Lipo batteries and LEDs

DISCLAIMER: I am not a electrician. I know absolutely nothing aside from a few basic terms and concepts. Please keep any answers to this post reduced to the simplest words and terms so that I can keep up. lol. Im not an idiot, this just isnt my normal area of operations.

I have been toying around with making my own dive lights for some time now. My recent goal has been to make a wide beamed flood light that will make my gopro footage full color and not have any hot spots. I bought 4 XML emitters, small drivers, and some of the rechargeable 18650 batteries. well, that project got put on hold for a while and has recently popped back into my to-do list. i was looking at my components and started wondering if I could use some of my Lipo batteries that are fuctional, but older and not quite working up to par with my newer ones. After some research I see that it is possible but I need a new style of driver.

my plan is to gut an old dinosaur UK light and convert it to my flood light. For now Im thinking that if I can get all 4 emitters close to the lens with a slight outward angle I can get a pretty bright and clear light to make my camera see in full color without a hot spot. i want to run one or two of my 3000 mah lipos in the light case (its a big housing) and drive all 4 of the lights at one time.

what driver would I need to run all 4 emitters? can I use some simple math and say that if each emitter needs 3v that with 4 emitters that a 12v output will be okay?

again, i am not an electronics whiz and I dont get into the all the tech mumbo jumbo. any help you could provide would be greatly appreciated.

Thanks for the help guys.

again, i am not an electronics whiz and I dont get into the all the tech mumbo jumbo. any help you could provide would be greatly appreciated.

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Not yet you're not! So you're going to run the emitters with no optics. Ok.

Start with the basics. Exactly what lipos do you have? What voltages? If they are used, it might not be a good idea to marry more than one of them in a circuit.

Lipos do well with high draw, you could likely drive the 4 emitters from one lipo pack.

As far as the driver, there's choice. Are you intending to run the emitters parallel or series?

1 driver for all 4 or 1 driver for each? 4 xml emitters, same bin/type?

Have you ditched the idea of using 18650?

How are you going to mount and heat sink the 4 emitters?

Just to give some background , I am an RC pilot and I build my own electric planes. I solder my own components and am familiar with the ins and outs of lipo charging/maintenance/safety. So I'm not a total noob, I'm just a surface dweller just starting to peek under the outer layers.

I'm using an old incandescent UK dive light housing. It's huge. It used some kind of old 6v 2 pole wonky heavy batteries. I didn't realize it was so big when I bought it from the bay. I was gonna scrap it but then decided to see what I could do with it anyway. I had already decided the el cheapo 18650's were a no-go and decided to see what I had on hand rather than spend more $$. I have some 3000 mah 3 cell lipos that peak at 14v, run continuous at 12v, and of course drop off to the danger zone as they are not circuit protected.

The light body is perfect to hold two of these 3000mah bricks. The reason I picked these two batteries is that they just don't have the oomph to push a prop anymore. They will run a video transmitter just fine or even my sons RC truck. They just won't spin the prop like they used to. So for the dive light I think they will work fine. If nothin else they prove a concept and I can just buy new ones.

I am actually toying with the idea of keeping the reflector in the light head. It has a hole in the middle where the bulb goes but I can remedy that. I could either:

Find something to mount the 4 emitters on that fits between the glass and the reflector that allows me to mount the emitters close together flat or tipped up in the center so that they more or less create a "dome" of light. This would give me a nice heat sink as well as keep the emitters close the the glass.

Or, drill 4 holes in the reflector and mount the emitters evenly behind the reflector and allowing the bulb portion to protrude through. This would give me 4 angled emitters that would hopefully give a wide beam and still use the reflector to spread light. My only worry would be a hot spot in the middle. An adhesive diffuser on the lens might fix that but I'm not sure at this point.

The housing has a watertight rotator switch that is designed to press metal contacts together. I can use a magnet and reed switch to with the stock switch to make a super easy power switch.

I have 4 identical Cree XML emitters. I've had them for quite some time now. I don't think I bought the T6. I want to say I bought the upgrade of the T6 that's more efficient. It's been almost two years so I can't recall the specs or even where I bought them. I do recall they have the potential for 1000 lumens each. I figured 600-800 optimistically and 400-600 realistically. With 4 I reckoned I would be be able to get close to 2000 lumens +/-

My goal is to be able see color with my GoPro on dives. The deeper you go the more color you lose because the water filters out everything but blue. However, if you introduce a fresh light source you get colors back. The GoPro isn't equipped to shoot far under water so I don't need penetration power in my light. I need strong diffused flooded light in the immediate are of the lens so that when I'm within 5' of a target I start to get some colors in the video.

