LEDs in series

[yawood]

This is a question for Sergio (or other equally qualified person):

I have multiple 12V LEDs and I want to run them from the 48V pack voltage (rather than from my 12V reducer). Theoretically I should be able to connect four of them in series and drive them from the 48V. Is that sufficient or do I need to add a Constant Current driver to ensure there is no thermal runaway? I know thermal runaway can be a problem if you have two or more strings in parallel but does it still apply to only one string?

If the driver is necessary, would this be an adequate (probably overkill) solution?

[Mooncarter]

I'm not qualified to comment on this but it is an interesting topic.

Following.

[BigMikey]

For that to work all of your 12v lights would need to be on at the same time. I’m less concerned about thermal runaway than overall functionality. Also those little pcb board devices have a poor record surviving the shock of golf cart riding.

This is what I have.
Cllena DC 36V 48V Step Down to 12V 30A 360W Voltage Reducer Converter, Waterproof DC/DC Buck Transformer Power Supply https://www.amazon.com/dp/B07L7M82WF..._Yav2CbZFCG4CY

Then you just parallel off all your 12v circuits. Then you can use a switch or switch and relay to turn on / off your lights.


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[teecro]

As far as I know that ain't gonna work. You can run incandescent lights in series as they work on resistance but LED lights need to receive voltage within a specific range for their electronic circuits to work properly.

[yawood]

Originally Posted by BigMikey

For that to work all of your 12v lights would need to be on at the same time. I’m less concerned about thermal runaway than overall functionality. Also those little pcb board devices have a poor record surviving the shock of golf cart riding.

This is what I have.
Cllena DC 36V 48V Step Down to 12V 30A 360W Voltage Reducer Converter, Waterproof DC/DC Buck Transformer Power Supply https://www.amazon.com/dp/B07L7M82WF..._Yav2CbZFCG4CY

Then you just parallel off all your 12v circuits. Then you can use a switch or switch and relay to turn on / off your lights.


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I've already got a voltage reducer but I want to run the LEDs off 48V (easier wiring in this case ) and I want the LEDs to be all on at once. I already have the 12V LEDs and I'm just looking at ways of making it work. They are to be reversing lights and will be wired in via a relay as per Sergio's instructions in MoonCarter's
http://www.buggiesgonewild.com/desig...y-body-ds.html

[rib33024]

What LED's are you using? Most led's run on a range of volts. Like 5v to 60volts they are not just for 12 volts

[Sergio]

The type of LEDs will make a difference, if they are plain panel mount LED with a resistor for a 12v operation, then 5 in series would work.

If they a a cluster of LEDs with a driver, then it would not work.

Since you are using a 48v coil relay powered by the FNR or reverse buzzer, the relay contacts will work fine with 12v or 48v for the LEDs.

[yawood]

Originally Posted by Sergio

The type of LEDs will make a difference, if they are plain panel mount LED with a resistor for a 12v operation, then 5 in series would work.

If they a a cluster of LEDs with a driver, then it would not work.

Since you are using a 48v coil relay powered by the FNR or reverse buzzer, the relay contacts will work fine with 12v or 48v for the LEDs.

Thanks Sergio, they are the former. Why 5 rather than 4?

[Sergio]

Since the LEDS would be exposed to the full charging voltage, 5 in series would be safer.

A lot of times the LEDs in those panel mount are driven close to maximum in order to get more light out of them so a little buffer in the maximum voltage per LED would allow for a cooler/long term operation.

Since the relay will isolate the 48v from the 12v side, why don't You want to just put them in parallel and not have to worry about how many?

[pattyandrick]

Just hook them temporary and see what happens. I tried it and it didnt work one light was dim. Add another reducer

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