Noob requesting feedback: Will this LED design work?

Wallydrag

Newly Enlightened
Joined
Jan 2, 2016
Messages
6
My intention is to make portable field lighting for a roughly 45yd x 60yd soccer field. I'm going to have 4 of these for each corner but I'm really just wanting to know, first, if I'm on the right path with how I think I need to build these things. Right now I'm not concerned with if people think there will be enough light or not. Just about the power and circuitry of it all.

First, I already have these: DPD-4545-0809 15W COB LEDs.
Specs are:
15W
24V
562.5mA
1350Lm

The COB array is 8 parallels of 9 in series. My plan is to have 6 of these per light stand.


Portable means batteries. But I also don't want to be lugging a bunch of batteries of round so my thought was to use one (1) 12v rechargeable battery with an 18Ah capacity with a boost converter.

Here's the battery I'm wanting to use:
ExpertPower EXP12180 12 Volt 18 Ah Rechargeable Battery

This is the boost converter I think I want to use unless I'm told otherwise by more enlightened minds: Geeetech 150W Boost Converter DC-DC 10-32V to 12-35V Step Up Voltage Charger Module
The specs are:
Input voltage :10-32V
Output voltage: 12-35V (adjustable)
Output Current: 10A (MAX)
Input Current: 16A (MAX)
Output power: natural cooling 100W (MAX)
Module Properties: non-isolated step-up module (BOOST)

Now, my plan is to wire the LEDs up in parallel since there's no way I could get the voltage necessary from a battery for six of these LEDs in series. From all I've been able to find, I think I'll need to have a constant current driver for each LED (though my interpretation could easily be wrong). If such is the case, then I was considering using these: High Performance Constant Current Voltage LED Drive
The specs are:
● Output voltage: 2V - 30V
● Input voltage: 7V - 35V
● Output current: 3A (Max)
● Capacitance: 220uF
● Transformer efficiency: 92 percent(Max)
● Switch frequency: 150KHz
● Output ripple: 50mV (Max)
● 20M broadband
● Load regulation: +/- 0.5 percent
● Voltage regulation: +/- 2.5 percent
● Operating temperature: -40 - 85 degrees

So, is this all logical and realistic or am I going about this all wrong? Thank you all in advance for any feedback and expertise you can provide!
 

Str8stroke

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Nov 27, 2013
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On The Black Pearl
How long do you plan for this to operate in-between battery charges? IE: Runtime goals.

When you say 4 of these in each corner, can you be more specific? I am getting confused trying to figure it out. Help me. I am coming up with: 1 stand will run from 1 battery. That stand will contain 72 leds x 6 so 432! lol I think I am doing this wrong. Or, I am coming up with 54 leds per stand??????

It may just be me that is confused by this? FYI: Sounds like a fun project. Welcome to the forum.

I am having a hard time finding that specific led. Where are you getting it from? I know you already have it, but where from?
 
Last edited:

DIWdiver

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Jan 27, 2010
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2,725
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Connecticut, USA
Each COB has 72 dies, and you plan to use 4 COBs and a battery at each corner of the field, correct? If so you have enough energy to run the LEDs for around 3 hours while the batteries are new, less as the batteries age.

If you plan to run everything on one battery and one boost converter, you'll need twice that size battery to approach 1.5 hours of runtime, and you'll also need 500+ feet of two-conductor wire, probably 14 gauge to minimize voltage losses. Even with 14 ga wire, you'd loose something like 10% of your power just in the wires.

Whichever way you are thinking, your plan would work, but I think you can do better.

Running 4 COBs on one battery and one booster, I'd run all the COBs in parallel, and use a boost regulator with a constant-current output. With this setup you would not need separate boost and driver sections, as both functions are built into one unit. They look similar to the booster you linked, but they will say "CVCC", "CV/CC", "constant current" or something like that in the description. They will also have two adjustments on them.

Something like this should be nice: http://www.amazon.com/dp/B00X9WVNHU/?tag=cpf0b6-20

Or this: http://www.amazon.com/dp/B014J477TE/?tag=cpf0b6-20

Having both functions in one module and using short wires should improve the overall efficiency quite a bit and give you better runtimes for whatever batteries you end up with.

As far as the battery, ExpertPower is not a brand I recognize and respect. It has good reviews on Amazon, but the reviewers don't seem very technical and don't seem to have used it for very long. It's also pretty cheap and it's available primarily on eBay and Amazon, so I would expect to see it to work when you get it, but to perform below (possibly well below) the rated capacity and to have a shorter life than a better battery. It's possible that this battery is a real bargain, so I might be tempted to try it for an experiment, but if my league were depending on it to be able to play night games, I'd want some serious testing on it and some backups in place.
 

Wallydrag

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Joined
Jan 2, 2016
Messages
6
DIWdiver, thank you for that information. Each light will have it's own battery so I'm not worried about running wires all over the place (thank goodness).

It's great to know that I can essentially use an all-in-one unit with the boost converter/constant current unit like what you linked too. The simpler and less parts, the better.

I think I'm going to roll the dice on the battery. These won't be for night games but actually just providing light for practices until DST comes back and it quits getting dark at 5:30pm.

Again, I really appreciate your insight and suggestions!
 

SemiMan

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Joined
Jan 13, 2005
Messages
3,899
With that current draw, you are likely to get a lot less than 18AH.

I can appreciate if you are doing this "for fun", but this is not a great way to accomplish the underlying task, i.e. lighting a soccer field. In your described setup, yes the lighting level will be low (which you perhaps already know) .... even with 4 per corner, and unless you can get them up 30 feet or so, glare and coverage are going to be an issue. I think you will find life much easier (with a better chance of getting it into the "field" so to speak), if you invest in a couple of 3000W or so generators and extension cords, and run dual sets of 400W MH lights in each corner. The need to get the lights up high for a somewhat portable installation and having them be safe is likely to be the big design challenge.

If you wish to continue on with the LEDs, personally I would toss the COBs that you have already bought and save them for something else. If you must run off batteries, then efficiency is everything and there are much more efficient COBs, i.e. 50% more efficient at rated current, and higher if you run them at lower current. You can also get bigger ones, which means fewer reflectors, less MFG, etc. The added cost of the COBs will be recovered in reduced battery cost (especially over time), electronics, wiring, etc.
 
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