Upgrade: Technisub Alulight 20W halogen to 3xP7

[imnata]

Boost is not possible because the Iin limitation of 2.8A.

If I my assumption is correct, then 2.8A limitation is not relevant, because
MC-E leds can be wired 2P2S or 4S1P. So in theory I would only need 1,4A or 0,7A out of a driver.

Nevertheless you have an Pin of round about 33-35W. Your batterie will do this?

7,2V x 4,1Ah ~ 29.5Wh so with this set-up the burn time would be under 1 hour.
Although I looked at my battery pack and I think I could squeeze in one extra cell (8,4V x 4,1Ah ~ 34,4Wh).

Later on I think it would be possible to replace 6S1P NiMH battery pack with a LiIon (or LiFe) 2S3P battery pack for longer burn time. Again this is theory. I hope you guys will correct me if I'm wrong.

 

[Goldigger]

Which leds are you going to use and how many?
If your using 3 MCE's 2S2P @ 1400mah wire your battery pack to a suitable voltage
Use a Maxflex driver, just set it to 1400ma current with a momentary switch then remove it and wire your normal switch to it..
Maxflex will work from 2.5v are you going to use protected or non protected 18650's..

Just an idea, but it seems you know what your doing anyway.

Have a read through this thread 4 P7's 8 x 18650's HipCC driver
https://www.candlepowerforums.com/threads/213694

 

[DaYerk]

If I my assumption is correct, then 2.8A limitation is not relevant, because
MC-E leds can be wired 2P2S or 4S1P. So in theory I would only need 1,4A or 0,7A out of a driver.

The limitation is about the input current. P=UxI. - If I has a limitation (2.8A), you have to increase the voltage to gain the power.

This is why the chart shows a minimum voltage of 11.5V for three LEDs (P7 or MC-E).

Pin = Uin x Iin = Pout = Uout x Iout = constant

 

[imnata]

@Goldigger

Now I'm thinking about using 3 x MC-E insted 3 x P7, because they seem more versatile. They allow different wiring, like DaYerk suggested. (4S1P,1S4P or 2S2P)
I don't think maxflex driver will work...

>>>TaskLED Note: it is not recommended to run maxFlex5 at >3A input current, the above tests were to demonstrate the reduced efficiency at the higher input currents.

I calculated an input current of 4,6A. So for now I think Hyperboost is a better choice.

>>>TaskLED note: Now, Input_current should be around 5A or less for optimal performance of Hyperboost. When running at high input power it is recommended to use the supplied thermal pad material to mount Hyperboost to a heatsink.

are you going to use protected or non protected 18650's..

Some over-discharge protection would be nice, but I haven't seen any PCBs for this purpose. Haven't even looked to be honest. Do NiMH battery packs usually have protection?

This is why the chart shows a minimum voltage of 11.5V for three LEDs (P7 or MC-E).

Yes it does for 3 LED in series and each LED has the 4 dies wired in parallel (1S4P)! If you just look at the dies you could say all 12 dies are wired 3S4P. In this case Vf ~ 11V and If =2,8A

However with the MC-E I can wire each of the 12 dies separately if I want (or in different combinations)
So if I wire 3 LEDs, that have their dies wired 2S2P, in series....
or lets say the 12 dies are wired 6S2P. Then Vf ~ 21,6V and If = 1,4A.
Assuming that a single die of a MC-E needs a Vf ~ 3,6V and If = 700mA

 

[Goldigger]

Why not loose a cell, wire them all in series to give 18.5v @ 2500mah thats under the 3 amps?
The maxflex should be ok.. on a fresh charge protected cells will be 21volts the leds will need 22.2 volts if wired 2S2P (if Vf is 3.7 per die), so its close but the maxflex should still boost fine..
Use the dx 18650 protected cells, there cheap and the best value I think you can get.
http://www.dealextreme.com/details.dx/sku.5790
You can solder them as a pack. There was a thread on here on how to do it without damaging the cells.

You should get over 1hour burn time..

 

[imnata]

I've done some reading on DIY LiIon battery packs and I think it's more of a no go. If I decide for LiIon then I'll buy a pre-made battery pack with PCB and a suitable charger.

if Vf is 3.7 per die

In CREE MC-E data sheet it says:
Characteristics - Per LED die
DC Forward Current - 700mA
Reverse voltage: 5V
Forward voltge @ 350mA: typical 3,2V, maximum 3,9V
Forward voltge @ 700mA: typical 3,4V

 

[imnata]

Upgrade: Technisub Alulight 20W halogen to ??? (XP-G)

Hi everybody,
unforunately this project was on hold from february till recently. I simply didn't have time for it.

