
Annapolis, MD

KoolMoe

Premium Member

rig motion detect w. solar

Currently have outside lights with two motion detectors. Lights themselves are hardwired but the detectors take two AAA batteries each - and they run through batteries pretty quick (change 3 times a year and a pain to do).
I have a small solar panel made for charging AA/AAA batteries. I'd like to rig that outside and run wires from the panel to each detector.
-what gauge wire would be best?
-I need to waterproof the panel. Make a small pexiglass box?
-How to best afix it to the shed roof?
-better to put the batteries in the charger and run wires to the detectors? Or run wires from the charger to the batteries in the detectors?
And any other thoughts/insights appreciated!
KM

leibold
MVM
join:2002-07-09
Sunnyvale, CA
Netgear CG3000DCR
ZyXEL P-663HN-51

leibold

MVM

Unless your cable is going to be very long and you have issues with resistance and voltage drop any gauge will be fine for the small current.
However since you plan to use it outdoors I would make sure that the chosen cable is UV resistant and suitable for direct burial. The easiest source is your nearest home and garden store where you can find multi-conductor sprinkler cable.
I don't know to which extend UV light contributes to the photovoltaic process inside a solarcell but you should expect at least some reduction in output because plexiglass (depending on type) blocks some or all of the UV light.

nunya
LXI 483
MVM
join:2000-12-23
O Fallon, MO

nunya to KoolMoe

MVM

to KoolMoe
For all the trouble, wouldn't it just be easier to get MD lights that do not require batteries. TBQFH, I've been in the electrical business a long time and never happened upon a MD fixture that needs batteries.

KoolMoe
Aw Man
Premium Member
join:2001-02-14
Annapolis, MD

KoolMoe

Premium Member

Detectors are mounted under roof of outside shed, and best spot for this small solar panel is on the roof of the shed (or mounted to the side, but then less sun exposure)...so no burying of wires. At best, would run under shingles to sides of shed then run under the overhangs.

Yes, easier certainly to buy a new setup, but I already have this setup and it works just great, aside from battery usage. The MD's with batteries are one reason I chose this package (maybe silly now .

I already have this battery recharger panel, been kicking around for years, so figure I may as well use it...

I've got a lot of wire left over from some battery/DC runs in my car, so guess will just try that. Biggest hassle will be an enclosure, but a little wood and plexiglass - not hard at all. Just something I want to try...have pretty much all parts I need, so why not... If it saves me the hassle of swapping batteries to just once a year, cool enough

If/when I get around to it, will take picts.
Any other ideas welcome!
KM

cowboyro
Premium Member
join:2000-10-11
CT

cowboyro to KoolMoe

Premium Member

to KoolMoe
If it was made for regular batteries it may not like rechargeable batteries. They provide ~1.2V vs the typical 1.5V for "regular" batteries.
Try with fully charged NiMH and see if it works for few days. If it does then you might have a chance of using one panel per device.
If you want to share the charging circuit you must be positively sure that there is no galvanic connection between the batteries and the AC side - in other words that the switching is done via a relay rated at least 500V between contacts and coil (or an optocoupler). Otherwise the insulation may break down if the lights are on different legs of the AC.

If you can confirm that, the wire gauge is insignificant. The current delivered by a smallish panel is very small to start with, and you will further limit it with resistors so that you don't overcharge the batteries. Hell you can even use telephone wire...
In all honesty it's not worth it, just get a normal detector...