Battery powering a long string of 5v LEDs

Stubby5000

New elf
Joined
Jan 18, 2019
Messages
2
Hello, I’m new to this forum. I’m trying to learn about 5v LEDs. Specifically, I’m trying to learn about the feasibility of powering a 5-6 meter string of 5v white LEDs with four AA batteries. My understanding is that 5v lights are more efficient compared to 12v, but the voltage drop is greater, making 5v a less than ideal choice for long strings.

Is powering a 5v string of this length even possible with batteries? How much run time could I get out of them? In my testing, I’ve noticed that running LEDs continuously from batteries eventually causes them to get dim, but then turning them off and letting them ‘rest’ a bit makes them brighter again. Can someone explain that? In my application the LEDs will be on only briefly with long periods of inactivity between. I’m hoping that works in my favor...

Any assistance would be very much appreciated. Thank you!
 

scamper

Dedicated elf
Joined
Jan 5, 2014
Messages
1,049
Location
collie
They get dim because the battery is draining and eventually go off because the power is too low. When you leave them off for a while the battery recovers slightly and works again for a short period.
Basically unless you are running very small single colour leds, then you won't be able to do it successfully.
pixel strings such as we use in this hobby draw as much as 3amps per 50 pixels. AA batteries cannot supply that.
 

Stubby5000

New elf
Joined
Jan 18, 2019
Messages
2
Sorry, I should have specified. I’m talking about an LED string like this:

Apparently URLs aren’t allowed... Put this product into Amazon to see what I’m talking about:

USB LED Strip Light White 5V 5M 300 SMD 3528 with 3M Tape for TV PC Computer Case Back Lighting,Under Counter Light (Non-waterproof, Cool White 6000-6500K,Pack of 5M)
 

Mark_M

Apprentice elf
Joined
Dec 30, 2018
Messages
94
Location
Auckland, NZ
Some store bought battery powered strings don't suffer from becoming dimmer towards the end because they run an extra cable to the end.
Refer to the image.WIN_20190118_17_21_53_Pro.jpg
 

Mark_M

Apprentice elf
Joined
Dec 30, 2018
Messages
94
Location
Auckland, NZ
Also @Stubby5000, Links are allowed but the insert link tool doesn't work. Just paste the link in the standard text box and the site will highlight it as a link.
 

scamper

Dedicated elf
Joined
Jan 5, 2014
Messages
1,049
Location
collie
That is still , I believe, 30 led's per meter and they will draw something in the vicinity of 3amps.
Unless you get the specs you are only guessing.
Have you read the acl lighting 101 manual. It explains a lot in there about power and current draw etc.
 

AAH

I love blinky lights :)
Community project designer
Joined
Dec 27, 2010
Messages
3,388
Location
Eaglehawk
The ability to add url's is an anti-spam measure for new members.
https://www.amazon.com/Computer-Lighting-Counter-Non-waterproof-6000-6500K/dp/B01G572CAW/
In 1 of the answered questions is the current for the full 5m strip and it's 4A for the strip.
If you run direct from 4 AA batteries of alkaline type then the voltage initially will be about 5.6V and the current will be about 5A and with a rating of 2500mAH you will get maybe 1/2hr use. If using from 4 AA NiMH batteries the voltage will be more like 5.2V and with 1400mAH batteries you'll get maybe 20-25 minutes due to the lower voltage and current.
If you are set on using 4 AA batteries and that strip and you could live with lower brightness as it's possible the strip is quite bright then the use of a small switchmode regulator like https://www.aliexpress.com/item/Ultra-Small-Size-DC-DC-Step-Down-Power-Supply-Module-3A-Buck-Converter-Adjustable-1-8V/32880983608.html and using an output voltage of about 3.3V will extend the battery life massively.
To compensate for voltage drop it's possible to connect to the middle of the strip so that the 2 ends only have 1/2 the voltage drop of a full length strip.
 

JPB

Full Time elf
Joined
May 13, 2010
Messages
338
Location
Glenwood
For my wireless Santa hats I found a power bank gave a better life than AA batts.
Use a normal USB cord and just connect the power wires.
Jon
 
Top