LED 12v circuits

[Kittyhawk]

In my motorhome all the lights are 12v LEDs.
I want to reposition a couple of the lights and on opening up the panels on which they are mounted see that on the 12v feeds, just before the lights there is a small PCB with 'CSA' written on them. An internet search revealed two options for CSA - Current Sensing Amplifier and Community Supported Agriculture. I figured the former was the most likely one in my application so looked a bit more online. Electronics is a black art to me but from what I understand, a CSA senses the current delivered to a device. It doesnt do anything about it, it just senses it. But presumably it must do something other that that. Can anyone advise please?

 

[imageel]

A couple of photo of the PCB - both sides may help identify.
LED's are usually constant current devices and the voltage required is determined by the configuration of the LED module itself - these days a lot of lights comprise a number of LED's in a series/parallel so the operating voltage will vary across different configurations.
If you simply wish to relocate them if you can identify the switched input side which will be 12V then can you not just reposition the LED light itself and the PCB that is performing the current limiting and if necessary just extend the wires on the input side?

 

[Kittyhawk]

Thanks for your reply.
The job is done already, lights shifted and working fine so can't photograph. The PCB's were enclosed in shrink wrap which I had to remove in order to unsolder and resolder the feed wires for the new location. I also replaced the shrink wrap.
Written on the original shrink wrap cover was LR209028 CSA 125°C. The PCB's are about 30mm long, 10mm wide, a heavy wire donut shaped coil at each end and a number of little black square things inbetween. My electronic ignorance is on display.
There is no problem with any of it - the lights are all reinstated in their new positions and working. I didn't have these little PCB's in tandem with the LED lights in boats I've owned in the past and I wonder what their purpose is.

 

[imageel]

It may be the LED's in your boats had the electronics built in as do mains powered GU10 downlights etc. The components you describe are likely an inductor and associated devices that switch the input voltage at high frequency to control the likely lower voltage and constant current the LED's require - commonly called a constant current buck converter. They use these types of circuits because they are more efficient than conventional series type regulators which have to dissipate as heat the product of the excess voltage and whatever operating current the LED's require.

 

[Kittyhawk]

Yes, that makes sense. I recall the LED lamps in the boats had aluminium finned heat sinks behind them - the ones in the motorhome do not. A good explanation and I've learned something new. Thank you

 

[imageel]

Led's themselves are very heat sensitive and usually in these types of light where it may comprise 20+ leds mounted in a small space, the PCB the leds are mounted on itself has a thick aluminium heat spreader and the external housing is then finned to allow air convection to dissipate the heat.
It may be that the ones in your motorhome are of a newer more efficient design that means the devices can dissipate the smaller amount of heat without requiring external fins.

 

[paulrbarnard]

Thanks for your reply.
The job is done already, lights shifted and working fine so can't photograph. The PCB's were enclosed in shrink wrap which I had to remove in order to unsolder and resolder the feed wires for the new location. I also replaced the shrink wrap.
Written on the original shrink wrap cover was LR209028 CSA 125°C. The PCB's are about 30mm long, 10mm wide, a heavy wire donut shaped coil at each end and a number of little black square things inbetween. My electronic ignorance is on display.
There is no problem with any of it - the lights are all reinstated in their new positions and working. I didn't have these little PCB's in tandem with the LED lights in boats I've owned in the past and I wonder what their purpose is.

The code is actually for the heat shrink…

 

[Spectric]

This is where savings can be made in the home, especially where people are using solar panels. Currently solar panels produce low voltage Dc, invertor takes it up to 230 vac and then your LED bulbs take it back down to low voltage. It has to be more efficient to have just a low voltage circuit with low voltage LED lights.

 

[pe2dave]

This is where savings can be made in the home, especially where people are using solar panels. Currently solar panels produce low voltage Dc, invertor takes it up to 230 vac and then your LED bulbs take it back down to low voltage. It has to be more efficient to have just a low voltage circuit with low voltage LED lights.

Which makes it surprising that some installations don't use the lower voltage for e.g. house lighting.
I've certainly never heard of it.

 

[imageel]

Which makes it surprising that some installations don't use the lower voltage for e.g. house lighting.
I've certainly never heard of it.

