What if I can make room for 3 18650 batteries, will they be able to power 10 LEDs? They're almost 12V, so maybe they're better than an 8*AA pack as they take up less space?
Will I then need a protection board? I've never had to use those, what does the protection board do and how do I wire it?

 

This is from one of your links and shows the connections for the LEDs.
If you use 18650 or other LiPo cells. you will need a battery charger/protector board otherwise you run a good chance of overcharging and exploding the batteries or killing them by over discharging them.
The internal resistors on the strips are for current limiting. Those strips are designed to run on a fixed voltage, usually 12V. Some LED drivers are constant current controllers and have active current limiting inside them so there is no need for external resistors. But you will need to find what the current setting is and use appropriate LEDs.
Also, the controllers in your links will have all the LEDs of the same colour running at the same intensity I think.
I still vote for the addressable LEDs

 

I do want all to run at the same intensity. It would be cool to program different areas to different color patterns, but I really just want the light feature to be as simply as possible. I promise I'll upgrade it one day to arduino, but at first it'll just be running on a driver.
I don't think the drivers control the current, I think they just output the input current. That means I'll have to match the battery voltage to the LED consumption, right?
Say I have 3 18650 batteries and a protector board. That means I'll have 11,1V (assuming the protector board doesn't limit anything?).
I suppose the voltage will then be 11,1V on all three channels and the current is split? Correct me if I'm wrong, I can never remember when voltage or current is distributed...
But say I'm right, then. The red is 2,3-2,6V and the green and blue is 3,4-3,8V. Does that mean I can have three LEDs in a section? Then I would need to split my output from the driver into three sections to run 9 LEDs?
Then, how do I run the last LED?
Do I need to have a resistor on the red channels to compensate for the slightly lower voltage?

 

I think those drivers are just FETs (switches) to 0V so there is no current control. Each LED in the strips have their own resistors.
So, to work out the resistors needed, Resistance = Volts on Current, R=E/I.
So, if you have one LED and 12V, and want the current to be 20mA, you work it out as follows....

R = (SupplyVolts - LEDVolts)/Current
(assuming 12V supply, the LED has a voltage drop of 2.5V, and you want 20mA current)
R = (12-2.5)/.02
R = 11.5/.02
R = 575 ohms

If you have 2 LEDS,
R = (12-(2.5x2))/.02
R = (12-5)/.02
R=7/.02
R=350 ohms

So, you can calculate the resistor value needed to limit the current for any number of series LEDs. But you need to find out the forward voltage drop of the LEDs as that varies with colour and type.

Does that help, or confuse you?

 

I think it both hepls and confuses me ;-)
Say my LEDs work in the range 350-1000mA. I suppose I would want 750mA or something, but I'm actually not sure if the current will determine the max brightness. Do you know?
Anyway, how do I know what the current is when I'm using batteries?
Do I put the resistors in front of the LEDs or after them? Does it matter?

 

Am I correct in my assumptions in #23? can I run sections of 3 LEDs in parallel from the driver?
And how do I then run the last LED if I want that one? And calculate the current?
I suppose this is the time when I decide to actually try to understand it so I can work out this stuff for myself later... ;-P

 

I think it both hepls and confuses me ;-)
Say my LEDs work in the range 350-1000mA. I suppose I would want 750mA or something, but I'm actually not sure if the current will determine the max brightness. Do you know?
Anyway, how do I know what the current is when I'm using batteries?
Do I put the resistors in front of the LEDs or after them? Does it matter?

It is best to not run the LEDs at their max current for better life.
350mA is a bright LED. Do you want spot lights or just decoration?
And at those currents, the batteries will not last real long.
LED brightness is determined bu the current. They are current devices.
The placement of the resistors does not matter. But if you are going to have those sorts of currents, a switch mode current controlled supply is what you want. But, operating that in a guitar could cause a lot of noise pickup.
Prototype it first before hacking into your guitar just to make sure.
And if you do use current limiting resistors at higher currents, you will need to take into account the power dissipation of the resistors.

 

So is 350mA problematically high current?
I just looked at the batteries. They're rated up to 15A... So how am I supposed to know what current I have? Do I control it somehow?
Also, do I need a 11,1V protector board for three batteries? I really don't know how they work.

 

The LED current is controlled by the series resistors.
A 20mA high intensity LED is very bright. A 350mA LED is used for lighting applications.
When you run LiPo cells in series to increase the voltage, a charge controller is needed to balance the charge between the cells. You may have seen a board inside a laptop battery if you have pulled one if them apart. LiPo cells are pretty good power supplies but are fussy charging and over discharging. Charging them incorrectly can result in fires. And under charging can kill them.
I'm partly incorrect when I say "LiPo" but it is easier to type
Have a look at...
https://batteryuniversity.com/learn/article/charging_lithium_ion_batteries

A 15Amp supply will not force 15Amps through the load. The amount of current is determined by the voltage and resistance of the circuit.
I = E/R (current = voltage over resistance)
Think of a 12V car battery. It is capable of some hundreds on amps to start the car, but if you have an LED indicator in the car, it will draw a few milliamps only.

You may find it all easier to use Alkaline AA cells for you LEDS, but do look at lower current ones. There is no need for such high current LEDs unless you are looking to replace the stage spotlights

 

I actually want it to be able to glow really bright if needed. I will probably have them turned way down at most times, but I'm hooked at the possibility to have the thing flash really bright for music video and stage effects purposes
I know these LEDs are really bright. I've used similar ones for a reef aquarium lamp once, and I like them a lot.

