25-45VDC capable driver for two Cree Leds

[Misterbean]

i need a driver for a golf cart lighting system. The batteries are ran in series to power the golf cart and produce almost 37 volts. i don't want to run off of just one of the batteries and i don't want to run them parallel because they are already run in series and it would use too many wires and would clutter everything up. i am planning on running either two cree q5s or possible 2 ssc p4s. i want to push them between 800ma and 1000ma.

I need the varied voltage range because i don't want them to be blown when it is charging if the switch is flipped on. and i want them to be able to give light even if the batteries are fairly well drained. a bigger voltage range would be fine as long as it can handle what i put down.

 

[panic]

LM2576HV-ADJ is a good choise.
I've made a driver working under 12~52V DC supply with this chip.
The efficiency could be higher than 80% with 2 cree in series at 700mA or more.
The max output may be up to 3A. :thumbsup:

 

[VanIsleDSM]

With the input voltage that high you need good quality capacitors which aren't cheap. I don't imagine there's a commercial product that can do what you'd like, but if you find one, that's your best bet, as mass production will obviously make it cost less than a custom solution.

If a custom solution ends up being your only option, I could build you a custom switching buck driver if you like. Dropping from 25-45V to 7.2V is quite a bit, but I could still keep the efficiency up around 85%.

If you're really concerned about efficiency though, it would be better to run 4 emitters @ 350mA for roughly the same amount of light. Not only will the driver be more efficiency not dropping as much voltage, the LEDs themselves will be more efficient too. But.. that might not be a huge priority.

 

[Misterbean]

thanks for the advice. efficiency is not really an issue as the batteries have huge capacity. i would like a bolt on solution. i don't mind soldering things and i'm decent at it but i would rather just put it between the batteries and the crees and turn it on.

 

[marschw]

Maybe you could wire the inputs of two of these in series, but use the output of each for 1 light? The comments suggest that the output is about what you'd want. You'd need 3 in series, or another way to drop the voltage, to hit the high end of your input range, though.