Eberspacher start up cause LEDs to flicker

[Skyliner33]

Have had a search but couldn't find the answer to my problem.

I have just had 2 single colour LED strip COB lights fitted. I noticed last night that when I start up the Eberspacher heater the lights flicker for a few minutes whilst the heater is starting up. Then after a few minutes as the heater is up to temperature and settling down the flickering gets less and then stops.

The LEDs have been wired up so that they work in the same was as the OEM courtesy lights and have a separate on/off/dimmer switch.
As far as setup goes I have a Renogy LiFePo4 100Ah battery with 16mm2 cable to a Blue Sea Systems fuse box. The 2 power leads to the heater are fused in this. Also there are 2 power leads for the lights (5A fuses) and 2 power leads (3A) that I believe are for the controller. There are also 2 negative leads from these connected to the neg bus bar of the fusebox.

It seems to me that somehow the heater is interfering with the lights. Would a solution be to get a new fuse box specifically for the Eberspacher and run new cables from the battery to that fuse box, or would there somehow still be interference somewhere, maybe in the negative lines?

Thanks for any input.

 

[oldiebut goodie]

What you are seeing is voltage drop due to the glow pin being energized - you can draw around 10 - 12 amps at this point. Usually caused by underrated cabling or failure to wire the heater direct to the battery.

 

[Skyliner33]

What you are seeing is voltage drop due to the glow pin being energized - you can draw around 10 - 12 amps at this point. Usually caused by underrated cabling or failure to wire the heater direct to the battery.

Thanks. I thought it must be something like that.

As for cabling it is 16mm2 from battery to fusebox and then from fuse block onwards its the supplied Eberspacher loom, so I would be surprised if its caused by underrated cabling.

If I get the multimeter out what voltages do you suggest I measure to check for drop? Thanks

 

[oldiebut goodie]

Assuming that the battery is fully charged and healthy:
I would check the voltages at every available point you can access, battery, inlet side of fuse box, outlet side of fuse box for lights and heater to try to pin down where it is happening. Check that the heater and battery ground connections are clean and tight - this is often overlooked and can cause high current draw if dodgy and consequent voltage drop.
It may be something that you cannot cure due to the leds being ultra sensitive to voltage drop due to inadequate driver.

 

[Skyliner33]

Assuming that the battery is fully charged and healthy:
I would check the voltages at every available point you can access, battery, inlet side of fuse box, outlet side of fuse box for lights and heater to try to pin down where it is happening. Check that the heater and battery ground connections are clean and tight - this is often overlooked and can cause high current draw if dodgy and consequent voltage drop.
It may be something that you cannot cure due to the leds being ultra sensitive to voltage drop due to inadequate driver.

The battery was about 80% charged, but LiFePo4 so shouldn't suffer voltage drop, but I will fully charge today and test again later.

I will do a bit of measuring and report back later. Thanks again

 

[Skyliner33]

@oldiebut goodie
Took these measurements.

LED lights off
Heater Off

P.d. across leisure battery: 13.04V
Pd. Fusebox in-Battery -ve: 13.04V
P.d. out of fusebox - at connection to these wires:
P.d. Eberspacher 20A circuit: 13.04V
P.d. Eberspacher 5A circuit: 13.04V

P.d. Lights 1 +ve (5A): 13.04V
P.d. Lights 2 +ve (5A): 13.04V

P.d. Lights controller 1 +ve (3A): 13.04V
P.d. Lights controller 2 +ve (3A): 13.04V


LED lights ON
Heater Off

P.d. across leisure battery: 13.04V
Pd. Fusebox in-Battery -ve: 13.04V

P.d. out of fusebox - at connection to these wires:
P.d. Eberspacher 20A circuit: 13.01V
P.d. Eberspacher 5A circuit: 13.01V

P.d. Lights 1 +ve (5A): 13.01V
P.d. Lights 2 +ve (5A): 13.01V

P.d. Lights controller 1 +ve (3A): 13.01V
P.d. Lights controller 2 +ve (3A): 13.01V

I will next take the same measurements with:

LED lights ON
Heater ON

Values to come later

 

[Skyliner33]

Right I took some more measurements today

Battery voltage 13.21V lights on
Voltage after LED fuse 13.20V lights on.
Heater switched on - battery voltage 13.12V
voltage supply to LEDs (after fuses) 13.11V

So I am thinking it cant be voltage drop that is causing the lights to flicker.

So would a voltage stabiliser like this help, would I need one that outputs 13.8V or 12V?

