bb750 and 4C

Lichtgestalt · Jul 10, 2003

I'm planning to build a bb750 in my (already built) 3D-5W-Mod.
Since now I have driven it with 6AAs.
Is it a good idea take 4 C's now ?
How long would the runtime be then?
and would the lifetime of the LED be shortened (extremely)?

Another thing i don't get:
On the wiring-pics (link at shop) there are only 3 different connections described.
I'm not really into electronics but don't you need 4 connections -
2 for the Led an 2 leading to batteries.
thx

dat2zip · Jul 10, 2003

On the wiring diagram, J6 is both the LED - and the battery Ground Connection.

6AA with a BB750 is basically DD. The converter board is doing nothing.

The 5W is specified at 700mA. The BB750 will overdrive the Luxeon by a small amount. If you have the Luxeon heat sinked well, you will have no problems or shorten the LED lifetime rating.

Wayne

Lichtgestalt · Jul 10, 2003

thx
but 4C's will do it, right ?

dat2zip · Jul 10, 2003

4C is a great configuration. Any 4 standard cells or two 123s are the ideal battery configurations for the 5W. (6V)

Any two standard cells or a single 123 for a 1W is the prefered configuration. (3V)

shankus · Jul 10, 2003

[ QUOTE ]
dat2zip said:
Any two standard cells or a single 123 for a 1W is the prefered configuration. (3V)

[/ QUOTE ]
Regarding this, Wayne, I have a question. With the MadMax, the max Vin is stated as 3.1V. I have run a MadMax on two lithiums, for a brief time, and after thinking of it, I measured them at 3.6V.

I seem to remember posts of members saying they run the MadMax from lithium cells. Is it dangerous to the BadBoy / MadMax?
Another reason I ask is that, it seems eaier to find 1/3 AA size NiMH, than it is to find ½ AA. In a single cell M³, with MadMax, three 1/3 AA cells may be an option, as well, at 3.6V.

What do you think?

dat2zip · Jul 10, 2003

Shankus,

Anytime you push Vin over Vf you are in risk of going Direct Drive. Where the actual DD transition is a couple of tenths of a volt over Vf.

The voltage limit on the IC is around 6V and 3.6V is within the 6V IC voltage range.

I put 3.1 as a specification that I can assure will always work for the 1W Luxeon (not including Amber and Red).

Remember, that most batteries will sag under load. On the 3.6V, I would think that when powering the module that the voltage would be more like 2.9V or less. The voltage sag could be dramatic depending on the battery chemistry.