Trying to run battery powered LED lights on 110V system

[nopeda]

110v led to battery

So far I would like to use some LED lights with a 110 volt inverter system because it seems they would use the least amount of power, but the only 110 volt bars of them I've seen have cost $50+ and I don't want to spent that much. I saw some that take 6 AA batteries at Walmart for a lot less. Can I use a cheap transformer to power it from a 110 volt system, and if so what voltage transformer do I need to use and do I need to solder connections between contacts where the batteries would be?

Thanks for any help!
David

 

[Audioguru]

A battery has a DC output.
LEDs need a DC input.
A transformer has an AC output that will blow up the LEDs without a rectifier to convert the AC to DC.

 

[ark5230]

What Audioguru wrote is true, however if a LED is connected to AC it will conduct during half cycle only. This could be used as an advantage while designing the LED chain and its current.
Raoof

 

[senthilkumar.b]

Hi.

You can use the 110v power source directly for this application.

as per above reply.

if we can select proper current limiting resistor,
Why not we use these leds in series parallel manner with 110v ac as per required numbers?

Its the cheapest method than buying a transformer.

Bye.

 

[Audioguru]

The max allowed reverse voltage for most LEDs is only 5V so a rectifier or connecting LEDs back-to-back should be used.

 

[senthilkumar.b]

Hi,

see the beluw diagrams and realize things.

Selected LEDs current is typically 20ma.

Current profile:





Limiting resistor power dissipation profile R=2.2k/1watt








Power dissipation on LED







Source power dissipation profile






Bye.

 

[Audioguru]

Your peak current is 20mA but the average current is about 6mA which is fairly dim.
They flicker at 60Hz.

 

[senthilkumar.b]

Above circuit is half wave rectified. the pulsed ouyput has given to the led. as per audioguru's statement, it will flicker at the rate of 60hz. but this effect cann't able to identify with bare eye such as filament bulb.

If the brightness is required, we can decrease the value of current limiting resistor. Otherwise we can use fullwave rectifier and increase the brightness almost double with the help of increasing average current value.

Note: a small value of capacitor connected parallel with DC power will further increase the stable operation.

Thanks for your comment Audioguru.

 

[Audioguru]

My LED Christmas tree lights noticeably flicker at 60Hz.

 

[Audioguru]

Duplicated post deleted.

 

[Audioguru]

Duplicated post deleted.

 

[senthilkumar.b]

Can you give the connection, signal conditioning and driver details for identyfing the route cause.

your lights are not flicker at 60hz. that shouuld be very low frequency.

Bye.

 

[Audioguru]

My mains frequency is 60Hz. My LED Christmas tree lights are half-wave rectified so they turn on and off at 60Hz and the flicker is visible.

 

[senthilkumar.b]

This is the critical upper frequency range of human eye visibility.

Now the best way for solving this issue is doubling the flickering rate(120 times/sec) by means fo providing full wave rectifier instead of half wave rectifier.

At this situation the average current value also going to be increase and spoil your LEDs. You should provide proper current limiting resistor.

Very nice Audioguru.

 

[picturelights1]

The first thing that needs to be done when connecting an LED to a battery is to consider where the LEDs will go. Batteries operating LEDs on a high wall, for example, will need to have something supporting their weight. Unless you are installing LED lights near an existing 12v battery supply, then prepare to build a ledge, box or other support for the batteries – leaving the 12v battery to dangle will eventually cause connections to break.

Locate a nearby place to put the battery, on/off switch, then measure the distance between the LEDs and the 12v battery. This is the length of wire necessary to connect the LEDs to the power supply.