So, with that being said. I want to try to use lipos to power a semi strong to hopefully a full power (fingers crossed 4000 lumens?!?!?) LED flood light. As to running the emitters/drivers in series or parallel, to me that is dictated by what the emitters need vs what they can or can't handle and what works best without burning components up. The heat sink is something I'm still working on. I think I have room in the lens assembly to create one. The only issue is that it will be enclosed in the light body with no direct contact with water. As to how many drivers, again that is dependent on what I need at this point. I only have the little nickel sized drivers right now and I'm pretty sure my lipos would melt them. I think their input voltage is only 3-5v maybe? They would be fine for 18650's but not the 3cell lipo. I'm okay with buying new drivers, I'm just lost to what ones to pick and then how many.

While I would love a 4000 lumens flood light I also realize that is pushing the emitters to the max which equates to a lot of heat. This case isn't conducive to shedding heat efficiently so I know I have some design limitations that play into this.

Is that enough info?

Hmm.

Well, for starters, you're going to have to ditch the reflector or black it out. I learned that trying to mod a led 1 emiter spotlight by swapping in a 3up star. The beam was HORRIBLE. Gotta ditch reflector or black it out with flat black spray paint or similar.

Sounds like you've got a lot of room to work with, that's good.

Next up, your thermal path. 4 emitters at max drive is going to pump some heat. To keep from frying, you're going to have to come up with a heat sink and bond it somehow to the housing. At that point, heat shouldn't be an issue underwater. There's some dive lights that aren't supposed to run on dry land due to the extra cooling of the liquid bath. Also: What's the case made of? Aluminum? Once you fix the thermal path, the water should do the rest for you.

3-5v in drivers won't cut it, you're absolutely correct. Perhaps check out TaskLED? They've got what you're looking for, particularly since you've got a lot of room to work with. If you can't find exactly what you're looking for, you could indeed go with a driver for each. This would also give you extremely fine control of output as the 4 emitters could be driven differently for juuuuuust that right touch of light.

Alternatively, you could wire the leds in parallel and pick the TaskLED driver that fills that bill. You'll not have as fine control of the output.

Next up: How is your light switched? This will be an issue if you're using 4 drivers and want to drive the emitters differently.

Thanks for the info on the reflector. Sounds like I'm blacking my reflector out.

Depending on the size drivers I need I think I can grab some stainless hardware and make a heat sink that passes through the lightbulb hole back into the flashlight body. I can mount the emitters to the metal hardware using thermal paste or a thermal pad to ensure good heat transfer. I have a few options here that I think will again be dictated by the type driver I end up with.

The body is heavy plastic. Without heavy modification I won't be able to directly dissipate heat into the water. I have a smaller light that uses a standard high power light bulb. It is the kind that cannot be used out of water because the bulb will melt the lens. There is no heat sink aside from the flow of cool water over the case. Granted it's not a lipo powered LED running at full force.

My power switch is built into the light. It simply swivels. On the inside is an egg shaped plate that when rotated presses contacts together. I will be removing the OEM contacts because I cannot incorporate them. I can either rebuild a similar switch or slap a magnet on the disc and have a magnetic switch. I may opt for the simple mechanical switch.

I haven't decided on how I want to run the emitters. Do I want a high/low option? I don't know to be honest. I know that I DO NOT want the typical cheapy driver option of high/med/low/flash/SOS. I hate that.

I will look at the sites you described, though I may be right back here still wondering what I was looking at.

Hmmm, might have to keep your total draw under 2-3 amps because of the plastic housing. You might not be able to push as hard as if it were metal. Plastic kind of insulates.

I can live with that so long as they still light me up.

Well rock on then, sir!

Come back with more questions.

Wow those drivers are pricey. One of the points of this build is to save $$.

So tell me, do I want to run them series or parallel? What's the advantage of either way?

I keep seeing mah used to describe the draw. From charging my lipos I think I understand that 1500 mah corresponds to 1.5 amps. Is that correct? I think the max for my emitters is 3 amps. Help me with some LED theory and terms here.

???? http://www.ebay.com/ulk/itm/300964147007

debay777 said:

Wow those drivers are pricey. One of the points of this build is to save $$.

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There is an art to budget modding. Many say to heck with it and go for the gusto. Often times in my experience, a serious flashlight hobby is only slightly less expensive than firearms as a hobby.

debay777 said:

So tell me, do I want to run them series or parallel? What's the advantage of either way?
In series, you drop voltage across each emitter. In series, you must push more voltage to drive the LEDs correctly. LEDs are not run by voltage, they care about current; we call it "current controlled." The actual voltage fluctuates with temperature and such.

