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Discussion Starter #1
I have installed some awesome LED strips inside but they get random dimming fluctuations due to voltage spikes or drops from my other accessories (freezer cycling would be one I'm sure).

I am not a newbie to electrical but have never added in a capacitor where it never was before. What is the best way to wire one in to act as filter to reduce the flickers? In series with the positive feed to the LED strips?
 

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Think of a capacitor as a bucket, it holds electricity. It would have to be a very large cap to filter out fluctuations. Also I doubt you can see voltage spikes. Try this, without any devices on, engine, refrig, VHF, blah blah, see if there are any fluctuations in light output. An effective filter would be an inductor in series with a cap across the power leads. It is called a pi filter and here is a picture of one https://www.google.com/search?q=pi+filter&sxsrf=ALeKk009_Sqvz79o1q8sY4X338bNxtUdjg:1590064232463&source=lnms&tbm=isch&sa=X&ved=2ahUKEwivvfvt-sTpAhVxknIEHfG8At8Q_AUoAnoECBEQBA&biw=1352&bih=782#imgrc=Af4Fxo2t--tzfM The other thing you might try is a small switching power supply that would power the LEDs. Something like this might work https://www.ebay.com/itm/DC-DC-8-60V-To-3-32V-7A-Adjustable-Step-down-Power-Supply-Module-with-Shell-NEW/392807165667?hash=item5b7521aee3:g:kOYAAOSwDoNdw40J
 

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Discussion Starter #3
Tnx for the ideas. The fluctuations may be more evident because it's on a dimmer controller dimming by switching on an off at a specific Hz rate I'm sure.

When the freezer first fires up my house bank monitor shows the 0.3v drop or so while it spikes and the leds dim/flicker slightly for a second or two and then when it turns off they flicker again ever so slightly. My wife doesn't generally notice it but I do. There are also random other fluctuations that I see but can't tie to any one specific source of voltage change. I've heard of people using caps to act as that bucket or ballast to even out those changes.
 

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I would remove the dimmer.
I’m sure it’s already on its own dedicated breaker ( ie internal lights) . 😀
I’m also sure you have enough battery power that even when the refrigeration cycles on it would impact
The battery bank capacity😄
 

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Discussion Starter #5
I would remove the dimmer.
I’m sure it’s already on its own dedicated breaker ( ie internal lights) . 😀
I’m also sure you have enough battery power that even when the refrigeration cycles on it would impact
The battery bank capacity😄
It's on its own dedicated line separately fused and switched before the dimmer. The dimmer is key and made for 12v systems. The freezer is an engel so it spikes maybe 4ah then down to 2.5ah when running but I was just using it as an example. 4x group 27 deep cycles are the house bank. I've seen the same flicker in my OEM cabin top led lights and also in my land house when things like freezers or microwave would turn on. LEDs are very voltage sensitive compared to incandescent bulbs from what I've heard and witnessed.

Capacitors are cheap and lots of auto threads out there with the same issue but haven't found a good explanation of where to add the cap. I'll just figure it out.
 

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It's on its own dedicated line separately fused and switched before the dimmer. The dimmer is key and made for 12v systems. The freezer is an engel so it spikes maybe 4ah then down to 2.5ah when running but I was just using it as an example. 4x group 27 deep cycles are the house bank. I've seen the same flicker in my OEM cabin top led lights and also in my land house when things like freezers or microwave would turn on. LEDs are very voltage sensitive compared to incandescent bulbs from what I've heard and witnessed.

Capacitors are cheap and lots of auto threads out there with the same issue but haven't found a good explanation of where to add the cap. I'll just figure it out.
On the power supply to the LEDs. I don't know the load, but this might not be far off. The 12uH capacitance load is a small coil; ferites are often recommended (the lump you see on computer cords), but they are for radio frequencies. A coil will work much better on these low frequency fluctuations. Make it up with quick connects and you can just insert it in-line.

 

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Discussion Starter #7
On the power supply to the LEDs. I don't know the load, but this might not be far off. The 12uH capacitance load is a small coil; ferites are often recommended (the lump you see on computer cords), but they are for radio frequencies. A coil will work much better on these low frequency fluctuations. Make it up with quick connects and you can just insert it in-line.

Interesting, i had originally debated on ferrite(s) to remove noise. I do have some around and may give that a shot. Thanks
 

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Most ferrites start to attenuate above 10 Mhz so I doubt putting one in will do much good unless the dimmer is messing with your VHF. Sticking a cap across the output of the dimmer might do so good. I'd start with a cap around 120 micro-farads or so with a working voltage of 25 volts DC. Hook the plus side of the dimmer output to the plus of the cap. If you get it wron the cap will get kinda bulgy, warm then the smoke will come out. Also you want to get a low ESR cap. ESR stands for equivalent series resistance. Current goes in and out of the cap. The cap has resisance so heat is generated. The lower the ESR the less heat. Might try this one from DigiKey B41890A5127M-ND .
While you are at DigiKey might as well pick up some inductors maybe this one
AIRD-03-102K
 

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I have seen a 240ohm resister installed in a 12 volt system that was used for that same reason but not a capacitor.
 

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LEDs may be finicky, but it surprises me to hear they’d not get enough current, due to a 4 amp spike. Wonder if there is a crusty ground somewhere in the system.
 

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I don't think it is a pure voltage issue. It is related to the LED frequency-controlled dimmer and another frequency-controlled load. In the OP's case, the frequency-controlled reefer is effecting the LED dimmer.

We also have LED lights on frequency-controlled dimmers. Our 2 reefers and 1 freezer don't seem to effect them, but our waterpump, which is a frequency-controlled variable-speed type, does produce a slight flicker on one of the dimmers. Oddly, it only effects one of the three lights controlled by that dimmer.

I have suspicions that it may be related to the specific LED bulb in that fitting, because I think it is a different one than the others. However, the flickering is unnoticeable unless you are looking right at the light, and the frequency and amount of time the waterpump runs is short, so I just ignore it.

Mark
 

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Inductor, not capacitor.

Mark
Duh. Obviously (face palm).

And in case it was not obvious, I just clipped the image I posted; the 100 ohm resistance represents the down stream load, nothing more. Just an example.
 

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I don't think it is a pure voltage issue. It is related to the LED frequency-controlled dimmer and another frequency-controlled load. In the OP's case, the frequency-controlled reefer is effecting the LED dimmer.

We also have LED lights on frequency-controlled dimmers. Our 2 reefers and 1 freezer don't seem to effect them, but our waterpump, which is a frequency-controlled variable-speed type, does produce a slight flicker on one of the dimmers. Oddly, it only effects one of the three lights controlled by that dimmer.

I have suspicions that it may be related to the specific LED bulb in that fitting, because I think it is a different one than the others. However, the flickering is unnoticeable unless you are looking right at the light, and the frequency and amount of time the waterpump runs is short, so I just ignore it.

Mark
The LED itself may have some control circuitry (PWM or something) that interferes with the dimmer and/or other high frequency events on the line
 
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