#### dyudkin

Joined Feb 8, 2021
14
Hi everyone, I'm new to electronics and could really use the help of some experts.

I'm designing a mobile light-up octopus. The tentacles are about 6 feet each, and I want each tentacle lit with an LED strip. I want a central battery-driven power source.

In other words, I am trying to put together 8 LED strip lights, run in parallel, connected to a central battery-powered power source. The source needs to last for 8 hours.

I don't know where to start in terms of procuring the appropriate equipment. The ideal answer to this post would provide an answer to the following:
a) What is the most appropriate power supply?
b) What sort of splitter/converter should I use?
c) What make/brand LED lights should I purchase?
d) Precise instructions for a beginner for what will be needed to assemble these materials. I can solder etc. with precise instructions if necessary.

Super high-quality items not necessary; budget hardware will do.

#### Sensacell

Joined Jun 19, 2012
2,819
This becomes a bit of a circular problem. 8 hours is a long time.

You may need to accept reduced brightness and / or low density of lamps to meet this requirement - unless you have room for a big fat heavy battery.
You need to define the problem a bit more before you can tackle it.

Try to define the acceptable light solution first- so you can get some numbers for how much power this octopus needs, then you can work out a power solution.

Buy a few samples of LED strips- test them out to see if they are bright enough- then post your findings along with the specifications of the lights you bought.

#### dyudkin

Joined Feb 8, 2021
14
I don't know enough about light to be able to define the light solution any better than I have, unfortunately. But I'll say this: if I need to purchase a car battery, for instance, so be it. I can do that.

#### Sensacell

Joined Jun 19, 2012
2,819
I don't know enough about light to be able to define the light solution any better than I have, unfortunately. But I'll say this: if I need to purchase a car battery, for instance, so be it. I can do that.
Fine- but you need to start somewhere.

A car battery is 12 Volts- buy a few 12volt LED tapes and experiment- there are many available.

Joined Jan 15, 2015
5,934
Just as an example and there are so many LED strips out there it's hard to choose but consider your application and things like weather proof or non weatherproof.

Using this example:

They come in 12 or 24 volt strips and I will choose 12 volts. Running at 12 volts I figure 3.0 watts / foot. (A little over included actually 2.9 Watts / Ft.) ). Tentacles at 6 feet times 8 tentacles = 144Watts. Each tentacle is 6 feet times 3 watts per foot so about 18 watts per tentacle times 8 tentacles equals 144 watts. Now at 12 volts that becomes 144 Watts / 12 Volts = 12 Amps but lets call it at 15 amps to leave some headroom. 15 Amps at 8 hours would be a 120 Amp Hour 12 VDC battery. That is a large battery depending on battery chemistry. Something like a deep discharge RV battery.

Again, your choice as to LEDs to use. Things like color or waterproof? My example used warm white non waterproof or water resistant. Anyway battery will be based on your LED choice.

Ron

#### Audioguru again

Joined Oct 21, 2019
3,171
If you make a circuit blink the LEDs on and off the current will be half and the battery size will also be half.
If you make each blink a short duration then the current and battery size will be much less.
A blink duration shorter than 30ms (0.03 seconds) appears to be dimmed. 30ms or longer appears at full brightness.

#### dyudkin

Joined Feb 8, 2021
14
All of this is already super helpful. I don't know enough about electricity to be able to do the math (i.e., I don't know when the numbers are additive or multiplicative), so seeing an example of the calculations helps.

If I buy a car battery, do I need a special adapter to connect it to the LEDs?

Definitely waterproof LEDs. Are there strips whose length can be customized (cut to length)?

Should I buy LED splitters, like this?

If I want blinking LEDs, do I need to get a separate blinking mechanism or will the strips have that setting?

ANY THOUGHTS/INFO APPRECIATED I AM STARTING AT ZERO

#### Bernard

Joined Aug 7, 2008
5,788
Another choice is ' Neon like LED strip' . About .6 amp per meter @ 12V. 2 X 8 X .6 X 8 hr. = 76.8.
A hr. Maybe something like a motor cycle battery ? It can be cut on marks, is water resistant & illustrations on U tube. Carried by several distributers like Digi Key, Mouser . I would use a terminal strip to connect all in parallel with a fuse & switch.

#### dyudkin

Joined Feb 8, 2021
14
Another choice is ' Neon like LED strip' . About .6 amp per meter @ 12V. 2 X 8 X .6 X 8 hr. = 76.8.
A hr. Maybe something like a motor cycle battery ? It can be cut on marks, is water resistant & illustrations on U tube. Carried by several distributers like Digi Key, Mouser . I would use a terminal strip to connect all in parallel with a fuse & switch.
Very helpful....just to make sure I understand what you have in mind would you be able to send an example link or two?

#### dyudkin

Joined Feb 8, 2021
14
Very helpful....just to make sure I understand what you have in mind would you be able to send an example link or two?
I get the neon strip but examples of the "distributor"....I don't know what that is.

Joined Jan 15, 2015
5,934
If I were you I would be looking towards bare bones LED strips and meaning no whistles and bells like an included power supply. In my earlier example I chose a simple 12 VDC powered string simply because 12 VDC batteries are common. A 12 VDC lead acid chemistry battery is very common and actually about 12.6 volts but 12 volts is close enough. The idea is to power your project and then some or I used the word overhead. In my example I ended up with a 12 VDC 120 AH (Amp Hour) battery.

It will always come back to you choosing LED strips that provide the visual effects you want. Give yourself a few parameters and work from there in selecting what works for you. The distributor is merely where you buy the end result from. Just about all the sluff is made in China and comes in through various importers who pass it along to various distributors. Now on that note try to shop wisely. Using Amazon for example you can find 1/2 dozen prices for the same item. Try to find any positive reviews of LED Strips you feel would work for you.

