Advice for modifying a 2D torch

ecotack · Feb 11, 2009

I was thinking about either a 3, 4 or 5 Cree R2 set up with preferably three light settings (say 100mA, 300mA and 700mA). The bit I'm struggling on is the batteries and drivers.

Battery choices would be 2 x D NiMh (2.4v 10Ah), 2 x 25500 Rechargeable Lithium (7.2V 5Ah), 8 x AA NiMh (9.6v 2.5Ah) or 6 x AA NiMh (7.2v 2.5Ah).

I doubt there is a single board I could buy that would run 5 emitters at 3 levels, so whats the best option? I'm starting to lean towards the 4 emitters and 2 x 25500 Lithium.

PCC · Feb 11, 2009

A D2Flex from TaskLED would probably work for you. You do need to keep in mind that you need to add the forward voltage for all of the emitters you plan on using then add at least one volt above that for the battery voltage you will need to drive it. For example, 3 LEDs @ 3.3V gives you 9.9V. 3 Li-Ion cells will give you 11.1V so this would be about perfect.

ecotack · Feb 12, 2009

Don't think I'd be able to fit 3 Li-Ion cells in unless I used cr123s.

After some more research I have found D cell sized Li-Ions (true 5Ah'ish), so I think I'll stick with two of them for the better battery life (the C sized ones only turned out to have less than 3Ah from reviews).

I was thinking about using 5 Cree R2s in parallel and using a 3A driver suitable for SSC P7 (seams to be a few designs around, most for one 3.7v Li-Ion though). Three 1A boards in parallel using 1, 2 or all 3 for the brightness levels may also be an option.

Any recommendations? I'll be putting an order in to DX and KD later :grin2:

PaulH · Feb 12, 2009

Hi Ecotac,

No specific recommendations, but just beware about ordering LiIon cells from the two suppliers mentioned. I have had D cells on order since November, and C cells since December. I am advised that the factories supplying them 'might' be back in production within the next couple of weeks. I'm not going to guess when I 'might' actually receive them, but I'm not holding my breath.

bretti_kivi · Feb 12, 2009

why parallel? more magic smoke - :poof:

- risk. Go serial. Add the voltages together; feed 5 x 3.25V crees 9,6V from 8 AA eneloops...

Bret

ecotack · Feb 12, 2009

bretti_kivi said:
why parallel? more magic smoke - - risk. Go serial. Add the voltages together; feed 5 x 3.25V crees 9,6V from 8 AA eneloops...

Bret

Won't I need a supply of ~17v to drive 5 emitters or possibly make my own step up driver? With them in parallel I can just use an off the shelf 3A driver designed for a SSC P7 or four 800mA drivers in parallel. I could use five separate boards (one each), but I would like a simple method of changing the brightness, either on the original switch or a second switch. If the modes on the 3 mode drivers would always sync then that may be a better route.

Hopefully if I buy all LEDs at the same time they will be from the same batch. After all most SSC P7s are driven in parallel, which are effectively 4 LEDs.

ecotack · Feb 12, 2009

PaulH said:
No specific recommendations, but just beware about ordering LiIon cells from the two suppliers mentioned. I have had D cells on order since November, and C cells since December.

They both have backlogs due to Chinese new year. Almost back to normal now at DX, not sure about KD though.

bretti_kivi · Feb 12, 2009

the Shark could do this, I think the Maxflex or fatman too, check the output / input and do the calcs. I was looking at doing lots of crees myself and drew the conclusion that 9AAs would be fine;

from http://candlepowerforums.com/vb/showthread.php?t=105492

================================================== ==========
A general rule of thumb to use the Shark.

1) Determine the number of LEDs you want to drive in series. Example: 4 Lux3s.

2) Determine the series voltage of the LEDs at the desired current. Example: 1A which means ~4V/LED and 4LEDs = 4 * 4V = 16V (approximately)

3) Determine the operating and min battery voltages using the total Vf output. Operating is > 1/2 output and min is approximately 1/3 Vout.

Operating should be greater than 1/2 of 16 Volts or a fresh battery pack should be 8+ volts.

At end of battery life your battery voltage should not drop below ~ 1/3 Vout or 1/3 of 16 = 5.3V

In this example a 9V stack of AAs batteries or a 12V stack of AA batteries would be fine for this example. What won't work is 2AAs, 4AAs since the current demand will approach the limit of the regulator.

Example 2:

Three low Vf LuxV. say you have 3 LuxVs with Vf of approximately 7V @ 700mA. That's 21V which is below the 22V open circuit protection (with J1 jumpered).

1/2 21V is 10.5V and 1/3 21 is 7V.

A 12V battery pack would suffice for this application. A 9V battery pack would be marginal for this application.

that should see you right. A shark is $55. A fatman should do something very similar for a bit less.

Bret

ecotack · Feb 12, 2009

Thanks Bret,
Looking at the fatman, using 2 Li-Ion should give me around ~650mA for five Cree R2s at an input current of 2A. Adding a trim pot for brightness control is tempting.

Can anyone suggest a good source for the fatman with reasonable delivery times to the UK?

ecotack · Feb 12, 2009

More research shows fatman won't work, the output voltage is to low. The MaxFlex looks like a good one to go for now.

bretti_kivi · Feb 12, 2009

taskled's delivery is excellent. I ordered a couple of D2Dims recently and they were here within a few working days (i think over the weekend). That's cool in my book.

Bret

ecotack · Feb 12, 2009

I got a quick reply from TaskLED when I asked about the maxFlex. He suggested two Li-ion would be inefficient. Looks like I'll need a 8AA to 2D adapter. Any suggestions for a source with good delivery to the UK?

bretti_kivi · Feb 12, 2009

https://www.candlepowerforums.com/threads/198633

tx101 · Feb 13, 2009

Hi Ecotack,
I am planning a similar build but with a 2C Mag and only three R2 emitters
powered by 2 x 18650.
I have all the parts except for the reflectors and the board .... being shipped as we speak

Threads that might interest you

https://www.candlepowerforums.com/threads/221819 (Will build a quad P4 for me

)
https://www.candlepowerforums.com/threads/154668
http://candlepowerforums.com/vb/showthread.php?t=169747
https://www.candlepowerforums.com/threads/174064
https://www.candlepowerforums.com/threads/168062

Hope that helps :thumbsup:

ecotack · Feb 14, 2009

bretti_kivi said:
https://www.candlepowerforums.com/threads/198633

I'd seen these and also the ones from sandwich shoppe. I was worried about having to boar out the torch, but when I tried 4 AAs they fit fine, so I came up with an idea for my own adaptor. I'll make 5 PCBs for the contacts (can't do double sided so need two for middle and top) with 4mm studding down the centre, which also carries the ground to the base. I'll also need to glue on some perspex 'shapes' to keep the batteries in place.

Slow part at the moment is the reflector and R2s, both on backorder. I've ordered the maxFlex, so should be able to test that on some Q5s.

Advice for modifying a 2D torch

ecotack

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