Stacking Micropucks, driving a 3W at 620mA

I was told it could not be done. I was told it could be done. So I had to try it. I ran two Micropucks in parallel, powering a 3W Luxeon Star.

Initial test: I hooked up the two Micropucks in parallel, powered from two Duracell alkaline D cells, powering one 3W Luxeon Star. Initial current is 620mA! /ubbthreads/images/graemlins/eek.gif This is from only two D cells, so that is excellent. I'm going to be doing a run test, showing current, Vin, Vout, time, etc, and will post results.

I am also going to test this with 3 D cells, powering a 5W. Perhaps someone will beat me to the punch on testing the 5W?

Micropucks are on sale on my web shopping cart right now, for only $10/each, as right now I have quite a lot of them on hand.

I received a tip from a customer about this doubling up, but it was in regards to powering the 5W. I had to try it with a 3W first.

(I posted here in this forum as this is more related to flashlight modifying.)

To be continued . . . .


Wayne j

Re: Stacking Micropucks

Cool. Would be awesome to do 3 of them, in a 2D body'ed light using 3C cells!! The extra voltage won't hurt them???
2D size light 5w using C cells!
Or 2C with 2Cs at lower current!

Re: Stacking Micropucks

My first thought is 'How is this different from paralleling batteries?'. I would be a little concerned about them sharing the load equally. An incandescent bulb or similar load would provide a set resistance which would look the same to both sources. I'm not sure that a diode would, however. There might be enough resistance in the rest of the circuit to help keep these equal. Keeping the wire lengths the same will help.

Are these PWM or other type of switching DC-DC converters? If so, I do think getting them to share a load equally can be a problem. A better solution might be to use one micropuck to control a transistor which would handle the high current. This is almost exactly like using a relay.

The micropuck could loaf along at 100ma. and the transistor could carry an amp or more (how small do you want it?) A cheap TO-220 size transistor (about the size of the micropuck) could handle 3-5 amps with the same heatsink like you need for the Lux3.

Maybe you should try to take current measurements on the setup you are using now.

Re: Stacking Micropucks

but using a transistor won't boost the voltage though.. thats what the micro pucks do so the luxeon can draw 350ma. It boosts it to whatever voltage is needed to get 350ma draw...

Re: Stacking Micropucks

You're right, Isaac, the transistor could be used to boost voltage OR current, but this would require both at once. Me bad.....let me think about this some more. RussH

Re: Stacking Micropucks, driving a 3W at 620mA!

I'm doing this on based on the type of circuit is used in the Micropuck. I won't say what it is, though.

Anyway, here are some initial results:

Time:_____Vin_____Vout_____Current_____IC temp
7:20am____2.739___3.315____620mA_______
7:35am____2.495___3.266____540mA_______97.5F
7:45am____2.495___3.264____520mA
7:55am____2.454___3.241____510mA
8:15am____2.380___3.226____520mA (Go figure?)
8:55am____2.257___3.220____480mA

After an 1 1/2 hours, still close to 500mA, not bad. /ubbthreads/images/graemlins/grin.gif

Inventors must be optimists. /ubbthreads/images/graemlins/grin.gif

To be continued . . . . .

Wayne j

Re: Stacking Micropucks, driving a 3W at 620mA!

Here's final results, using two alkaline D cells, and stacking parallel two Micropucks: /ubbthreads/images/graemlins/grin.gif

Time:_____Vin_____Vout_____Current_____IC temp
7:20am____2.739___3.315____620mA_______
7:35am____2.495___3.266____540mA_______97.5F
7:45am____2.495___3.264____520mA
7:55am____2.454___3.241____510mA
8:15am____2.380___3.226____520mA (Go figure?)
8:55am____2.257___3.220____480mA
9:20am____2.197___3.208____460mA
10:00am___2.136___3.196____450mA
10:20am___2.113___3.190____450mA
11:25am___2.028___3.171____420mA
12:55pm___1.918___3.149____390mA
03:15pm___1.764___3.114____350mA
05:20pm___1.140___2.954____170mA
End Test

Still giving useable light, but I lose patience after a while. Somewhere between 3:15 and 5:20, it dropped from 350mA to 170mA. Wish I knew when it dropped below the 300mA and 200mA threshhold.

Anyway, this to me is very impressive.

Presently I'm testing with three nimh D cells, 4500mAh. I'm using nimh because I'm out of new alkalines. I'll get some and continue testing. I'm running the 3W from the three nimh D cells. It is starting out at about 1,000mA. I'll add results later.

Stacking the Micropucks works great!

Wayne j