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

Discussion in 'The Projects Forum' started by Matt Faulty, Feb 15, 2015.

  1. Matt Faulty

    Thread Starter New Member

    Feb 15, 2015
    10
    0
    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: Feb 15, 2015
  2. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,347
    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
     
  3. Matt Faulty

    Thread Starter New Member

    Feb 15, 2015
    10
    0
    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.
     
  4. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,347
    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
     
  5. crutschow

    Expert

    Mar 14, 2008
    13,028
    3,237
    Are you getting 5V from the regulator when the LEDs are connected?
     
  6. ScottWang

    Moderator

    Aug 23, 2012
    4,855
    767
    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.
     
  7. Matt Faulty

    Thread Starter New Member

    Feb 15, 2015
    10
    0
    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.
     
  8. Matt Faulty

    Thread Starter New Member

    Feb 15, 2015
    10
    0
    It is a pp3 type 9v and yes the voltage across it drop from 9v way down to around 6v when the circuit is turned on
     
  9. Matt Faulty

    Thread Starter New Member

    Feb 15, 2015
    10
    0
    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?
     
  10. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,347
    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
     
  11. Matt Faulty

    Thread Starter New Member

    Feb 15, 2015
    10
    0
    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.
     
  12. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,347
    Hello,

    Are the batteries fresh?
    Older batteries will get higher internal resistance.

    Bertus
     
  13. Matt Faulty

    Thread Starter New Member

    Feb 15, 2015
    10
    0
    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.
     
  14. crutschow

    Expert

    Mar 14, 2008
    13,028
    3,237
    How much current does the circuit take?
     
  15. Matt Faulty

    Thread Starter New Member

    Feb 15, 2015
    10
    0
    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.
     
  16. crutschow

    Expert

    Mar 14, 2008
    13,028
    3,237
    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.
     
  17. #12

    Expert

    Nov 30, 2010
    16,321
    6,818
    The voltage you measured is the voltage the LEDs are using.
    Trying to get an amp out of a battery requires at least size C.
     
  18. Matt Faulty

    Thread Starter New Member

    Feb 15, 2015
    10
    0
    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.
     
  19. ScottWang

    Moderator

    Aug 23, 2012
    4,855
    767
    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: Feb 15, 2015
  20. crutschow

    Expert

    Mar 14, 2008
    13,028
    3,237
    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?
     
Loading...