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In parallel, the emitters see the same voltage but the current is divided among the 4 paths for four emitters. The driver must push differently, the current is divided by 4.

https://en.wikipedia.org/wiki/Series_and_parallel_circuits

Components of an electrical circuit or electronic circuit can be connected in many different ways. The two simplest of these are called series and parallel and occur frequently. Components connected in series are connected along a single path, so the same current flows through all of the components.[1]​[2]​ Components connected in parallel are connected so the same voltage is applied to each component.[3]​

A circuit composed solely of components connected in series is known as a series circuit; likewise, one connected completely in parallel is known as a parallel circuit.
In a series circuit, the current through each of the components is the same, and the voltage across the circuit is the sum of the voltages across each component.[1]​ In a parallel circuit, the voltage across each of the components is the same, and the total current is the sum of the currents through each component.[1]​

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debay777 said:

I keep seeing mah used to describe the draw.

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Though milliamp-hours are a factor in a circuit, the draw itself is measured in amperes or amps. Abbreviated with A. Milliamps, mA.
https://en.wikipedia.org/wiki/Ampere

The ampere (SI unit symbol: A), often shortened to "amp",[1]​ is the SI unit of electric current[2]​[3]​ (dimension symbol: I)[4]​ and is one of the seven[5]​ SI base units. It is named after André-Marie Ampère (1775–1836), French mathematician and physicist, considered the father of electrodynamics.

The ampere is equivalent to one coulomb (roughly 6.241×1018​ times the elementary charge) per second.[6]​ Amperes are used to express flow rate of electric charge. For any point experiencing a current, if the number of charged particles passing or the charge on the particles is increased, the amperes of current at that point will proportionately increase.

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Mah is one measurement of the capacity of a battery. Milliamp-hours. This number by itself doesn't actually mean much, you need to calculate "watt-hours." Watt-hours are more like the actual power the battery can generate and this number changes depending on the draw. For example, alkalines can have decent watt-hours at very low draw. Try to pull 1.5 amps out of alkalines and the watt-hours decrease!

https://en.wikipedia.org/wiki/Ampere-hour
https://en.wikipedia.org/wiki/Kilowatt_hour

debay777 said:

From charging my lipos I think I understand that 1500 mah corresponds to 1.5 amps. Is that correct? I think the max for my emitters is 3 amps. Help me with some LED theory and terms here.

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Close, very close. As a rough rule of thumb, 1500 mah at 1.5 amp draw is a discharge rate of "1 C."
https://en.wikipedia.org/wiki/Battery_(electricity)#C_rate

The C-rate is a measure of the rate at which a battery is being discharged. It is defined as the discharge current divided by the theoretical current draw under which the battery would deliver its nominal rated capacity in one hour.[30]​ A 1C discharge rate would deliver the battery's rated capacity in 1 hour. A 2C discharge rate means it will discharge twice as fast (30 minutes). A 1C discharge rate on a 1.6 Ah battery means a discharge current of 1.6 A. A 2C rate would mean a discharge current of 3.2 A. Standards for rechargeable batteries generally rate the capacity over a 4 hour, 8 hour or longer discharge time. Because of internal resistance loss and the chemical processes inside the cells, a battery rarely delivers nameplate rated capacity in only one hour. Types intended for special purposes, such as in a computer uninterruptible power supply, may be rated by manufacturers for discharge periods much less than one hour.

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debay777 said:

???? http://www.ebay.com/ulk/itm/300964147007

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Hey, that thing looks cool! No idea how you're going to hack it in a dive light and maintain waterproofing.

Well now, looks like this has turned into a "1000 level" "Intro to Flashaholism for Engineers."

If I were to use that driver it would be kept safe inside the light body. It would give me the capacity to start low and push the emitters from min capacity to full capacity, or as close as I can get with the lipos I have. I have way more than just the two 3000 mah bricks choose from. I have a truck load of 2200's and 1500's. Most are rated for 20-30 C. A few are 40-60 C.

Would you say this driver has a shot at doing what I want?

And I totally understand the flashlight addiction. It kills me to see some of the adds online and then see that the 4 million lumen micro pen light is $400. That's an exaggeration of course but you get my drift.

This project was inspired by a fella from South Africa who used common plumbing fixtures to build his own GoPro lights. They came out awesome. I couldn't get the same fixtures so I had to improvise. That ultimately failed because Of component selection, design flaws, and some lack of understanding. Hence my decision to go with a manufactured light body. That takes 90% of the difficulty out of the equation. If I had a CNC machine and aluminum stock laying about I would have my lexan tube light made. But alas, I do not and thus....I do not. LOL. So now I'm down to component selection and assembly. And I'm taking my time so as to avoid further issues. Just so you know I've seen DIY voltage regulators that cost less than $5 to build. They don't have any bells or whistles and you have to understand resistors and they play into amps/watts/voltage and all, but still, < $5 is good.

