P7 for Mountain Bike Use - Check

[MrLee]

Hi All,

Apologies if my questions seem trivial, I just wanted to check a few things before I spend some money.

I'm thinking of building a custom light for mountain biking, I am thinking of getting a P7 (http://www.dealextreme.com/details.dx/sku.12721) from DX,
would the driver they have - (http://www.dealextreme.com/details.dx/sku.20329) be ok with the following setup -

- I'm thinking of running 2 chains of (4 AA cells in series) in parallel, which would give about 4-5volt. Would this be an acceptable approach?

- I'm looking for a run time of about 2 hours. (i'm open to ideas).

- The last charger I made years ago was a simple NiCad one, how would I go about charging the custom NiMH or Lithium pack? - I'm guessing it is not straight forward - could someone point me in the right direction please? (is it best to resort to removable cells and use an off the shelf charger?

My last questions surrounds heat dissipation from the driver - As it has two boards, I am assuming this only needs mounting by the base - how would you mount the driver securely? Thermal grease doesn't look like it would work on its own?

http://www1.dealextreme.com/productimages/sku_20329_3.jpg

[Hotlinked image replaced by link - please read Rule 3. - DM51]

Is there anything else I need or should know about?

Thanks in advance.
Lee

 

[sortafast]

I made a very rough light I used on some night time DH runs this last summer (threw it together in 20minutes with some light bodies i had made and speaker wire I had laying around). It worked pretty good, but not sure on the run time. I would guess in the 1hr range. But I went direct drive off of 3 NiMH D cells. They were cheap Harbor Freight batteries, but they seemed to work well. Really though, if you don't mind spending the $$$ lithium batteries do a bang up job and you can build or purchase a pack that will be smaller and lighter than NiMH. Also with that board it looks like it will probably run better off of a bit more volts coming from your battery pack. But its really about the application and riding style. I was hitting some 20ft speed doubles at 11:30 at night so I needed max light. but if you are just XC riding 1-2 cree q5/r2's is more than adequate IMO. Or you could get a couple R4 XP-G's and really make some tiny little monsters. I want to get a 3 XP-G board from cutter and the 20mm carlco optic and make a housing that isn't much bigger, and run it off of a Fatman or maxflex with a LiFePO 6.4v pack. That would be fun.

Not sure if that helps, but thats what happens when my 2yr old wakes me up too freaking early in the morning.:tired:

 

[spankone]

http://www.candlepowerforums.com/vb/showthread.php?t=245642

my build

 

[T0RN4D0]

With 4 AAs in series you won't get even 1 hour runtime on max power, if the driver really does pust out 2.8A. More like 40 minutes at best.