[PSUBS-MAILIST] PSUBS light project status

Sun Jul 3 13:36:39 EDT 2016

Alec, while I like concept of KISS in general, I am not sure you would be
happy running this LED off a 36vdc bank without a driver due to the light
lumens variation with voltage.

 The light intensity and current are strong functions of the forward
voltage.  When the driving voltage drops from 38 to 35.1 vdc, the lumens
drop from 10,590 to 2846(27%) and the current drops from 2.1 amps to
500mA.  So as you start dropping the forward voltage the light get dimmer
and dimmer.  My guess is the below 35.1, it just continues to get dimmer
and dimmer.  We really need a LED driver like the one Ken specified that
will hold a fixed current regardless of dropping supply voltage.

On Sun, Jul 3, 2016 at 8:08 AM, Alec Smyth via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Hi Cliff,
>
> You got the attention of Captain Quaker there, as I too am running a 36V
> bus and the simplest most rugged driver is no driver. Since my boat hasn't
> been in the water yet I don't know what voltage drop I'll see at hard
> throttle, but in my experience the lead foot only comes down on the surface
> where I don't particularly need dive lights. When dived, the thrusters are
> just ticking over. Do you know what would happen when the voltage falls
> below 35.1? If the lights just go a bit dimmer, that might be fine. If its
> a step function on the other hand and they just go out altogether, then
> obviously not so good.
>
>
>
> Best,
>
> Alec
>
> On Sat, Jul 2, 2016 at 4:50 PM, Cliff Redus via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>> Alan, my boat has the propulsion buss at 36VDC nominal and everything
>> else on the 24VDC buss.   My exterior lights run of the 36VDC buss.  The
>> voltage range for 36V buss is 30-40vdc, fully discharged to fully charged.
>> If I Iook at the specs on the 10K Lumen Bridgelux, the driving voltage
>> requirement is 35.1V to 40.4 V with 38V as nominal.  So I could in theory
>> run this LED array without any driver at all but every time I hit the
>> throttle, the lights would dim.  I need a constant current LED driver that
>> holds the current to 2.1 amps.  Like you I have been looking for OTS led
>> drivers but have not been able to find one that meets the specs outlined in
>> Ken M. spec and are small enough to fit in as tight enclosure.
>>
>>
>> Cliff
>>
>> On Sat, Jul 2, 2016 at 3:05 PM, Alan via Personal_Submersibles <
>> personal_submersibles at psubs.org> wrote:
>>
>>> Cliff,
>>> what voltage are you running on your sub?
>>> You can generally run these leds at a lower voltage & it is
>>> beneficial to them. If you have a bench top power supply that goes to
>>> 36V, you can
>>> slowly power up the led without a driver & check if it is bright enough
>>> at 36V. Don't
>>> do this for more than a second or so or you may destroy the led. I am
>>> having a 48V
>>> system, but the choices in electronics that are compatible, dramatically
>>> drops over a 36V system.
>>> I have looked at just about every off the shelf led dc driver on the
>>> planet.
>>> cheers Alan
>>>
>>>
>>>
>>> Sent from my iPad
>>>
>>> On 3/07/2016, at 7:03 am, Cliff Redus via Personal_Submersibles <
>>> personal_submersibles at psubs.org> wrote:
>>>
>>> This LED driver will not work for the 10K lumen Bridgelux LED as it
>>> needs 38V forward voltage , 2.1 amps and 80W.  This driver can only get up
>>> to 36V.
>>>
>>> Cliff
>>>
>>> On Fri, Jul 1, 2016 at 11:39 PM, Alan James via Personal_Submersibles <
>>> personal_submersibles at psubs.org> wrote:
>>>
>>>> Alec,
>>>> I have been working on a light housing. Have attached a dwg but it is
>>>> not finalized.
>>>> I would have had it completed but have been waiting a Month on a
>>>> replacement motor
>>>> for my lathe :(
>>>> I am using a square 50W LED, but you can get 60 & 80W LEDs the same
>>>> size.
>>>> I am NOT putting the driver in the light housing, it ends up sitting at
>>>> the back of the LED
>>>> where there is a massive amount of heat generated from these high power
>>>> LEDs.
>>>> Keeping the driver in the hull makes it easy to change out if it fails.
>>>> I am going with an acrylic lens & oil compensated. I would have liked a
>>>> borosilicate pressure
>>>> resistant lens but it was going to cost $100-+. Also if there is a leak
>>>> with a pressure resistant
>>>> housing, electrolysis can pressurize it with hydrogen gas.
>>>> I am not using a reflector as they don't seem to do anything with these
>>>> big LEDs. They are really
>>>> rows of little 1W LEDs,10X6 for a 60W. So you get light being emitted
>>>> from either side of the inch
>>>> wide emitter, that is hard to control, especially when you are wanting
>>>> an  80 degree wide angled
>>>> flood light.
>>>> My design also revolves around local stock aluminum tube sizes.
>>>> The LEDs are around 30 to 36V. I am using these as drivers. $4.64 US,
>>>> not bad.
>>>> Alan
>>>> Constant Voltage Constant Current DC-DC Power Module for Arduino
>>>> <http://www.dx.com/p/5a-constant-current-led-driver-module-battery-charger-red-433947#.V3dE1bh96Uk>
>>>>
>>>>
>>>> $ 4.64
>>>> Constant Voltage Constant Current DC-DC Power Module for Arduino
>>>> I like this from DX. Find the cool gadgets at a incredibly low price
>>>> with worldwide free shipping here.
>>>>
>>>> <http://www.dx.com/p/5a-constant-current-led-driver-module-battery-charger-red-433947#.V3dE1bh96Uk>
>>>>
>>>> ------------------------------
>>>> *From:* Alec Smyth via Personal_Submersibles <
>>>> personal_submersibles at psubs.org>
>>>> *To:* Personal Submersibles General Discussion <
>>>> personal_submersibles at psubs.org>
>>>> *Sent:* Saturday, July 2, 2016 1:41 PM
>>>> *Subject:* [PSUBS-MAILIST] PSUBS light project status
>>>>
>>>> Hi gents,
>>>>
>>>> I have an almost-ready sub but no lights, so was wondering whether to
>>>> make them per the PSUBS-designed model in the community projects section of
>>>> the website. I'm in awe of those drawings! However, they show a printed
>>>> wiring board that is a placeholder for a part still to be designed. I was
>>>> wondering if that might have happened, or if there might be an ETA?
>>>>
>>>> Thanks,
>>>>
>>>> Alec
>>>>
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>>>>
>>>>
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