Hey guys,
I'm upgrading my car lights with a custom light rig. The problem is that the car battery load kills my led anytime I connect them.
Can you please suggest me a suitable resistor to pair with these cute lights, so they don't die immediately after I turn on the engine?
https://www.aliexpress.com/item/400....order_list.order_list_main.22.27be1802sQt9Zm

Power:3.84W
Input VoltageC12v
Color Temperature:6000K-8000K
Vehicle Application:Universal
Net weight:14g
Size:17.4cmx 1.5cmx0.5cm (L x W x H)
Life: 50,000 hours

Thank you so much for your attention and participation.

 

So they are OK, until you start the motor?
If so, it sounds liker the 14.5v that is generated on motor running they may not like?

 

They are working ok with this battery. But they burn when connected to the car battery. I guess it's some load problem. They can't handle the high Amps load.

 

What is "this battery"? What voltage is it outputting? I can't read the label on it in the picture.

Do you have a multimeter so that you can measure actual voltage and current?

 

It is illegal to modify external car lighting. Wrong color, wrong brightness and wrong angle.
Some people turn off all lighting (drive-in theater mode) then drive around in the dark with no lights or with parking lights.
They turn on the high beams in the daytime.

 

What is "this battery"? What voltage is it outputting? I can't read the label on it in the picture.

Do you have a multimeter so that you can measure actual voltage and current?

 

It is illegal to modify external car lighting. Wrong color, wrong brightness and wrong angle.
Some people turn off all lighting (drive-in theater mode) then drive around in the dark with no lights or with parking lights.
They turn on the high beams in the daytime.

I'm installing fog lights which are legal in my country. I've seen pretty crazy stuff riding around on the streets, so, I guess I'll look quite OKAY among them.

 

Another picture is not much help. We need the actual voltage while it’s not connected to anything. Then, the voltage under load and the current drawn by the load (LED lights)

 

Another picture is not much help. We need the actual voltage while it’s not connected to anything. Then, the voltage under load snd the current drawn by the load (LED lights)

Sure. Let me measure it.

 

So if that battery is delivering 11.1 V, that won't tell you much about what happens when it is connected to a battery and electrical system that normally operates in the 14 V to 15 V range.

These should be drawing a small enough current that you can put a pretty simple voltage regulator circuit to keep them happy. It might even be sufficient to put a couple of diodes in series with each one to drop the excess voltage.

 

LED light from AliExpress? 12VDC lighting for any make of car (in China?).
My American car has an alternator producing 14.5V.
The Lithium battery shown is for an RC toy car and is marked 11.1V which does not burn out the 12V LEDs.

 

So if that battery is delivering 11.1 V, that won't tell you much about what happens when it is connected to a battery and electrical system that normally operates in the 14 V to 15 V range.

These should be drawing a small enough current that you can put a pretty simple voltage regulator circuit to keep them happy. It might even be sufficient to put a couple of diodes in series with each one to drop the excess voltage.

Will this help?
https://www.aliexpress.com/item/100...2255956&spm=a2g0o.ppclist.product.mainProduct

 

Will this help?
https://www.aliexpress.com/item/1005004509441138.html?pdp_npi=2@dis!CAD!C$ 0.50!C$ 0.50!!!!!@210312ea16722559566665903e2735!12000029414102959!btf&_t=pvid:7a86c0a9-80fc-4b40-b27d-97de6b2bda2b&afTraceInfo=1005004509441138__pc__pcBridgePPC__xxxxxx__1672255956&spm=a2g0o.ppclist.product.mainProduct

Depends. We need much more information about the LED lights first, before the battery information is useful.

You’ve been asked several times. What current does the lights draw in operation? Using the battery that works, how much current is drawn?