The plan hasn't changed much it just got modified a little bit over time . As you know I started with 3 x SSC P7 then I switched to 3x Cree MC-E because of the flexibility
that it offered... and now I'm considering XP-G LEDs. (think I found some nice optics/ reflectors for it)

I already looked into this option a bit.
In the Alulight housing I would be able to place 7 XP-G leds on star PCBs.

This set-up would (theoretically);
- put out more light than 3xMC-E (less than 3xP7),
- have a longer burn time (more than 1 hour at max output insted of less than one hour)
- cost less than 3xP7 or MC-E

I still plan on using NiMH battery pack 7,2V 4,1Ah and maybe add an extra cell > 8,4V
Havent decided on which driver too use yet, maxflex or hyperboost.

In technical information for maxFlex it says that it's not recommended to run maxflex boost driver at input currents higher than 3A.
With a 7,2V battery pack and 7 x XP-G leds I get an input current of 3,64A (or 3,1A if I upgrade the battery pack to 8,4V)

The heat dissipated from this setup would be around 3W.

Beyond 2W of dissipation thermal management becomes more challenging and it is highly recommend that the thermal protection be enabled in the menu system. Start with 50°C in the menu and refine as needed. A thermal path from the top of the inductor will enable reliable operation at up to 3.5W dissipation.

So is this excesive heat a big problem (underwater)?

In this aspect the hyperboost is better (higher efficiancy, input current is < 5A) however If I want dimming control, then I need to buy d2flex aswell.

Another option is to reduce the nummber of leds from 7 to 5 XP-G and stick with maxflex?

For the XP-G I planed on using Ledil Regina reflectors (round 19mm reflector)

 

[imnata]

No comment's?:wave:

I've done some extra reading (maxflex thermal guide- d'oh and some other threads) so I guess that in my case 7x XP-G with maxflex is pushing it ... because of my battery pack(7,2V or 8,4V is not much of a difference)

Even with proper heat-sinking and underwater I think it would be a problem??

What do you guys think about Regina reflector for Xp-G's?

 

[jspeybro]

No comment's?:wave:

sorry, not (yet) familiar with it...

What do you guys think about Regina reflector for Xp-G's?

Interesting. I just ordered some ledil LXP RS lenses, pity that I didn't see this one earlier, I could have ordered one at the same time.
angle is ±5° so 10° is the full angle.

The LXP is 11° so slightly larger, but the light distribution seems better if you compare the datasheets.

 

[imnata]

The LXP is 11° so slightly larger, but the light distribution seems better if you compare the datasheets.

Size matters
They are too big, there is no way to fit 7 of them in fi 60mm housing.
Five of them is no problem, 6 or 7 is impossible.

 

[imnata]

What about this set-up:

If I use 6 x XP-G in a 2S3P set-up, then Vf=6,6V and If=3A which means I could use a buck driver like H6CC?

Have to do some search if somebody already did something similar.

 

[Doh!Nut]

I finished my similar light using 4*18650 and 3 P7 27mm reflectors
I just finished my first dive trip with it and I was pleased with how it performed.

 

[imnata]

Nice work.
I can't believe what kind of switch they used in the original lamp
Very simple and effective but still...

Did you do some calculations for the heat sink or did you just use the biggest piece of aluminium you could squeeze into the lamp?

 

[Doh!Nut]

Hi

I did not do any specific calculation for the heatsink but I knew that to get the heat from the LED to the lamp housing, the edge of the heatsink needed to be thick.
The light is not too heavy, but there is scope to hollow out the underside of the heatsink to reduce some weight if needed.

The new switch is a micro switch, but I did not put a spring return on it so it is a little too easy to do a "press" rather than a "click" which puts the driver into flashing mode. This was fine for me, but I lent the light to a friend and with instructions via my wife and he spent the first 5 mins with a strobing light.

 

[imnata]

That's a good one.

I just started reading about heat sinking these days and I'm already beginning to have a headache...
Can you tell me what's more important for a heat sink in a dive lamp the volume or the surface of the heatsink, that is touching housing of the lamp.

 

[lucca brassi]

oops

 

[alpg88]

it pbly be a lot easier, and may be even cheaper, to buy uk aquasun led.
buddy of mine bought one, and he loves it, he says it kills his hid uk light cannon.

 

[imnata]

I agree. But there are other reasons for doing this upgrade.