LED burn out, why didn’t a fuse blow?

[Jimbob45]

morning all

We were sitting outside our van last night, enjoying the evening warmth in France with a cold beer. Switched on the awning light, few minutes later noticed smoke coming from the light and a strong smell of burning! Quickly turned it off and also disconnected the supply from the inside.

As you can see, the LED has burned out, but I don’t get why a fuse didn’t blow?

I’ve never had an LED fail like this before, and it’s got me worried about the electrics on the van. Any thoughts on what caused this?

 

[pappajohn]

Cheap Chinese fuses have some strange behaviour.

Cheap chinese fitting.

 

[tonyidle]

If the LED didn't go short circuit the fuse wouldn't fail. And it may be a higher value fuse than necessary.

 

[NR]

Because the LED current rating is less than the fuse.

 

[meanders]

Even if the one LED went short circuit there are 9 others in the string, so any fuse would be rated for the 9 not a single.

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[Jimbob45]

Even if the one LED went short circuit there are 9 others in the string, so any fuse would be rated for the 9 not a single.

Ok thanks. Explains the fuse then.
Could have been a fire risk it’s mounted on a wooden block. Lucky we spotted it!
Now need to find a replacement…!

 

[Richard n Ann]

Was your charger on? Sometimes the LEDs run a bit hotter on 14v and have a shorter life

 

[steve69]

Warning!.... trip switches can be faulty too. a couple of years ago one of my trips failed to trip as the wires and insulation leading into it started melting. Luckily I was in at the time and could smell it.

 

[meanders]

It looks like one of these.

 

[Jimbob45]

Was your charger on? Sometimes the LEDs run a bit hotter on 14v and have a shorter life

Yes plugged in the mains for the aircon!

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[Gromett]

Was your charger on? Sometimes the LEDs run a bit hotter on 14v and have a shorter life

This is something a lot of people don't realise.

Unless the LED product specifically states a voltage range it is likely to be cheap unregulated and you should provide your own 12v regulated supply.

It also extends the lifespan.

 

[Jimbob45]

It looks like one of these.

Spot on, thanks!

 

[Jimbob45]

This is something a lot of people don't realise.

Unless the LED product specifically states a voltage range it is likely to be cheap unregulated and you should provide your own 12v regulated supply.

It also extends the lifespan.

As far as I am aware it would have been the original Burstner fit, so I hope they would have ensured it would be ok at 14v!

 

[Gromett]

It looks like one of these.

Well that looks like it is not regulated but they are charging the price of a regulated device.

If it is this one, I would add a 12v regulator to the supply.

I use something similar to this; Not this one specifically as I bought mine years ago and it is no longer available. But any 12v to 12v regulator with an input range over 8-15V should be fine.
I prefer the metal cased ones for reliability.

 

[tonyidle]

This is something a lot of people don't realise.

Unless the LED product specifically states a voltage range it is likely to be cheap unregulated and you should provide your own 12v regulated supply.

It also extends the lifespan.

I've used a number of domestic 12v LED down lights. The ones in regular use have lost several of their chips due, I assume, to overvoltage. I'm in the process of installing a dc-dc regulator in the common lighting supply.

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[Gromett]

As far as I am aware it would have been the original Burstner fit, so I hope they would have ensured it would be ok at 14v!

When you take the old one out. can you rip it to pieces and take some pictures. Do the wires go straight to the LEDs or is there a power regulation circuit prior.

sorry, just very curious now

 

[Gromett]

I've used a number of domestic 12v LED down lights. The ones in regular use have lost several of their chips due, I assume, to overvoltage. I'm in the process of installing a dc-dc regulator in the common lighting supply.

I learned this less about 10+ years ago. As a fulltimer I was going through LED bullbs at a stupid rate of knots

 

[Jimbob45]

When you take the old one out. can you rip it to pieces and take some pictures. Do the wires go straight to the LEDs or is there a power regulation circuit prior.

sorry, just very curious now

Will do! It’ll be a couple of weeks as away on hols in France.

 

[Gromett]

Will do! It’ll be a couple of weeks as away on hols in France.

Really appreciate it. My curiosity knows no bounds

 

[Richard n Ann]

I've put 2 six amp silicon diodes in series with my kitchen LED strips. They drop the voltage by about 1.2v and the LEDs are now running a lot cooler.

They'll also drop the battery voltage by 1.2v when not on ehu, you probably won't notice... And the current draw will be much less win win

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[tonyidle]

I learned this less about 10+ years ago. As a fulltimer I was going through LED bullbs at a stupid rate of knots

Yep - pretty well as soon as I started using LEDs too. But laziness and low cost meant it has taken until now to do something about it.

 

[Jimbob45]

Voltage on the control panel, although not sure this is going to the lights as haven’t got my multi meter with me

 

[Jimbob45]

When you take the old one out. can you rip it to pieces and take some pictures. Do the wires go straight to the LEDs or is there a power regulation circuit prior.

sorry, just very curious now

a bit of a delay, but took the old one out today, doesn’t look good and wires are directly wired to the LED’s.. just says 12v on the back ..

 

[Jimbob45]

replaced it with a Labcraft Astro, which is rated at 12-14v and UK made (if that’s a good thing these days!)
looks better and is quite bright.

 

[Gromett]

a bit of a delay, but took the old one out today, doesn’t look good and wires are directly wired to the LED’s.. just says 12v on the back ..
View attachment 806972View attachment 806974View attachment 806975

That looks like an el cheapo. No current regulation so when on 14.6v charging they do have a tendency to get very hot and fail early.

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[Badknee]

This is something a lot of people don't realise.

Unless the LED product specifically states a voltage range it is likely to be cheap unregulated and you should provide your own 12v regulated supply.

It also extends the lifespan.

I always buy my “12v” led lighting from Aten lighting in Melton Mowbray as they are rated at 8-30 volt and never had one fail.

Dimmable too…….

 

[Cush]

Is this more likely to happen if I have upgraded my system to lithium as the max charge voltage will be way higher than my old sargent’s 13.5 v?

 

[Jimbob45]

That looks like an el cheapo. No current regulation so when on 14.6v charging they do have a tendency to get very hot and fail early.

nothing to it really, just a strip of leds, I think it’s the factory fitted one, so you would have thought they would have put a decent one on!

 

[Gromett]

as they are rated at 8-30 volt and never had one fail.

That is regulated. Takes 8-30 volts and regulates it so that the current is consistent and within spec of the LEDS. No overheating or early failures. That is what people should look for

 

[Gromett]

Is this more likely to happen if I have upgraded my system to lithium as the max charge voltage will be way higher than my old sargent’s 13.5 v?

Are you sure. 13.5V seems a bit low even for lead acid?

But yes. You really should use either regulated LEDS or install a regulator for the lighting circuit in my opinion.

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