 

Will this help?
https://www.aliexpress.com/item/1005004509441138.html?pdp_npi=2@dis!CAD!C$ 0.50!C$ 0.50!!!!!@210312ea16722559566665903e2735!12000029414102959!btf&_t=pvid:7a86c0a9-80fc-4b40-b27d-97de6b2bda2b&afTraceInfo=1005004509441138__pc__pcBridgePPC__xxxxxx__1672255956&spm=a2g0o.ppclist.product.mainProduct

That depends. The LM317 has a recommended dropout voltage of at least 3 V, so it's not going to do much actual regulating if you are trying to get 12 V to the LEDs. With the engine not running, your voltage to the LEDs may be down so much that they can't illuminate well, or at all.

It also depends on what the total current is that you need to supply to all of your LEDs and whether that is within it's capabilities.

Finally, that circuit looks absolutely bare bones, which means it may not be able to survive long in the very harsh electrical environment of most cars.

I'd be more tempted to do with the series diodes approach and see if that works.

 

Depends. We need much more information about the LED lights first, before the battery information is useful.

You’ve been asked several times. What current does the lights draw in operation? Using the battery that works, how much current is drawn?

The AliExpress page indicates a nominal draw of 300 mA.

I'm a bit skeptical that these can provide very effective fog lights. But who knows?

 

They are working ok with this battery. But they burn when connected to the car battery. I guess it's some load problem. They can't handle the high Amps load.

The load is the same regardless of the type of battery, as long as the Voltage is the same.
So they fail even before the auto is started?

 

The load is the same regardless of the type of battery, as long as the Voltage is the same.
So they fail even before the auto is started?

I haven't tried to keep them working long with the turned-off engine.
I can conduct some experiments and post the results here.

 

That depends. The LM317 has a recommended dropout voltage of at least 3 V, so it's not going to do much actual regulating if you are trying to get 12 V to the LEDs. With the engine not running, your voltage to the LEDs may be down so much that they can't illuminate well, or at all.

It also depends on what the total current is that you need to supply to all of your LEDs and whether that is within it's capabilities.

Finally, that circuit looks absolutely bare bones, which means it may not be able to survive long in the very harsh electrical environment of most cars.

I'd be more tempted to do with the series diodes approach and see if that works.

I would get a premade Linear Regulator Module and stop right there.
I'm more of a visual nerd rather than an electrical one.
While I'm getting to you all the data requested above, could you suggest something premade that might just work fine for a couple of years or so?

 

I would get a premade Linear Regulator Module and stop right there.
I'm more of a visual nerd rather than an electrical one.
While I'm getting to you all the data requested above, could you suggest something premade that might just work fine for a couple of years or so?

A couple of diodes in series with each LED strip. You already have to wire up the strips. It will be an easy matter to put a couple diodes in series with them and cover them up with heatshrink tubing.

 

One would assume ( - dangerous, I know - ) that at 12 volts and 290mA there should be a current limiting resistor built in at a value of 41.38Ω (calculated). At 14.5V, which is absolutely possible, at 290mA there should be a current limiting resistor built in at a value of 50Ω.

The picture in the ad doesn't clearly show any chance of a resistor anywhere in circuit. Since it is coming from Mainland China - who knows WHAT you got. I did see a lot of high review marks, but those can easily be faked too.

Here's the specs they give:


I have to say I don't think 660 lumens is going to be sufficient for fog lights. Also, the spec claims 2W whereas the main ad states:



I have to wonder if you're getting what you think you've gotten. Or not.

Did you say they're good until you start the engine? If so, and you have a test meter that can measure 300mW then hook them up through the meter with it set to measure amperage. If the amperage is more than what it's supposed to be then there should be some form of current limiting; i.e. resistor or CC Regulator. I've also seen "Resistance Wire". If that's the case and you are trimming the wire then you might be inadvertently dropping the resistance and over-currenting them.

To be sure there's a lot more diagnostics required before you can hook them up and expect a useful light out of them. However, again, I don't think 660 lumens is going to serve you well as fog lights. Will make for good anti-collision lighting in foggy situations, but even that isn't fool proof (the fool in the car who thinks he can go 60 MPH in heavy fog just because he can barely see the spotty lines.

And at 74¢ a piece, what do you expect?