Ron

#### djsfantasi

Joined Apr 11, 2010
7,689
Using Amazon for example you can find 1/2 dozen prices for the same item.
And depending on the price, a dozen strips may be cheaper than eight strips. You can keep the extras as spares or use them in multiple octopi.

#### dyudkin

Joined Feb 8, 2021
14
And depending on the price, a dozen strips may be cheaper than eight strips. You can keep the extras as spares or use them in multiple octopi.
Very helpful! So from this I'm gathering that it won't necessarily be terrible quality if I purchase through Amazon, provided the reviews are positive. This means I don't necessarily need to purchase through a specialized distributor. I've also gleaned that the type of power provided by a normal 12V battery will be compatible with a 12V LED strip. So as long as the voltage is roughly equivalent I don't need to worry too much about compatibility issues. The biggest next question then would be whether any special devices will be needed to A) convert the power supply from the battery to the LEDs, and B) what approach I should use to be "splitting" the current to run the strips in parallel.

Joined Jan 15, 2015
5,934
Very helpful! So from this I'm gathering that it won't necessarily be terrible quality if I purchase through Amazon, provided the reviews are positive. This means I don't necessarily need to purchase through a specialized distributor. I've also gleaned that the type of power provided by a normal 12V battery will be compatible with a 12V LED strip. So as long as the voltage is roughly equivalent I don't need to worry too much about compatibility issues. The biggest next question then would be whether any special devices will be needed to A) convert the power supply from the battery to the LEDs, and B) what approach I should use to be "splitting" the current to run the strips in parallel.
No, the whole idea behind a 12 volt power source and 12 volt LED strip is to avoid the need for anything special. Since you are not after changing colors and fade in, fade out routines things remain pretty simple. To get right down to it and using an octopus as an example there are endless schemes for the tentacles. If all I want is an octopus with his (or her) tentacles illuminated in a constant white like a warm white everything is simple. Now if I start adding features like fade in and fade out lighting things start to get more complex and the more features I add the more complex things become to a nightmare point.

Ron

#### djsfantasi

Joined Apr 11, 2010
7,689
and B) what approach I should use to be "splitting" the current to run the strips in parallel.
As Ron said, by using 12V strips and. 12V battery, you don’t need anything to “convert” the power supply.

Nothing too difficult to “split the current”. Simply wire all the LED strips + connections to + of the battery... Same for the - connections. This may be all you need.

To switch them on and off, wire a SPST (single pile single throw) switch (rated for the total current) in series between the LED strips + and the battery +.

If you want to control the lights with a microprocessor or other electronics, you can replace the switch with a relay (or something electrically similar). If you’re interested, we can supply more detail on this option.

#### Bernard

Joined Aug 7, 2008
5,788
I see that 2m, 6.5 ft., lengths of neon-like strips are available like Amazon- JINHODY. Mixed reviews.

#### dyudkin

Joined Feb 8, 2021
14
As Ron said, by using 12V strips and. 12V battery, you don’t need anything to “convert” the power supply.

Nothing too difficult to “split the current”. Simply wire all the LED strips + connections to + of the battery... Same for the - connections. This may be all you need.

To switch them on and off, wire a SPST (single pile single throw) switch (rated for the total current) in series between the LED strips + and the battery +.

If you want to control the lights with a microprocessor or other electronics, you can replace the switch with a relay (or something electrically similar). If you’re interested, we can supply more detail on this option.
Thank you, yes...I'm very interested in light-pattern options. Honestly if all that I had was blinking (say, .5 seconds on, .5 off) that would be fine. I know that some LED lights come with pattern-customization built in. But on this configuration, would I need to get a separate device? Would I be able to get an SPST that accommodates this?

#### djsfantasi

Joined Apr 11, 2010
7,689
(somehow my response was missing a huge portion)
(screwed up again. One more edit)

Adding flashing can be done by wiring a flashing module in series with the power, just like the switch.

The decision is to build or buy. I hinted at this above, when I suggested using a BJT/MOSFET in the switch location, driven by electronics. You could build a 555 based timing circuit to drive the transistor switch.

But, I suspect that this may be a strain on your skills. Even if we supply a solution, can you read a schematic, wire ICs, transistors, resistors, capacities and relays? Even simpler, can you solder?

Or, you can buy a flasher module. One which has selectable patterns and is used to drive LED lights, can cost you $30-$40. Or an automotive flasher relay used in turn signals can be used at a cost of $10-$20. If the flashing rate is acceptable.

The ultimate solution which you can ignore is microprocessor based. Someone else may suggest it, but then you add on a learning curve for programming and uploading your program. I don’t recommend this solution for you.

If any of these ideas appeal to you, let me know. Then I can provide more detail.

Last edited:

#### dyudkin

Joined Feb 8, 2021
14
The ultimate solution which you can ignore is microprocessor based. Someone else may suggest it, but then you add on a learning curve for programming and uploading your program.

If any of these ideas appeal to you, let me know. Then I can provide more detail.
Your suggestions above (12V strips, 12V battery) with SPST sounds like exactly the right solution, so YES this idea is very appealing and I'd love to hear details if you'd care to provide them!

#### djsfantasi

Joined Apr 11, 2010
7,689
Your suggestions above (12V strips, 12V battery) with SPST sounds like exactly the right solution, so YES this idea is very appealing and I'd love to hear details if you'd care to provide them!
My post got all screwed up! Re-read the updated version and get back to me.