Oh, I found an online calculator that gives you 3 variables. Plug in any two and it gives you the missing third. I see now how volts/amps/watts work together. If this e at CCdriver plays out I think I can do this.

debay777 said:

If I were to use that driver it would be kept safe inside the light body. It would give me the capacity to start low and push the emitters from min capacity to full capacity, or as close as I can get with the lipos I have. I have way more than just the two 3000 mah bricks choose from. I have a truck load of 2200's and 1500's. Most are rated for 20-30 C. A few are 40-60 C.

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I guess you could set it, turn it on, close the light body with it in there and take it apart to adjust. That'd be kind of annoying, but would work. That driver looks pretty useful, btw. Definitely a flashaholic lab toy.

debay777 said:

Would you say this driver has a shot at doing what I want?

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Sure looks that way.

debay777 said:

And I totally understand the flashlight addiction. It kills me to see some of the adds online and then see that the 4 million lumen micro pen light is $400. That's an exaggeration of course but you get my drift.

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Best advice I can give you is BE CAREFUL. Ads are the devil. Check this out:
http://www.candlepowerforums.com/vb...he-Most-Overpriced-Budget-Lights-in-the-World
In that thread, we're posting the biggest rip-offs we've found. We talk about false advertising. It's a real threat to your wallet and perhaps your safety. There's a million a-hole scammers out there wanting to charge you $150 for a $10 light.

debay777 said:

This project was inspired by a fella from South Africa who used common plumbing fixtures to build his own GoPro lights. They came out awesome. I couldn't get the same fixtures so I had to improvise. That ultimately failed because Of component selection, design flaws, and some lack of understanding. Hence my decision to go with a manufactured light body. That takes 90% of the difficulty out of the equation. If I had a CNC machine and aluminum stock laying about I would have my lexan tube light made. But alas, I do not and thus....I do not. LOL. So now I'm down to component selection and assembly. And I'm taking my time so as to avoid further issues. Just so you know I've seen DIY voltage regulators that cost less than $5 to build. They don't have any bells or whistles and you have to understand resistors and they play into amps/watts/voltage and all, but still, < $5 is good.

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Another option is the humble limit resistor.
https://en.wikipedia.org/wiki/Resistor#Power_dissipation

At any instant, the power P (watts) consumed by a resistor of resistance R (ohms) is calculated as:

where V (volts) is the voltage across the resistor and I (amps) is the current flowing through it. Using Ohm's law, the two other forms can be derived. This power is converted into heat which must be dissipated by the resistor's package before its temperature rises excessively.

Resistors are rated according to their maximum power dissipation. Discrete resistors in solid-state electronic systems are typically rated as 1/10, 1/8, or 1/4 watt. They usually absorb much less than a watt of electrical power and require little attention to their power rating.

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Basically, you can use a dumb non-reactive resistor to limit the current flow. The down side to this is you now have diminishing output as the batteries drain. This bypasses the need to have some specific driver and is the simplest way to proceed.

Don't select a limit resistor with too low of a wattage rating or else you'll smoke it.

Yeah I know better. Too many are the in TGTBT range. 1000 lumens on 3 AAA's for an hour? Reeeeaaaaalllyyyy.

debay777 said:

Oh, I found an online calculator that gives you 3 variables. Plug in any two and it gives you the missing third. I see now how volts/amps/watts work together. If this e at CCdriver plays out I think I can do this.

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You could use that variable driver set to constant current, or simply use a limit resistor with a high enough wattage rating and go that route.

debay777 said:

Yeah I know better. Too many are the in TGTBT range. 1000 lumens on 3 AAA's for an hour? Reeeeaaaaalllyyyy.

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Almost all AAAx3 lights are junk and lies.

Anyway, if you wanted an actual tiny blaster:
http://www.candlepowerforums.com/vb...VN-Brightest-amp-Most-Advanced-Keychain-Light
http://www.candlepowerforums.com/vb/showthread.php?407539-TOOLvn-Best-IMR10440-Clicky-of-2015

So help me out in terms I can grasp.


4 LEDs in parallel. With say a 3v constant source I'm sending 3v to each emitter. That's a 12v total drain on the lipo which is the approx peak capacity of the battery. That will eventually slope off down to my min which is about 9.9v. Any lower and I risk damaging my lipo. So explain to me what I'm doing to amperage and /wattage.

And the same with series. Stringing the emitters in parallel is spreading the voltage across all 4 emitters, effectively dividing the available 12v power source by 4 and giving me about 3v per emitter. I understand that this affects the amperage and wattage differently than running parallel. How so.

Just watched a video. Think I understand. In parallel I will be able to draw more amps per emitter and have a brighter leds. In series they will draw less amps and burn dimmer.

Series will potentially burn battery slower but with reduced performance. Parallel will increase performance but reduce battery life.

With that eBay CCdriver I can dial up the amps for series connections and still have strong lights and still eat my batteries. In parallel I'm not sure that CCdriver will help me. Unless I would just up the voltage output which should also by default increase amps. Is that correct?