P7 headlight project from newbie

[cyclopsed]

Hi all, newbie here.
Sitting in Luxembourg (somewhere between Germany, France & Belgium)

Just giving some info about my project.

First of all: thank you to every one having given contributions (text, images, drawings, links) connected to fitting, cooling, P7 & driver related topics, found answers to nearly every question.
Thanks again : ))

Trying to do a project for a caving headlight that shall be rather cheap, simple and based upon ready-to-use components.

Parts:
- SSC P7 DSXOI D-bin
- 8X AMC7135 DRIVER (Kaidomain SKU: S004338)
- so called Nano-Dim V2, 0-100% dimmer (found on eBay Germany), look for "nanodim"
- recycled Mag-3D head, the body isn't anymore :s
- heat sink for Mag
- P7 Al-reflector
- batteries:
- actually on the test run: 3x 1.5V alkaline on NiMH in series (4.8V downwards)
- later: 4x 1.2V Eneloop in series, they will fit into the rear battery pouch on the helmet
- maybe: designing a battery pouch for the helmet taking 8 Eneloops: twice 4x 1.2V Eneloop in //

Work so far:
Soldering, wasn't a problem.

Test run:
- it's bright, I still see stars : ))
- no heating observed in any part, weird, isn't it?

Problem encountered:
I opted for the trim pot (10K) step less dimming alternative for the NanoDim board.
Works to a certain degree: dimming from 0 to nearly 5K (50%) is OK, P7 becomes brighter, but triggers at around 50% immediately to 100% brightness. Can't dim back to 0%, have to switch off, turn the pot back to +/- 5K or less and switch on again.
I guess that something is overdriving, but what ? 8-I

ToDo's:
Fitting the assembly into the Mag head, water tightening it & fixing it onto the helmet.
Meaning:
- cutting some aluminium foil (better: copper), bending it & fix it with components within head, not that easy, there in no bottom in the head.
- finding a (good) solution to fix the head to the helmet

That's it for the moment.

 

[Magic Matt]

What input voltage does the driver need to maintain full output? It sounds like it may be dropping out of regulation because there's just not enough voltage going in, so you're seeing the result of it suddenly going into Direct Drive. If you're feeding it 3 eneloops (3.6V) then that's ok at lower power, but you'd probably need to feed at least over 4V to be regulated output at full brightness. The LED needs 3.6V for itself, and the driver etc. will not be 100% efficient.

 

[cyclopsed]

What input voltage does the driver need to maintain full output? ...

Good question, seems I have to learn a lot.
I didn´t find anything about that, just that the driver is rated from 2.7 to 6 V input, or did I miss somewhere a spec sheet? .
The driver drop current is around 0.5V
Batteries level was at at 4.5 to 4.6V (checked and made sure before the test that it was not more)
The dimmer is working with 3.5 to 24V, nothing found here about a additional drop current.
Or may there have been a battery ralated current drop under charge when I turned up to over 50%?
I was using NiMHs.
Hmmm, rechecking tomorrow eve.

 

[cyclopsed]

Ok, they were alkaline
I ordered Eneloops, they'll fit into normal 4xAA battery holders for the test phase.
Casing is in progress. I won't choose a milled casing, but cut Al-tubes that will fit one into the other. This at least for a first prototype. It'll be modular and easier to adapt to new or alternative parts.
Pictures will come soon.

 

[cyclopsed]

Eneloops arrived
4 in a battery clip >> 4,8V
connected
P7 oscillates at higher dim (higher resitance) position
oscillation changes to a more steady light at lower dim position
no dimming back possible unless switched off and back on.
:duh2:
does any one have an idea what happened?
hints?

TNX a lot

c