How Stable Is The Electric Supply On A T6

[trooutie]

Ok strange question I hear you say But
I used to make and sell led mountainbike lights and have lots of leds and driver boards

now 10 years ago the driver circuit boards I used were not recomended for auto use due to the power being dirty and unstable with surges and stuff. but I am wondering if with the use of lots of electronic stuff on the modern motor are the voltages now a lot smoother and stable .

I am hoping there are some electronic gurus on here who can advise .

I will be making a light and experimenting to see if one of my drivers will survive but any advise would be welcome .

 

[Jean-Louis Bourdon]

euro 6 are pretty weird by design.
at constant speed driving the alternator "rests" to save on fuel,
and when you brake, the braking regens peaks voltage to about 16v , so that why they don't charge the automotive battery above 75%

most automotive electronics have their own regulators that usually work 9.5 to 18.5v for 12v systems and create stable 12v, 5, 3.3, 1.8v rails

 

[Pete C]

Your best bet would be to stick a voltmeter on the 12v supply and measure what happens, particularly on overrun.

Pete

 

[Jean-Louis Bourdon]

from
Pro Batt Ultra Battery to Battery Chargers, Non Waterproof, (Drip Resistant IP21)
middle of the page PDF

(i am not affiliated with them)

Smart Alternator Voltage

• Jean-Louis Bourdon
• 6 Dec 2018

 

[mmi]

T6:
When engine running observed voltages from 12.3 up to (only) 15.0 Volts. Recorded tens of hours in different driving conditions at temperatures -5C…+25C. Pretty hard to tell what the "typical" voltage would be as it depends... but seems to dwell a lot at 13.8 Volts.

During engine braking (regenerative braking) the voltage rises to max.

Voltage rise and fall rate never exceeded 0.5 Volts/second under any circumstances - during engine braking (braking no different) or when battery management changes between different charging/discharging modes. Thus takes seconds before full “regen braking” kicks in.

The above measured at starter battery terminals. Integration time at the measurements has been 100ms so can’t tell if there are any real spikes but not really expecting those as a battery is very good damping “high-frequency” energy. Had just few glimpses using oscilloscope to see any ripples riding on the top of main voltage.

Early/cheap LED drivers seemed to struggle at low voltages as they tried to harvest energy from low voltage by increasing current they absorb thus turning soon/eventually into smoke. So if hooking something into dimming interior lights that case is probably worth to double check.

 

[Pauly]

Not sure engine bay voltages would be comparable to cabin voltages the other side of a voltage regulator (but not sure exactly what supplies come through the regulator and what don’t ?)

 

[scotia]

I used to make and sell led mountainbike lights and have lots of leds and driver boards

sorry slight hijack....but Troutie is back?! I always wanted one of your lights back in the day hope you're well and all is good? Singletrack misses your posts..

 

[trooutie]

sorry slight hijack....but Troutie is back?! I always wanted one of your lights back in the day hope you're well and all is good? Singletrack misses your posts..

Hi Scotia seems like a lifetime ago now ( Damn China for copying and cheapening everything ) but still dabble as you can see , I still lurk on STW but dont post much at the moment

 

[trooutie]

Thanks for the informative replies I just had a volt meter on the 12 volt ciggie lighter socket and the voltages did fluctuate from 12 to 14 volts as I revved the engine .
I had a reply from the guy who made the driver boards www.taskled.com and this is his reply

You could use the bflex in automotive, but I'd recommend you put a series inductor (few dozen uH) and then a capacitor across the input to the driver - electrolytic, say 10uF/35V or similar. The electrolytic cap is necessary to damp and spikes that get through the inductor.

cheers,
george.

I do have a couple of his automotive led drivers so will use those for my planned fog lights