Why do LED lights sometimes flicker?

A place to post images and descriptions of your OutBack Power System

Moderators: OutBack Moderator Team, OutBack

Post Reply
pioneerMan
Forum Virtuoso
Posts: 99
Joined: Wed Jan 09, 2019 3:40 pm
My RE system: 12 volt system
26 lead acid batteries, 6V, each rated at 210 amp hours
12 solar panels (Mitsubishi 125 Watt)
Outback VFX2812 inverter and two FLEXmax 60 inverters
Trimetric 2030A battery monitor
Mate 3d
Dual fuel 4500 watt AC generator
Location: Northern Utah

Why do LED lights sometimes flicker?

Post by pioneerMan »

The Outback inverter we have supposedly produces a pure sine wave. If that is the case, why do my LED lights flicker? It's so annoying sometimes that I just turn off the lights.

Thank you.
706jim
Forum Whiz
Posts: 40
Joined: Tue Apr 28, 2020 10:52 am
My RE system: 6x330 watt Canadian solar panels 8x370 ah Trojan L16's Flexmax 80 Trace DR1524 Msw

Re: Why do LED lights sometimes flicker?

Post by 706jim »

I know that if you take a string of Christmas tree lights and wave them back and forth you can easily see them turning on and off rapidly. Maybe all LED's do this?
raysun
Forum Emperor
Posts: 4554
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A, (2) FM80, MATE3s, FlexNetDC
SimpliPhi 48-3.8 (6 @ 48v)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
Honda EU7000is gas fuel generator

Re: Why do LED lights sometimes flicker?

Post by raysun »

pioneerMan wrote: Thu Jan 07, 2021 3:14 pm The Outback inverter we have supposedly produces a pure sine wave. If that is the case, why do my LED lights flicker? It's so annoying sometimes that I just turn off the lights.

Thank you.
We installed inexpensive LED ceiling lights and found out one reason they are cheap is because the driver circuits and emitters are cheap. They flicker at times, especially if used with a dimmer. Other times, they seem to be impacted when motors/compressors are running.
pioneerMan
Forum Virtuoso
Posts: 99
Joined: Wed Jan 09, 2019 3:40 pm
My RE system: 12 volt system
26 lead acid batteries, 6V, each rated at 210 amp hours
12 solar panels (Mitsubishi 125 Watt)
Outback VFX2812 inverter and two FLEXmax 60 inverters
Trimetric 2030A battery monitor
Mate 3d
Dual fuel 4500 watt AC generator
Location: Northern Utah

Re: Why do LED lights sometimes flicker?

Post by pioneerMan »

raysun wrote: Thu Jan 07, 2021 3:24 pm We installed inexpensive LED ceiling lights and found out one reason they are cheap is because the driver circuits and emitters are cheap.
Has anyone found a brand of LED light that is higher quality? So far I've been using these amber bulbs because they block more of the blue light emitted by regular LED lights. Dr. Mercola says the blue light is damaging to the eyes especially at night time.

https://www.walmart.com/ip/Great-Value- ... /155153029
User avatar
EA6LE-ONE
Forum Guru
Posts: 497
Joined: Tue May 05, 2020 7:51 am
My RE system: System 1:
MATE3s, 3 x Radian GS8048A,
6 x FLEXmax 100, HUB10,
2 x EnergyCell 48V 2700RE,
1 x FLEXnet DC, 6 x FLEXware ICS Plus,
78 x PANASONIC VBHN325SA17 325W

System 2:
MATE3s, Radian GS8048A,
2 x FLEXmax 100, HUB10
1 x EnergyCell 48V 2700RE,
1 x FLEXnet DC, 2 x FLEXware ICS
21 x PANASONIC VBHN325SA17 325W
Location: Providenciales, Turks & Caicos Isl.

Re: Why do LED lights sometimes flicker?

