12v led light strip connected to 12v battery turned off after 20 min

[johannes23]

Hi!

I am not sure if this is the correct place to post this question, please let me know if I should repost somewhere else

Today I tried hooking up a 12v light strip (2 meters long), to a service battery in my campervan. It worked fine for about 20 minutes, but then it suddenly turned off. I have wired the light strip through a 5 amp fuse from the battery, then through a switch. Do you know what the problem might be? Do I need a power supply even when my battery is rated at the same voltage as my light strip?

Greatly appreciate all answers!

-Johannes

 

[Lynx_Arc]

Either it has a regulating circuit or you may have been running the motor on the van and the voltage was too high as voltage in vehicle charging systems or some SLAs have higher voltage than 12V..... up to 14.5v which could be too much. I would wait an hour and see if it works again or not.

 

[HarryN]

An LED fundamentally needs to be driven by a constant current driver.

Most LED strip lights attempt to simplify the driver down to 3 or 4 LEDs in series with a small resistor - repeated over the length. If the voltage is very constant, then the current flow will also be fairly constant. I built a number of hobby flashlights using this method.

Some are also sold without the resistor on board and rely on the customer to add a constant current driver.

Normally these types of LED strip light setups with resistors are also sold with a 120 vac - nominal 12 volt / constant voltage power supply, but you skipped that part.

Often the places that sell these strip lights also sell a "driver / dimmer / color changer " that you can put in the circuit.

Did you do anything to mount the LED strip inside of a track for heat management or mount them right to wood?

HarryN

 

[SLLHUT]

We suggest that the amp of your lithium battery is 2-3 times the total power of the lamp, if the 2 meters long led strips is only 12A 3A, then a 9-10A lithium battery is a better partner,
Another point, please make sure the output power of the battery is between 11.5-12.5V DC
Hope this works for you,

 

[Dave_H]

I think we need to know more details of the LED strip; such as is it white or RGB? Some vendor specs could help. Often the total power, or power per unit length, may be given.

Your 12v strip should work well either with suitable PSU (voltage, current rating) or from battery of suitable capacity.

Does strip get overly warm or hot? When it turns off, will it come back on right away? Does brightness change before shutting off?

Looking closely at the strip, can you report any design detail such as resistors or driver chips (or post an image)?

Can you measure operating voltage at input, and current? Hard to imagine strip that length drawing close to 5A at 12v, but 5A fuse would be OK.

What is your service battery rating, and how well charged is it, when this happens?

Dave

 

[HarryN]

We suggest that the amp of your lithium battery is 2-3 times the total power of the lamp, if the 2 meters long led strips is only 12A 3A, then a 9-10A lithium battery is a better partner,
Another point, please make sure the output power of the battery is between 11.5-12.5V DC
Hope this works for you,

The voltage of an AGM battery goes considerably higher than this, especially during normal charging.

When it is cold outside, then the voltage to charge is even higher.

For LiFe batteries, they run about 0.5 - 1.0 volt higher than what you list, in addition to the higher voltage during charging.

It sounds like the right way to use your LED strip is to use a constant current driver or constant voltage driver?

Not picking on you - appreciate your efforts. The exhaust fans in RVs and vans have exactly the same problem - they are not really rated for the real voltage range experienced.

 

[alpg88]

Those strips already have resistors in them so they do not need any extra drivers, just a 12v line. those strips are ok with lower voltage, if the voltage is too high, they overheat fast. if the strip is not a silicone molded one, leds and resistors may unsolder themselves, and fall off, same can happen to wires soldered to the strip itself, did you inspect your connections? how about the strip itself? any traces of overheat? since it went out completely, and did not dim, or lost few clusters, i'm thinking the wires might come off from the strip.
I would install dc-dc regulator, (cost 3-5 bucks on ebay, lm 2596 based) and run the strip at 10V not 12, you will not see much of a loss as far as the output, but you'll stretch the life of the strip considerably, i'd say you'll even save it, even driven at 12 v those strips lose brightness due to heat, but running it at lower voltage drops the heat, while suffering minimal loss of the output, i've used many different strips for various projects, so i definitely know how to burn one, and how to make one work a long time.
I used to believe if you glue that strip on an aluminum channel, it will dissipate the heat and all be peachy, but in reality it did not matter at all, whether they were glued on a aluminum angle or on a piece of wood the result was basically the same, they all dimmed, some sooner some later. after a year they had about 1/3 of previous output, but 10V strips ran 24/7 none stop for years with no decline in brightness, thou sometimes clusters (3 leds) on some strips would go out, but that was due to defective led in that clusters. ( some of those strips are made better than others).

 

[Dave_H]

I would install dc-dc regulator, (cost 3-5 bucks on ebay, lm 2596 based) and run the strip at 10V not 12, you will not see much of a loss as far as the output, but you'll stretch the life of the strip considerably, i'd say you'll even save it, even driven at 12 v those strips lose brightness due to heat, but running it at lower voltage drops the heat, while suffering minimal loss of the output, i've used many different strips for various projects, so i definitely know how to burn one, and how to make one work a long time.

A good suggestion, running the strip at lower voltage (say even 11v) and agree it should extend the lifetime. It will stabilize operation over voltage variations. I recommend OP check that brightness and operation are OK at 10v. If strip is white LEDs with 3 series (common), 10v is around the dropout region, based on my tests with variable supply on 12v automotive lighting using 3S connection for buck driver.

Still looking for OP answers to my recent questions, which should help clarify.

Dave

 

[alpg88]

They can go lower than 10, i use 6xaaa or a 9 volt for dog harnesses, I build around a dozen by now. even at 9v they are still bright, and shut off completely when AAA cells have a volt or less in them with no load.
they way a see that cells are halfway gone is blue no longer lights up, even thou red and green still going strong,

 

[Dave_H]

They can go lower than 10, i use 6xaaa or a 9 volt for dog harnesses, I build around a dozen by now. even at 9v they are still bright, and shut off completely when AAA cells have a volt or less in them with no load.
they way a see that cells are halfway gone is blue no longer lights up, even thou red and green still going strong,

I also do this with some short amber LED strips designed to run from 12v. They are very (uncomfortably) bright on 12-14v but run from 9v battery typically starting in 7-8v range (typical when removed from smoke alarms), it is very pleasant nightlight at lower brigtness. When batteries run down below 6v (3 series of amber) they go to other devices to run them down further.


Dave