12v COB LED - Driver needed?

[Parabola]

Hi,

I've bought x4 1m lengths of 12v COB LEDs from one of the well-known Chinese sites.

In terms of powering them, I have wired a 4-way switch panel into the 12v supply via the leisure battery. This should let me independently switch on/off each of the 1m light strips.

Question - do I need to install x4 LED drivers between the switches and the LED light strips or can I go direct from the switch panel?

Cheers!

 

[roadtripper]

LED strip will need a constant current driver - the "12v" of a raw feed from the van electrics will in reality vary from right down to around 11v and can peak right up to around 15v with a smart alternator.

You might find a driver that will be happy being upstream of the switch so you only need one, but many are not happy being on with no load connected so check the specs for minimum load.

 

[Bigsidavies]

Mmm. I have a 7m run of cob led around the outside of the pop top. It’s got a switched and fused feed from the load output of the Victron mppt controller and is controlled using an app via this Bluetooth controller.

SP621E Music Bluetooth App Controller for WS2812B WS2811 | eBay

2, Support automatic device connection and automatic re-connection when the APP turns on. 6, Compatible with the common single-line LED driver IC on the market, can drive up to 600 pixels. 8, Built-in 18 music effects, effect length adjustable, sensitivity adjustable.

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It never crossed my mind to think about the voltage variation.
Anyone know if the mppt load output is a constant 12v?
Edit:-google suggests the load output isn’t a constant. I’ve had no issues so far, the Bluetooth controller states 5v-24v so I guess the only thing that might be unhappy is the actual light strip.
Is this going to be an issue?

 

[drinfinity]

Mine are direct to the leisure battery. No issues so far with them after 2 years.

They are switched via an electronic relay, so I can have more than one push button switch at various places in the van. That way the power current doesn’t have to go all the way round the van three times to minimise voltage drop. Instead the push switches momentarily earth the signal cable to the relay, which toggles the lights on and off.

Low Pulse Trigger Board Mini... https://www.amazon.co.uk/dp/B07NXY8V4K?ref=ppx_pop_mob_ap_share

 

[roadtripper]

With LEDs the issue really is current not voltage - but the wide voltage variation can cause current issues.

LED strip tends to have built in resistors for the nominal voltage, and at 12v it will tend to be arranged as 3 LEDs in series to minimise the loses and more closely match the voltage.

The issue is that current needs to be controlled as overdriving LEDs dramatically shortens their life, while the built in resistors will help without active control they will be overdriven as well as the voltage across the resistor will be much higher, so the power dissipated is higher. If it's built cheaply that may be more power than they are rated for, either way they will run hot wasting some of your electricity and shortening the life of the strip (heat can age the gel and adhesive)

In your case @Bigsidavies the Bluetooth controller will be managing the current. Most good controllers will work from 5v (USB) to 24v (architecture) as the 3 common voltages are 5/12/24 and they will have a voltage regulator for their own power. They don't control the voltage, it's expected that you supply them with the correct voltage for the strip, they just manage the current

It's the difference between it working and working well. Strip can be expensive and hard to replace well - the failures will tend to be short annoying sections as one of the resistor+3 LEDs sections fail.

If you have a controller that's dimming it will be doing PWM to effectively control the current and you should be OK, personally I wouldn't direct attach strip to something that is exposed to smart alternator voltages. If you do then making sure the strip is mounted on metal to help conduct the heat will help.

 

[Bigsidavies]

Thanks @roadtripper. My leds are on the metal external frame of the pop top so only in use when the roof is up. Put them on for Busfest really.
The controller does dim so I guess that will help.
I was more worried about it spontaneously combusting rather than shortening the lifespan. Probably only get used about 5 times per year.

 

[drinfinity]

@roadtripper Thanks for the details. I’m probably getting away with it through good luck rather than good judgement then. My LEDs are not on when driving, and don’t get many hours use. I’ll look for an appropriate driver.