9VDC to power a 12VDC MR16 LED BULB?

[bcroe]

Pulse width modulation works, esp when a linear decrease in voltage doesn't give the desired
result. I used it to vary the brightness of Nixie tubes long ago. Bruce Roe

[CrazyJerry]

That is indeed a different twist - since I assume the voltage in your case is a square wave with varying duty cycle and a high of 12V. Sounds like something ripe for bench testing.

Voltage is DC direct from the battery bank into the PWM dimmer then out to the MR16 12 volt light. Input voltage varies per battery bank SOC. When I was using lead the input could be as high as 14.5 volts and as low as 11.2 volts. With the new lithium pack the input voltage is more stable and I'm seeing 13.3-ish down to 12 volts. Input voltage variation is also influenced by line loss due to distance from the battery bank - hence the spread in the numbers.

Both the bulbs and the dimmers are fairly inexpensive versions. Dimmer control is rated at 8 amps and that is pushing it based on heat.

Dimmer closely matches this one:
ugriL.jpg

Bulbs with longest life in system (4yrs) resemble this one:
economical_LED_MR16_lamp_LED_lamp_ul.jpg

CrazyJerry

[Living Large]

A different twist on this:
I've run MR16 leds for years (most are around the 400 lumen rating). They are all on Pulse width dimmers and after the 12 volts passes through, the typical voltage the MR16's see is anywhere from 7.6 volts and up depending on dimmer setting.

The oldest MR16 is 4 years and is used several hours nightly.

~CrazyJerry

That is indeed a different twist - since I assume the voltage in your case is a square wave with varying duty cycle and a high of 12V. Sounds like something ripe for bench testing.

[CrazyJerry]

A different twist on this:
I've run MR16 leds for years (most are around the 400 lumen rating). They are all on Pulse width dimmers and after the 12 volts passes through, the typical voltage the MR16's see is anywhere from 7.6 volts and up depending on dimmer setting.

The oldest MR16 is 4 years and is used several hours nightly.

~CrazyJerry

[Living Large]

Stayed bright until 10 volts then started dimming.

Based on that alone, personally I would not plan to run one 9V long term, but each to their own. Who knows from batch to batch and manufacturer to manufacturer what will happen? You may find that a simple bulb replacement isn't so simple.

[jflorey2]

Just curious here and wish to ask around if anyone have tried running a 12VDC MR16 LED lamp using 9VDC?

I tried it with mine and it worked down to about 7 volts. Stayed bright until 10 volts then started dimming. At 7 volts it became unstable - flashing on and off and buzzing.

[inetdog]

There are a couple of possible scenarios for the LED driver/emitter combination.

If there is only one LED, then it is not likely to be intended for 12V direct. More like 2-3V.
So the driver will be a buck type DC to DC converter and it will draw more current from the source at 9V than it would at 12V as it tries to maintain the same current at the LED itself.
If there is a series stack of LED emitters then the driver may be a simple linear regulator which is dissipating some power as it regulates 10-14 volts down to, say 9V for the LED stack. In that case 9V applied might not produce any light at all, but the bulb would last forever.

[Living Large]

Hi,

Just curious here and wish to ask around if anyone have tried running a 12VDC MR16 LED lamp using 9VDC?

Does it light up & does using lower operating voltage helps in extending the bulb's life cycle?

Thanks.

I researched this for an hour, and I came up with only a few sources of information. I found minimum recommended voltages of 10.5V and 11V - but I'd hardly call what I found definitive or mention of what happens at lower voltages. I found only one reference to bulb life, that implied life decreases below 10.5V. Again, I was disappointed I could not find better information.

[PV_boy18]

Hi,

Just curious here and wish to ask around if anyone have tried running a 12VDC MR16 LED lamp using 9VDC?

Does it light up & does using lower operating voltage helps in extending the bulb's life cycle?

Thanks.