LED strip works on power supply but stays solid color on battery power...why?

Thread Starter

Matt Faulty

Joined Feb 15, 2015
10
I am using a 5volt WS2812b LED strip with a 5volt mini controller. When I connect the LED strip and controller to my power supply it works flawlessly. When I connect to a 9v battery instead my LED strip lights up one solid color and the controllers buttons appear to do nothing.

I thought for some reason the voltage being so high above the strips rated value had something to do with it so I took a 7805 voltage regulator, a 10uf electrolytic cap on the + in, a 10uf electrolytic cap on the + out, and a .1uf ceramic cap on the + out to create a small voltage regulator circuit.

I tested the circuit with my DMM and with my 9v input I get a steady 4.98v output, but again the LED strip lights up one solid color. I am at a loss for why this LED strip and controller work flawlessly on my power supply feeding it 5.02v but I get this one solid color with my 4.98v battery voltage regulator setup.

Any help and insight is greatly appreciated.
 
Last edited:

bertus

Joined Apr 5, 2008
21,677
Hello,

When a circuit is designed for the use on 5 Volts, it is NOT good to connect it to 9 Volts.
Parts can be burned when you connect the circuit to a to high voltage.

Bertus
 

Thread Starter

Matt Faulty

Joined Feb 15, 2015
10
Hello,

When a circuit is designed for the use on 5 Volts, it is NOT good to connect it to 9 Volts.
Parts can be burned when you connect the circuit to a to high voltage.

Bertus
Thanks for the response. I accidentally submitted the question before finishing my explanation. I thought the same thing with supplying to much to my circuit, thought I fried it, and reconnected it to my power supply to determine it is still functional. Then I built the voltage regulator circuit, but am still facing the exact same issue.
 

bertus

Joined Apr 5, 2008
21,677
Hello,

What kind of 9 Volts battery are you using?
Is it a PP3 type?
That has a high internal resistance and the voltage will collaps as soon the current is to high.
Measure the voltage accross the battery when connected to check this event.

Bertus
 

ScottWang

Joined Aug 23, 2012
7,080
The WS2812b LED strip was made of 5050, if you using a 9V cookie battery, maybe the current will not enough and the voltage is too high.
 

Thread Starter

Matt Faulty

Joined Feb 15, 2015
10
Interesting I am reading 4.98v without the strip, but when the strip is connected its around 3.7v and appears the be continually dropping. I flipped the power switch off when it went down to 3.5v, but appeared to be still dropping.
 

Thread Starter

Matt Faulty

Joined Feb 15, 2015
10
Hello,

What kind of 9 Volts battery are you using?
Is it a PP3 type?
That has a high internal resistance and the voltage will collaps as soon the current is to high.
Measure the voltage accross the battery when connected to check this event.

Bertus
If this is the issue I'm facing, I will only be using about .3m of this 1m strip in my final project will cutting the LED strip down possibly fix this issue since there will be less current draw from the battery?
 

bertus

Joined Apr 5, 2008
21,677
Hello,

As said the PP3 batteries can not deliver much current.
Better try a block of 3 AA or D alkaline batteries without a regulator (this will give about 4.5 volts) or
4 NiMh batteries AA size ( this will give about 4.8 Volts).

Bertus
 

Thread Starter

Matt Faulty

Joined Feb 15, 2015
10
Hello,

As said the PP3 batteries can not deliver much current.
Better try a block of 3 AA or D alkaline batteries without a regulator (this will give about 4.5 volts) or
4 NiMh batteries AA size ( this will give about 4.8 Volts).

Bertus
Ok progress sorta....When I use 3AA I'm reading 4.6v but when lights are on I get around 3.5v. I connected 4AA and I'm reading 6.1v but only 4v when lights are on. With the 4AA setup the lights actually blink in sequence for maybe half a second then it goes back to the solid color again.
 

Thread Starter

Matt Faulty

Joined Feb 15, 2015
10
So I swapped out my vintage 2006 AA batteries for some fresher 2014 ones. Now on the 3AA setup I read 4.9v with LEDs off and 3.7v with them on. With the 4AA setup I read 6.4v off and 4.3v on. Similar to the 9v battery the voltage when on continually drops and when I turn the LEDs off the reading on the battery pack itself seems to creep from a lower voltage (6v in my few second test) back up to the 6.4v original reading before I turned the LEDs on.
 

Thread Starter

Matt Faulty

Joined Feb 15, 2015
10
the 1m strip draws around 1A. Since I don't need the whole 1m strip for my project I just now cut it down to about .4m and now my current draw is about .4A. It still does not want to work with the original 9v battery into a 5v regulator setup, but now it actually is functioning while connected to the 4AA batteries. I am sorta a loss however. If I am reading 6.4v across my batteries, but only 5.5v when the LEDs are on am I exposing the LED circuitry to 6.4v or to only 5.5v? Im assuming what is happening here is that the internal resistance of my AA's are causing the .9v drop and I'm only actually forcing my 5v leds to handle the 5.5v.
 

crutschow

Joined Mar 14, 2008
28,201
It won't run very long with AA batteries at that current level.
How long do you want it to operate on one set of batteries?
Going to 4 D cells will give you much longer life.
 

Thread Starter

Matt Faulty

Joined Feb 15, 2015
10
Ideally I would like a couple of hours runtime, but realistically I would be happy if I can get 30+ minutes. Im attempting to make this as light as possible. 4C or 4D batteries just isn't an option. Im guessing another type of battery other than alkaline is going to be my best bet. This project will be battered and dropped frequently. Any pointers on possible issues with different types of batteries on impact? My RC cars use NiCad batteries (again too big and bulky but maybe smaller nicads would work) and my cell phones uses a LiPo battery (never used one of these in a project), both of these seem to handle me being rough with them just fine though.

Thanks again for all the support and help.
 

ScottWang

Joined Aug 23, 2012
7,080
If you could buy some new 18650 or from second hand, that was used for the laptop, it's quite cheap, I was bought some for my portable power bank, the charger is new, but the 18650 are old.
That was made in China, the photos were copied form the website where I bought.

powerBank1.jpg

PowerBank2.jpg
 
Last edited:

crutschow

Joined Mar 14, 2008
28,201
Four AA NiMh batteries should give well over 2 hours with a 0.4A draw as they are typically rated at over 2AH capacity.

Are you sure the current is only 0.4A with the cutdown LED string?
 
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