question

wandering-albatross avatar image
wandering-albatross asked

Multiplus causing Dimmable LEDs to Flicker

Recently installed a 12v Multiplus (3000 VA) system with lithium batteries, mppt, DC-DC chargers, etc. into a motorhome.

Core functionality works great. When the inverter is under high current, such as running the AC off the batteries, all of the dimmable LEDs flicker.

To clarify, the flickering is only the dimmable LEDs that are partially dimmed. If the dimmable LEDs are turned up all of the ways, the flickering does not occur. This is happening in three different locations with three different dimmable LED bulb brands (one is a 6ft light strip). Other non-dimmable LEDs show no such problem either.

I measured the voltage for the different lighting circuits and I am getting 13v when there is about a 1.5kw load on the inverter. I tried other high loads such as the microwave and it behaved similarly. Once the load is reduced to 100w or 200w, the flickering seems to go away.

There is a ton of copper wire in the system including 4/0 cables for the 12v supply to the inverter.

Also, I fired up the old 12v lead acid converter and it could power the dimmable LEDs without issue. No flickering off the original AC-DC converter.

Questions:

1) Could this be an interference issue between the power cables? I have the 4/0 DC and 30 amp AC wires fairly close to entering the cargo bay?

2) Could it be a chassis ground issue? My inverter ground goes to the battery bank and chassis. Maybe the chassis ground is not sufficient?

3) Do I need to get ahold of an oscilloscope and do an FFT on the signal? Could ferrite beads help?

Any trouble shooting suggestions would be much appreciated. Thanks!

multiplus ve.bus
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

11 Answers
wkirby avatar image
wkirby answered ·

It's difficult to answer because it's not certain what's happening or how the LED driver is constructed.
I doubt it's any type of interference in the cables that any sort of filtering could fix.
It seems to me that reactive loads are causing distortion of the AC sinewave that the LED driver is particularly sensitive to. This sort of distortion is inevitable with a reactive load on a microgenerator which has a relatively small output transformer compared to a substation or pole transformer.
A lot of the time these LED drivers are built to a price and will work only in absolutely perfect conditions. The drivers themselves are probably chopping the sinewave for dimming and introducing even more distortion.

I'd be interested to find out what brand or model of LED strips you are using and get some myself. Then analyse them and figure out what's going on exactly and perhaps find a way to solve the problem.

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

wandering-albatross avatar image
wandering-albatross answered ·

The LEDs are 12v and are dimmable T4s and a dimmable light strip from Boogie Lights. No Boogie Light controller, just an inline dimmer.

If I am connected to shore power and the inverter is in passthrough mode, I don't have the flickering issue. The main load is 120v in and 120v out. It only seems to occur when I am pulling hard on the 12v battery bank with a large inverter load (~50 amps and above).

I am planning to double check my chassis ground. Anything else I should take a look at?

Thanks!

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Kevin Windrem avatar image
Kevin Windrem answered ·

Some dimmers are very sensitive to the DC voltage and even a few tenths of a volt can make a huge difference. I tested several dimmers and ended up with the type that has a separate positive and negative source and separate positive and negative load connections. The "in-line" types were much more apt to flicker especially at low brightness settings, sometimes even without any DC loads on the system.

Make sure your inverter is connected to the battery (or the shunt) without using the chassis connection to avoid any chassis-related voltage drops. In fact minimizing any chassis current with negative "return" wires for all circuits is a wise goal.

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

jw1971 avatar image
jw1971 answered ·

Try bypassing the dimmer and powering LED directly - does it flicker? Then you know if the dimmer is really the culprit.

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

wandering-albatross avatar image
wandering-albatross answered ·

Yeah, I have 4/0 wire for both positive and negative between the inverter and the batteries. I also have a chassis ground off the main bus bars.

Can you please provide an example of the dimmer that you found to work under 12 loads? It sounds like you have experienced the same issue as I am working through now. I believe my current dimmer would be considered an "in-line" type.

If I turn the dimmer to the brightest setting, all of the dimmable LEDs work fine even under load. The issue goes away. If the batteries are under load AND the LEDs are partially dimmed, then the flickering shows up.

Thanks.

1 comment
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

kevgermany avatar image kevgermany ♦♦ commented ·
Might be worth checking battery capacity as well.
0 Likes 0 ·
Kevin Windrem avatar image
Kevin Windrem answered ·

I am using these:

https://amazon.com/gp/product/B01C4UBMY6

When I wired these in-line the lights would flicker at certain brightness but when wired in a 3-wire configuration with a separate negative wire for the supply, they are much more stable

https://www.amazon.com/gp/product/B072349JZN

This has separate line and load wires for both positive and negative.

I should note that the LEDs still flicker a bit. I have multiple lights on one dimmer and some of the lights flicker while others on the same dimmer do not.

The flickering I experienced had nothing to do with my Multi Compact so this may or may not help.

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

wandering-albatross avatar image
wandering-albatross answered ·

Do you think this DC-DC stabilizer might work?

1 comment
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Kevin Windrem avatar image Kevin Windrem commented ·
It probably would if it's DC voltage variation that is causing the flicker.
0 Likes 0 ·
Bruce Fergusson avatar image
Bruce Fergusson answered ·

When troubleshooting I start with the basics. You mentioned ground path - I would learn about single point ground systems, aka. star grounds, ground window, etc. (https://hennulat.wordpress.com/2012/04/28/grounding-and-bonding-best-practice-wired-star-grounding/ is one piece to start. If the battery return path is shared, then ”ground” is no longe at zero potential

This may or may not be not the problem, but rule out the easy stuff first

Good luck!

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

wandering-albatross avatar image
wandering-albatross answered ·

Thanks for the tips regarding the ground path.

I tried the DC stabilizer and it did seem to cure the issue. The dimmed LED does not flicker while the inverter is under higher loads. So far I have tested it on the light strip.

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

jadkins avatar image
jadkins answered ·

Can you share which stabilizer you used?

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

sharpidea avatar image
sharpidea answered ·

Phillips makes a flicker-free led light bulb that solves this issue for regular kitchen floods

https://www.amazon.com/dp/B07C3YLLTM?psc=1&ref=ppx_yo2ov_dt_b_product_details

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Related Resources

Additional resources still need to be added for this topic