Lighting Plan - requesting comments

[Ninja Nemo]

I'm building a deep playa art installation, hoping to power a single 10W DC flood light w/ a single battery.

(light -

I asked around on eplaya in the past and got some good advice on the math. From what I understand, the light (DC) consumes 10 watts / 12VDC which means it will consume 0.83aH. My installation will be lit about 8 hours per night, which means a consumption of 8.33aH/night or 83.33aH for the 10 days it will be set up.

Based on this, I understand that I could probably buy a single 100aH deep cycle battery and be set for the week? (I know I shouldn't drain past 50% if I want to reuse, so I may try a mid-week recharge @ SolarKoan for long-term longevity).

I also need to find a DC timer for the light but I'm guessing the consumption won't be enough to matter?
(planning on grabbing this -

Besides that, I just need a battery box and wires to connect everything. Is this correct? Is there anything else I need to consider?

Thanks!

[strange love]

Consider getting a solar powered trickle charger for the battery.

[Captain Goddammit]

It looks like you've got a workable setup figured out. You might consider two batteries hooked up parallel, just so you can run it all week and most likely not have to deal with recharging them.

[mudpuppy000]

If you read the comments on that light, it's actually wired for A/C 110V. You can take it apart and bypass the transformer in it if you'r comfortable doing things like that.

A trickle charger seems like it'd be great to have as well.

[maladroit]

A 15W to 20W solar system will set you back something like $50-$100 not including battery. You have to calculate whether spending a day lugging your battery over to solar charge, babysitting it, then dragging it back is worth saving $100.

[Captain Goddammit]

If you read the comments on that light, it's actually wired for A/C 110V. You can take it apart and bypass the transformer in it if you'r comfortable doing things like that.

A trickle charger seems like it'd be great to have as well.

I didn't read all about it but I was a little curious, a light like that one seems unusual to find for sale set up for 12VDC.

Like mudpuppy said, if you're comfortable with such things you can rewire it, or simply use a small cheap inverter if you aren't, but my experience so far with cheap non- pure sine wave inverters and LEDs is that they flicker and don't achieve full brightness because of the "modified" sine wave AC the cheap inverters produce.

[CornMan]

Would a propane lantern hooked up to a 5 gallon tank work? I've spray painted the glass globes with high temp engine paint, and that works well. You could paint part of the globe with silver high time paint to make a reflector so it doesn't blind the people looking at the art.

[Ninja Nemo]

Thanks for the replies, so I'm taking it that my math is solid?

The reviews of the light seemed like that it is designed as 12VDC with the transformer to 120A/C installed for their AC version. I've ordered ahead of time to hopefully allow for returns & reshipment if they send me the wrong model.

I think I'll definitely grab that solar panel, there's a 2 pack for $75 which seems better than 1 for $50 and will let me trickle charge my camp battery too! It would be nice to have a little something extra to give me confidence that the battery will last and mitigate needing to haul the battery around the playa mid-week.

The propane lantern is a good idea, although my project isn't currently approved to have any type of fire, and I don't know if I feel like jumping through the necessary hurdles at this point.

Thanks again and come find the Garden of the Playans somewhere deep playa!

[percussivepaul]

Re: the math I find it way easier to convert battery capacity to Watt-hours, rather than working in Amp-hours. A 100Ah-12V battery has max 1200 Watt-hours, of which you can count on about half, so 600 Watt-hours. Which is 60 hours of your 10W bulb. Almost enough for the 80 hours you wanted; add a trickle charger and you're good for sure.

[Ninja Nemo]

Re: the math I find it way easier to convert battery capacity to Watt-hours, rather than working in Amp-hours. A 100Ah-12V battery has max 1200 Watt-hours, of which you can count on about half, so 600 Watt-hours. Which is 60 hours of your 10W bulb. Almost enough for the 80 hours you wanted; add a trickle charger and you're good for sure.

Huh, that's a much simpler way of doing it. Out of curiousity, why do you say I can only rely on 50%? I understand that draining past 50% isn't good for longevity, but why wouldn't you get the full 1200 Watt-hours out of the battery?

[mudpuppy000]

Re: the math I find it way easier to convert battery capacity to Watt-hours, rather than working in Amp-hours. A 100Ah-12V battery has max 1200 Watt-hours, of which you can count on about half, so 600 Watt-hours. Which is 60 hours of your 10W bulb. Almost enough for the 80 hours you wanted; add a trickle charger and you're good for sure.

Huh, that's a much simpler way of doing it. Out of curiousity, why do you say I can only rely on 50%? I understand that draining past 50% isn't good for longevity, but why wouldn't you get the full 1200 Watt-hours out of the battery?

You should get the full charge out of it, but at the expense of damaging the battery. It might not charge to capacity when you go to recharge it.