And another H1/H7 Halogen-Driver KIT !?

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General features:

* Soft start bulbs
* Up to 1000 lumens of extra light from standard bulbs
* Permanent PWM operation with PLL regulation
* Overvoltage and spikes protection (17 volt cut-off)
* Optional undervoltage protection against deep discharge of the battery (10.5 volt cut-off)
* Voltage limitation to 14.5 volts measured at the lamp base
* Variable supply voltage up to 16.0 volts
* For standard H1 and H7 bulbs (separate supply connections)
* Driver is Plug-n-Drive
* Powered by a AVR® Attiny13/45 Microcontroller
* Size (112mm x 62mm x 31mm)

Most of the kits on the market consist of a relay and thick cables to get the full battery voltage to the halogen lamp, and yes, the lamps usually burn brighter. Mission accomplished !?

Not quite, ..... most lamps die an early death because the inrush current is extremely high due to the thick cables and the lamps then burn out prematurely because the lamps are already weakened by the higher operating voltage.

Another problem is that despite the direct connection to the battery, the desired 14 volts are not normally present on the lamp. The cause are line losses or resistance losses. With a relay kit you can usually bring about 13.2 volts to the lamp sockets, since these kits cannot do without losses either.

Sounds like it's better to leave everything as it is. After all, there are all of these 100% + halogen lamps or LEDs. However, anyone who has tested such super lamps comes to the conclusion relatively quickly that the + 160% higher brightness is more like + 6%. I tested some of these lamps but they didn't get the result I wanted, they were barely brighter. Then I also tested some LEDs, they are a bit brighter, but rather uncomfortable due to the 6000K color temperature.

So the question was, where can a bright 3500-4000K halogen light come from?

The only way is to take a standard lamp and increase the operating voltage significantly!

Increasing the voltage with a relay kit to 13.2 volts brings already a visibly better result. Unfortunately, that was still not what I imagined under bright light. So, I took my laboratory power supply, voltage further up to 14, 14,5 ,15 volts. At 15 volts, the halogen light is as I wanted it to be, white and super bright, but still unmistakably halogen light and not as cloudy soup as from an LED, just crystal clear light.

The disadvantage was that the bulbs life was, let's say, suboptimal. The 15 Volt alone was enough to wear out the lamp after a very short time, and what the high voltage couldn't do, the inrush current did.

So, something like an Halogen-driver had to be produced!

The Halogen-driver had to do two things; limit the inrush current on the one hand and the operating voltage on the other. For this reason I built a Halogen-driver that limits the current when the lamp is switched on in order to bring the lamp up to temperature. After a preheating time of 1s, the voltage is increased to operating level by an increasing PWM signal.

The operating voltage for the lamp is set to a maximum of 14.5 volts. The halogen driver has a sensor line to measure the actual operating voltage directly at the lamp base. In this way, all external factors such as cable lengths, contact points etc. that cause voltage drops are compensated. This is especially important if the lamp gets its operating voltage from a 12 to 16 volt step-up converter. As long as the operating voltage comes from the alternator or the battery, the lamp voltage is normally below 14.5 volts and does not need to be limited. The halogen driver is then only in operation as a soft start module and as an over and under voltage monitor.

The Halogen-driver has a separate input for the supply voltage of the lamps. This cable needs to be connected directly (without a relay) to the battery with a 25A fuse. The Halogen-driver itself is operated with the voltage of the original low beam, which comes from the light switch.

The best result in terms of brightness is achieved with an output voltage of 16 volts, which definitely leads to 14.5 volts at the lamp base. With a 16 volt step-up converter you still have some reserve in terms of cable lengths. If you don't want to overdo it and use a 12 to 15 volt step-up converter, 14.0-14.3 volts are applied to the lamp base, which already leads to a considerably higher light output.

The power at 14.5 volts is approx. 74 watts x2, plus 10 watts control losses. A step-up converter would therefore have to deliver at least 160 watts at 16 volts to adequately supply the lamps. A small reserve in the converter could not hurt ....

An H1 lamp has a light output of around 1550 lumens at 12 volts, that is 28 lumens / watt. This means that at 14.5 volts and measured 74 watts, a light output of approx. 2075 lumens is achieved. With 2 lamps that is 1000 lumens more light output. The light color changes significantly to 3500 K or higher.

Tests have shown that a standard lamp will last more than 1000 switching cycles and more than 150 hours of operation when a 16 volt step-up converter is used. The service life depends on the brand of the lamp and the supply voltage. If the battery supplies the lamps without a converter, the service life is certainly the standard value. A good compromise between brightness and service life can be achieved with a 15 volt step-up converter.

The final tests are finished, the software for the controller is ready. I'm currently waiting for the first professionally manufactured circuit board to be able to show something here. If there is enough interest, it is no problem to produce larger quantities. I have to calculate the costs when the final piece is finished.

Stay tuned, and if You are interested in a Halogen-Booster, please email me ....

{Side update}

January 2021


Connection plan


Landypedia Lamps
Spannungsabfall bei Kabeln
Test H7 Gluehlampen
15V step-up Converter
16V step-up Converter