BB750 Input Voltage?

[Otokoyama]

The specs say Maximum Input Voltage 9V but Input Voltage Range (5W) ~4.0-6.2V.

If I drive a 5W with 5 NiMH cells (7V fresh), will anything fry, or will the emitter just be overdriven (i.e. direct drive) for the first few minutes?

 

[Rothrandir]

i believe you just need to keep it under the vf of the led.
any more can kill the converter i *think*

 

[dat2zip]

You can go above Vf by a few tenths of a volt. Beyond that you could damage the converter board. 7V is probably safe depending on the Vf of the 5W.

Wayne

 

[Otokoyama]

Thanks, for this response and in the other thread.

So it sounds like 6 NiMH cells would actually be too much regardless of what the Vf of the emitter is. Right?

 

[dat2zip]

6 NiMH is asking for trouble. NiMH hold their voltage well under load and a fully chaged NiMH battery is typically 1.4V or so. That would put the stack of 6 batteries around 8.4V which is well above the Vf of a nominal 5W LED.

I know that makes it harder on the battery arrangement and configuration.

The only other alternative is to use a step down with 6 batteries like the Downboy or use a stepup/stepdown converter. The wizard is a stepup/stepdown but cannot handle the power requirements of the 5W.

 

[LED]

Wow, I was planing on run the BB750 in a 6 C cell with a 1W. Is 6 C alkalines’ to much voltage? My understanding was that maximum 9V meant that 6 X 1.5 was ok

 

[LED]

K, I see that 3.1V is the maximum voltage for a 1W. What is the best way of getting the most light from the 1W/6C combination then?

Thanks!

 

[Chief_Wiggum]

Well, I would think that a Downboy would be the way to go. You can get the DB700 which will be plenty bright, but if you're feeling adventurous, you can but a DB blank and add the sense resistor yourself. Here's a table:

http://www.candlepowerforums.com/ubbthreads/showflat.php?Cat=&Board=TheSandwichShoppe&Number=317800&page=0&view=collapsed&sb=5&o=&fpart=1

 

[LED]

Chief Wiggam thank you, but I just don’t get it. I understand why I would need a DB vs a BB for my 9 volt project but I don’t get why a 400mA DB would be brighter than a DB700. I’m sure the answer has to do something with sense resistors, but I don’t understand. Is there a Down Boy blank tread for dummies somewhere?

Thanks,
Dave

 

[dat2zip]

Have a look at the calculator web page I created to compute the sense resistor and now it computes the estimated run time and suggested converter board as part of the run time calculation.

www.anlighten.com/shop/test.php

It is still in development. Use at your own risk.

Wayne

 

[LED]

Thanks guys, I think it's starting to sink in. What's the Battery Amp/Hr capacity for standard C cell alkaline?

Dave