So... Say I have the voltage determined: 11,1V. Would I be correct in saying that the current is spil over the parallel sections of three LEDs and the voltage isn't? Then I would require 3,15A to run my system of 3*3 colors at 350mA each.
Now here's a point where I really doubt myself: How much resistance do I have in the circuit?
I=E/R - My LEDs are each taking 3,7V*3=11,1V at 350 mA, giving me a resistance of 0,03171 ohms? How do I know if I have that resistance?
Also, can I calculate it this way when I'm adding a resistor to the red channels? Following the same formula I calculate that they will have a 0,02141 ohm resistor.

 

I feel like I'm using the wrong numbers in the wrong places...

 

You will have real trouble running these high powered LEDs on AA batteries. I think you need to look again at what you want to do.
Just consider, a 6Watt LED lamp has similar light output to a 40watt incandescent one. You are talking of having the equivalent to about 200Watts of incandescent lamps running.
You may need to look at something like this...
https://www.ebay.com/itm/HRB-18-5V-...570321?hash=item1a51fb40d1:g:UrEAAOSwrCZbGOWb
And a charger/balancer to suit.That uses the multipin connector you can see on the battery pack.
A 11.1V 2200mAH version is smaller, and that may work for you if less than an hour's full brightness operation is ok.
One thing to determine is how long you need to run these LEDs, then the total power, so you can work out how big the battery needs to be.

 

That's sadly too big to fit anywhere. I think I can make room for a three 18650 pack, so that's 11,1V. That'll be fine, right?
I probably don't need them to run on full brightness ever, and even at lower brightness I think less than an hour is okay. They're really just an effect, not something I'll have running all the time.
Can I ask you to do the maths for me here? I'm confused:
1 section contains in parallel:
3 red LEDs in series. 3*2,5V@350-450mA plus resistor1 as they will have 11,1V running through them.
3 blue LEDs in series. 3*3,7V@350-450mA
3 green LEDs in series. 3*3,7V@350-450mA

I will have three sections in parallel from the driver. The batteries are 3 18650 batteries, 11,1V total. I assume I want a resistor on the common kathode, resistor2. What values should those two resistors have?

 

Try for 100mA per LED for a start.

Series 3 x Red LEDs with a 33 ohm resistor.
Series the single Red LED with an 82 ohm resistor.

Series 2 x Green LEDs with a 43 ohm resistor.
Series a single Green LED with 72 ohm resistor.

Blue LEDs same as Green.

Use at least 1Watt resistors.

The above is not ideal but it will work ok I think.

If you go to high current, the LEDs will need to be mounted on a heat sink to cool them.

 

The battery is really the limiting factor here, decide how big it can be, and how long it must run - work backwards from there.
I think you are not going to need 350 mA LED's for this, it's massive overkill.

Buy and play with some sample LED's, trying to design this sight-unseen is a recipe for failure.

If you must have blasting brightness, then consider a PWM drive system, so you can manage the power consumption efficiently.

 

But if I only run them at 100mA, will they light up at all when they're rated 350-1000mA? The only LEDs I have found that are less than 3W are these 1W ones:

And that's basically the same as running the 3W ones at lower power. Then I would rather have the buffer and maybe have them last for longer.

dendad that's probably a good idea. How did you make those calculations? And are they for 3*18650 batteries or something else? Just so I can do it again for other currents.
I'm really sorry if I'm being stupid here, but... I guess I am.

It seems like you don't think 3 18650 batteries is a good idea here. Why is that? I know they won't last long and of course it's a bit annoying, but that's really not the most important part for me. Most important for me is the space available, the weight, the heat and whether or not they will run the LEDs as I want.

 

Is it possible to run more LEDs in series than two or three or is it a bad idea?

 

But if I only run them at 100mA, will they light up at all when they're rated 350-1000mA?

The LEDs should be plenty bright. Try one and see. It is a good exercise for you. Use a known measured voltage, like 5V, and calculate the resistor for 100mA, then hook it up to see.
Do you have a multimeter, soldering iron and other tools?

How did you make those calculations?

I used 2.6V as the forward voltage for Red. It may well be incorrect. Probably better to use 2.3V and a 42ohm resistor.

R = (11.1-(3x2.6))/0.1
R =(11.1-7.8)/0.1
33ohms=3.3Volts/0.1Amps.

Similar for the other colours. Without the LEDs so I can measure the forward voltages, it is really a guess.

It seems like you don't think 3 18650 batteries is a good idea here.

I think they will be fine, but you amay run into problems unless you can find a battery protector board for 3 cells that you can incorporate into your design. A built up pack will have that installed, at least it will if it is a good one.

 

Is it possible to run more LEDs in series than two or three or is it a bad idea?

You can run any number of LEDs in series. It is dependant on your power supply. Remember, each LED has a forward voltage drop. For example, if your LED has 2.5V forward voltage drop and you try 10 LEDS in series, your power supply will have to be over 25V to begin to run current through the LEDs.
This voltage drop is a little variable with the current through the LEDS, and temperature too.

 

Thank you, that helps a whole lot! I think I might actually be able to do a little bitps a whole lot! I think I might actually be able to do a little bit by myself now ;-P
And when I put these sections in parallel it won't change anything in these calculations, right?