Lighting from the main battery

[norkmeister]

Has anyone rigged up a headlight system that taps into the main 36v drive battery?  I am thinking of doing such a thing by use 3 12V LED downlights in series with some sort of current limiting resistor and was wondering what if anything anyone else has done.

The alternative if to use a DC-DC switch mode power supply that accepts the 36V input.

[ahend]

I have bought a couple DC-DC converters to power my head lamp and tail lamp system but have not wired them in yet. The plan is to mount them under my rear rack, somehow protecting them from moisture and dirt. My head lamp is 6 volt and my tail lamp is 3 volts. I could not find a single converter to service both systems. My pack has plenty of spare charge at the end of the commute and it just seems wrong to have more battery operated systems running independently.

The DC-DC converters I have are a hybrid design that switch at 400KHz and boast 80% efficiency. Input voltage is well above the 42 volt no load output of my battery pack. I found them on ebay and got a really good deal. These are not cheap to purchase new.

Andy

[norkmeister]

Any chance of a link to the switch mode DC converters?

I have a friend who has a Phd in robotics modifying this one
http://www.altronics.com.au/index.asp?area=item&id=K1010
to accept my 42V input voltage.

The reason I am using this is that I am planning on building one of these:
http://www.autospeed.com/A_109714/cms/article.html

I have the normal 2 x AAA flashers for visibility.  These last 200 hours anyway, so there is no issue with supplying batteries.

[ahend]

I have a DC-DC converter you may be interested in. Input range is 36 to 72 volts. It outputs +12 & -12 volts, and is capable of sourcing 1250ma (15 Watts). This unit switches at 200kHz with 84% efficiency. Load regulation is around 1%, with an output ripple of 75mv peak to peak. The device is manufactured by Fabrimex with a model number ECW48-121230C. Here is the datasheet. If you need other (smaller) voltages, run it through an appropriate regulator IC.

These were pulled from a fan control system that was purchased on ebay. I could pass one along at a very good deal.

The headlamp project you listed is very sweet, nice clean build. Very interesting.

Andy