 

[oldiebut goodie]

It seems odd to me, the draw from the glow pin is constant not pulsing ( gradually diminishing from around 10A down to 8A ) so if it isn't voltage drop before the led driver circuit it must be the led driver that is being affected somehow. Any pulse from the motor operation would be constant during heater operation so that can be ruled out.
I would look at the voltage being put out by the driver - this is where an analogue test meter is better than a digital multimeter - moving coil meters will show the voltage fluctuations not seen on a multimeter.

 

[PaulR83]

Right I took some more measurements today

Battery voltage 13.21V lights on
Voltage after LED fuse 13.20V lights on.
Heater switched on - battery voltage 13.12V
voltage supply to LEDs (after fuses) 13.11V

So I am thinking it cant be voltage drop that is causing the lights to flicker.

So would a voltage stabiliser like this help, would I need one that outputs 13.8V or 12V?

View attachment 257364

I had this exact same issue with my interior lights when running the diesel heater on my leisure battery.
I fitted the above 12v output version to the lighting circuit and all issues have gone away. I do isolate it when lights aren't in use. On occasion I haven't and I'm sure it's adds a slight load to the battery.
Strange how only us seem to have had this problem and no one else.

 

[oldiebut goodie]

Which heater - was it an Eberspacher as well? Just wondering if there is something common to them.

 

[Skyliner33]

I had this exact same issue with my interior lights when running the diesel heater on my leisure battery.
I fitted the above 12v output version to the lighting circuit and all issues have gone away. I do isolate it when lights aren't in use. On occasion I haven't and I'm sure it's adds a slight load to the battery.
Strange how only us seem to have had this problem and no one else.

Thanks @PaulR83 I have 2 LED strips running on separate 5A fuses. DO you think 1 of these and then splitting the output to the 2 strips would work, or would I need 2 of the units.
Yes, strange how it us just us out of all the forum members, but I think its more common than we think.

 

[Skyliner33]

Which heater - was it an Eberspacher as well? Just wondering if there is something common to them.

I just found this on the Sprinter forums:

Webasto EVO 40 LED Lights Flickering Solved

Short story: Flickering LED lights as your Webasto heater starts up and shutsdown? Try a DC-DC converter in the light circuit, before the lights. Solved the issue for me. Long Story: In case this post helps someone else... I installed a Webasto EVO 40 diesel heater in my 170 WB extended...

sprinter-source.com

 

[oldiebut goodie]

That makes sense - that is where I suggested next, the led drivers being at fault.

 

[PaulR83]

Thanks @PaulR83 I have 2 LED strips running on separate 5A fuses. DO you think 1 of these and then splitting the output to the 2 strips would work, or would I need 2 of the units.
Yes, strange how it us just us out of all the forum members, but I think its more common than we think.

Interesting for sure. It was very subtle I recall but just annoying. Can't remember if it did it on hook up too.
Depending on load you may just want to common them up. I doubt the lights draw that much. Mine were all run on tiny cables which may not help.
I only did it for my main roof lights, I added it before my touch dimmer and all works. I didn't do it for my tailgate lights and they still do it, but rarely use them and if I did, I doubt the heater would be on.
I find it strange too the only 12v regulator is a Chinese ebay one.
Think the only other I found was Victron one too if you want to go full team blue! They are slight bigger and I don't think it would have fitted behind my B pillar trim.

 

[Skyliner33]

That makes sense - that is where I suggested next, the led drivers being at fault.

Thats got me thinking if its better to change the LED drivers (if they have them) or to get one of those buck boost things.

 

[Skyliner33]

Interesting for sure. It was very subtle I recall but just annoying. Can't remember if it did it on hook up too.
Depending on load you may just want to common them up. I doubt the lights draw that much. Mine were all run on tiny cables which may not help.
I only did it for my main roof lights, I added it before my touch dimmer and all works. I didn't do it for my tailgate lights and they still do it, but rarely use them and if I did, I doubt the heater would be on.
I find it strange too the only 12v regulator is a Chinese ebay one.
Think the only other I found was Victron one too if you want to go full team blue! They are slight bigger and I don't think it would have fitted behind my B pillar trim.

I'm in the process of fitting a cheap strip of RGBWW LEDS with a cheap controller. I have 2 of these in the tailgate I didnt think about testing these yet.

 

[PaulR83]

Worth a try.
Could just be the controllers are extra sensitive to electrical noise.
My lights were all installed by someone else, so can't easily try others.

 

[Skyliner33]

Worth a try.
Could just be the controllers are extra sensitive to electrical noise.
My lights were all installed by someone else, so can't easily try others.

Out of interest, who installed them? Pm me if you prefer.