The mains powered GU10 style lamps have a super-cheap cct contained in the bases that does the job of rectifying then stepping down and current limiting the output. These obviously are built to a cost and are likely the thing that fails when the LED eventually dies, however the designs improve over time and they now have a reasonable level of reliability and longevity however are likely still way short of the actual LED's useful lifetime.
Even the retro style 'filament' led bulbs in conventional glass envelopes contain this cct in their bases.
The useful led lifetime is usually measured as a % of light output compared to when new, and this reduction is down to a similar effect one used to see with fluorescent tubes - where the phosphors age and colour drift and dim - a lot of current led modules use a similar tech - deep blue /near UV LED's and a usually yellow in colour phosphor coating that fluoresces when excited by the LED. Using this tech allows better control over the colour temperature and the CRI and also facilitates the ability to dim them albeit it adds to the challenges of the minimum 'on' value where it takes a minimum level of current to get the LED to start illuminating as well as a similar minimum to get the phosphor to start fluorescing.

 

[Dabop]

This is where savings can be made in the home, especially where people are using solar panels. Currently solar panels produce low voltage Dc, invertor takes it up to 230 vac and then your LED bulbs take it back down to low voltage. It has to be more efficient to have just a low voltage circuit with low voltage LED lights.

Actually, in most cases the solar panel voltages are much higher than the mains voltages- panels can vary between 30v to nearly 100v depending on the manufacturer, and almost all installations are series or series parallel...

These panels for example are over 80vdc output per panel...

Gridtie inverters are usually at least 300v, with many inverters handling up to 600vdc inputs- even many offgrid systems are in the hundreds of volts range...
(my own inverter a 12kw hybrid being used exclusively offgrid- has a 250vdc voltage limit on its dual inputs...) which means running 5 of my 38v panels in series...

 

[Dabop]

Which makes it surprising that some installations don't use the lower voltage for e.g. house lighting.
I've certainly never heard of it.

Actually- quite common in offgrid houses- these are the LEDs I use here for example (they actually cost less than 'normal' 230vac ones when buying them by the box!!!)

Look like 'normal' 230vac LEDs, but run on 12v to 85v AC or DC- so perfect for 12v, 24v, 48v or 72v battery banks- I got ES only because I had a box of ES bases left over from another job, they come in BC as well, and there are 'downlight' ones available as well... they run directly from my battery bank...

You can't use them on 96v or 120vdc battery banks (more common in newer offgrid installs) but for those US style '110vac' ones work just fine on DC- although finding those in BC bases is difficult...

The 230v powerpoints run from the inverter, but the LED lights run directly from the battery bank...
(you wouldn't know it unless you looked at the writing on the bulb however)

 

[Kittyhawk]

The code is actually for the heat shrink…

I don't think it is.
Here a pic of some little gizmo bearing the same markings as the PCB in the line just before my LED light. I find this code on similar devices on the internet and it is referred to as a LR209028 CSA Litelfuse. None the wiser as to why it is in each circuit immediately before each LED lamp. There are two lighting circuits through the truck with their own fused circuit breakers.

 

[paulrbarnard]

I don't think it is.
Here a pic of some little gizmo bearing the same markings as the PCB in the line just before my LED light. I find this code on similar devices on the internet and it is referred to as a LR209028 CSA Litelfuse. None the wiser as to why it is in each circuit immediately before each LED lamp. There are two lighting circuits through the truck with their own fused circuit breakers.View attachment 173284

The numbers turn up in a lot of places
Baomain Heat Shrink Tube Shrinkage Ratio 2:1 1mm Dia 125℃ 600V UL CSA 5 Meter Black Amazon.com

 

[Dabop]

It is definitely the heatshrink coding lol

Unless your devices come in 5m rolls with no electronics inside them...

 

[Dabop]

Interesting- I found the original ad at 100outlets.com- and they indeed list the heatshrink labels as the part number LOL- but the Littelfuse number they have listed (and the part description ie LittelFuse Telecom Fuse- matches nothing available at the Littelfuse website... the part number given (BU1606-084) isn't one of their part numbers, and the Telecom fuses they have are nothing like that shown at that 100outlets website...
Me thinks they are a scam...

(which wouldn't be surprising considering the source...)

​

As for what (if anything) is actually inside that heat shrink- anyone's guess....