Post by EA6LE-ONE »

I have some led lights like that and they do blink while dimmed. there are some special dimmers that reduce the flicker but they are expensive. the led lights do flicker when a significant load starts. the dimming also amplify that flicker. have some led lights that are dimmed to lowest and they almost go off for a fraction of second sometimes.
fcwlp
Forum Czar
Posts: 791
Joined: Wed Jan 22, 2020 9:40 am
My RE system: GS8048A, FM80 w/3,600W PV Fixed, FM80 w/2,700W on Zomeworks tracker, Mate3, 24 Trojan 2V L16 1100AH @ C20, Grid-Tied with Kohler 14RESA LPG Generator and MEP-803 Diesel if needed.

I install and maintain grid-tied and off-grid systems in my area and consult on solar system design/operation.
Location: 80 miles NE of Phoenix at 5500'

Re: Why do LED lights sometimes flicker?

Post by fcwlp »

raysun wrote: Thu Jan 07, 2021 3:24 pm We installed inexpensive LED ceiling lights and found out one reason they are cheap is because the driver circuits and emitters are cheap. They flicker at times, especially if used with a dimmer. Other times, they seem to be impacted when motors/compressors are running.
@raysun has it correct. I have worked with with a number of the LED companies in the past. Based on my experience I only use Philips or Cree LED lights and have no flickering issues. I also trust their quality control. If you do use a dimmer, you must make sure it is for LED lights and has been tested for the specific LED light model.
Last edited by fcwlp on Fri Jan 08, 2021 10:26 am, edited 1 time in total.
provo
Forum Czar
Posts: 719
Joined: Thu Jul 27, 2006 4:34 pm
My RE system: Sixteen Evergreen EC-120
(4 strings, total 1920W)
Eight Rolls S-550 (2 strings, total ~800Ah @ 24V)
One FM80
One VFXR3524A
Hub 10
Mate3s
FNDC and Trimetric
Honda EU3000is generator
Location: Sierra foothills

Re: Why do LED lights sometimes flicker?

Post by provo »

pioneerMan wrote: Thu Jan 07, 2021 8:20 pm
Has anyone found a brand of LED light that is higher quality?
I like these, partly because I can get them in 5000°K color, and partly because of the radiating ribs. A lot of my fixtures are fully enclosed, and if they don't have ribs they die quicker.

TCP dimmable.jpg
sbrownian
Forum Czar
Posts: 538
Joined: Mon Nov 30, 2020 9:23 am
My RE system: GS8048 FM80 FNDC Mate3
4kw solar
7kw Kubota propane gen
Had 1200 Ahr FLA Locomotive batts
Just replaced with
2 x 300 Ah ReLion Lithium packs
MUCH more efficient!!
Location: Central Washington State

Re: Why do LED lights sometimes flicker?

Post by sbrownian »

706jim wrote: Thu Jan 07, 2021 3:16 pm I know that if you take a string of Christmas tree lights and wave them back and forth you can easily see them turning on and off rapidly. Maybe all LED's do this?
LEDs are -DC- powered devices.

Most of the time, the flicker is due to poorly designed, (read cheap @ssed,) power supplies that do just half wave rectification that results in pulsed DC feeding the LEDs. (The el cheapo Christmas lights.)

The higher end products have actual switching power supplies that turn the AC into high voltage DC and then 'chop' that using variable duty cycle switching elements. The resulting high frequency pulses are fed into filters that smooth out those pulses into fairly clean DC that goes to the LEDs.. (I haven't seen linear power supplies used for this type of application in literally decades.)

A less expensive methods is to >not< really filter it much at all as that switching frequency is a lot higher than what you can perceive.

As an interesting side benefit of that, they have found that you can actually place information IN that pulse stream and have devices 'read' that and transfer data via the visible light. (Shades of TEMPEST, anyone?)

Old timers (me included,) will remember infrared networking file transfer ports on early laptops...

The reason for specifying LED rated dimmers has to do with the way the old dimmers work. They basically have an SCR or TRIAC circuit that 'waits' until the AC waveform gets partially thorough the cycle and then switches on, letting the remainder of that part of the cycle 'through' to the light. The thermal delay, or 'ballistics' of a tungsten element is long enough to smooth out the resulting pulses of AC power.

That loss of energy between pulses can excede the ability of the LED power supply filter it out, cause instability issues, or just plain not deliver enough voltage for the power supply to work.

Look up AC rectification and TRIAC light dimmers for more info.
Information, you get not; if incorrect question, you ask..
Post Reply