One of my hotels in Phuket has a new lightbox 'directions' sign (100x100cm), mounted on a pole by the main airport road.

This sign is two-sided, and there are two 220v fluorescent tubes inside the box for illuminating the sign at night.

Now here is the problem:

The sign is too far from our hotel to enable me to run a 220v cable. Our intention was to make a deal with a pizza restaurant next to the sign to use their electricity, but that restaurant has now turned into a guesthouse, so it is no surprise that they will not now co-operate in providing us with the 220v supply....

There are no other premises nearby from where we could obtain a 220v supply.

So I need to find a way to illuminate this sign at night. Solar lighting is too weak (I've tried that before).

I was thinking of using two 12v fluorescent tubes that are powered by a car battery in a locked box on the mounting pole - I could swap out the battery every day if needsw be.

But then I see on Google that one can buy the LED equivalent of a 12v fluorescent tube, providing the same or higher candela output for a much lower current consumption.

Does anyone have the technical data for these types of LED lights? I want to calculate if it is feasible to power two of these LED strips for about 8 hours each night, (powered on/off via a dark-sensing switch). What sort of battery could power these lights to enable 8 hours of use, with battery re-charging/swap-out each day?

Simon

Depends on the wattage of the lights, but here some math for when you figure that part out..

Note: assuming 12vdc lamps.

( a ) Total Watts ÷ 12 = How many Amp Hours (Ah) of current draw the lights will consume.

( b ) a × 8 = Current req'd for 8 hours operation.

( c ) b × 2 = How many 12V battery amp-hours you will need (at 50% depth of discharge)

Once you have the batteries, it's not hard to go the next step and make them recharge by solar.. But if might be physically not feasible on a sign board.. Either way, you're going to need a charger that generates at least ( a ) amps to recharge it again for use again every day.

If you want to only recharge it every 2 days, multiply ( c ) by 2, and the charger will need to be ( a ) times 2 (or bigger) to get it recharged in a day.

Edit: fixed the auto-smileys

Final note: beware of the lumens claims of Chinese LED lamps.. Some are exaggerated beyond belief.

Edited June 7, 201412 yr by IMHO

As this is a double sided sign and LEDs tend to be single direction I would just get a number of the 12" (8 Watt) 'car' fluorescent fittings, 4 would probably be enough to make it visible at night. Maybe strip out the works so the tube is better exposed inside the sign.

They pull about an Amp, so for 8 hours you'll be needing 8 * 1 * 4 = 24Ah @ 12V 1 or 2 50Ah car batteries should do the trick (you really should use deep-cycle marine batteries, $$$ ).

Amorn Solar do panels and charge regulators, 12V timers on Ebay.

Not going to be a cheap option, is it absolutely impossible to get mains to the sign?

EDIT A couple of these would be handy http://www.ebay.co.uk/itm/12V-DC-Dark-Activated-Photo-Control-Switch-Circuit-Lamp-/261383559877?pt=UK_DIY_Material_Electrical_Fittings_MJ&hash=item3cdbac9ac5

Have you tried contacting PEA to see if it's possible to install a separate meter nearby?

Probably cost prohibitive, but you could ask.

Also, they've been installing these solar lamps in and around our village. The placement of this particular one is likely to be the CAUSE OF A POWER OUTAGE requiring it to be the alternative light source.

It puts out a decent amount of light, enough that I'm glad they didn't install one across the road from our house. A similar setup would work fine for a SignBox, well, minus the direct contact with an overhead live wire.