[PSUBS-MAILIST] PWM

Fri Mar 31 22:25:48 EDT 2017

Hi Rick,

Yes, you need to match them and the assortment of drivers is quite
bewildering. I knew nothing of this myself just a couple of weeks ago, so
I'll try and summarize my selection logic but if anyone more knowledgeable
finds me in error, please do jump in. I haven't even received my drivers
yet, so my choice is untested.

Generally these drivers are either "step up" or "step down" devices,
meaning that they take the battery bank voltage and adjust it upward or
downward depending on the voltage required for your specific LED. Not all
LEDs of the same output have the same voltage requirement, so I can't
provide a standard voltage for 10K lights and you will need to look that up
on your LED specs. In most cases it should be clear which of those two
varieties of drive you need, so deciding whether you need a step up or a
step down driver I would say is the first cut at narrowing your choices. In
my case I had an odd situation, because the battery bank voltage was very
close to the LED voltage, and since the battery voltage will drop under
load and with discharge, I could find myself crossing the threshold from
stepping down to stepping up. There are a very few drivers that can step in
either direction as needed, but I did find a few.

To summarize then... Once narrowed down to step-up or step-down type, the
next thing is to look at is voltage ranges. Each driver will have an input
voltage range, which needs to cover your possible battery voltages, and it
will have an output range, which needs to cover the LED spec voltage. This
latter voltage is constant.

Then finally, there's a choice of driver current capacity. This is a
measure of how much power the driver can handle without burning out. Your
LED will tell you how many amps it consumes. A sub in the tropics is a hot
and humid environment with minimal ventilation, so I'm inclined to pick a
driver that is way over-rated to prevent it from heating up much. Bear in
mind you can also drive multiple lights off one driver if their combined
current is within the driver's current capacity.

As for dimming capacity, most drivers seem to have two pots, one for output
voltage and the other for output current. These controls should allow you
to dim the lights, but from what I saw they are typically small components
on the board, and not something intended for manipulation by the end user
on the fly. It may be you could replace a miniature trim pot with one on a
cable, mounted on the face of your enclosure, but you would also need to be
careful with the adjustment range. You would not want a knob that burns out
your lights if you turn it a little too far.

Hope that helps, but realistically you might find it'll take a day or two
of research to narrow things down.

Best,

Alec

On Thu, Mar 30, 2017 at 1:49 PM, Rick Patton via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Thanks Jim and Alec,
>
> Do i have to be concerned about matching the PWM to the specific LED array
> I buy as there are so many out there. If so, can someone help me do the
> match up as I have NO electrical back ground. I do want to be able to dim
> the lights from 10,000 lumans down as much as I want as there will be times
> where I won't need that much and it will also be a power savings on my 36 V
> battery bank for my thrusters.
>
> Rick
>
> On Thu, Mar 30, 2017 at 1:37 AM, Alec Smyth via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>> Hi Rick,
>>
>> LEDs need a driver board to supply them with constant voltage and
>> current, and Cliff's design includes an on-board PCB, inside the light
>> itself, that does just that. The heat is dissipated by the housing, which
>> is aluminum and has cooling grooves. Personally I opted for a larger off
>> the shelf driver that will go inside the sub, because I didn't have much
>> ability to solder the surface mount components and didn't have the need to
>> miniaturize that was one of Cliff's design priorities. There are lots of
>> drivers available, and I got mine on eBay like so many other components of
>> the sub. This driver has a heat sink, but I don't expect it to heat up much
>> at all. See eBay item 302203712954.
>>
>> Best,
>>
>> Alec
>>
>>
>>
>> On Thu, Mar 30, 2017 at 7:24 AM, via Personal_Submersibles <
>> personal_submersibles at psubs.org> wrote:
>>
>>> Rick,
>>> He was referring to a Pulse Width Modulator to adjust the amount of
>>> power going to the lights.
>>> Jim
>>>
>>> In a message dated 3/29/2017 11:29:44 P.M. Central Daylight Time,
>>> personal_submersibles at psubs.org writes:
>>>
>>> Alec,
>>>
>>> I just met a guy in California that made his own underwater housing and
>>> LED lighting system for doing video and he is using an LED board that is
>>> about 3" square. He has built a PWM for it so he can dim it down and says
>>> it's a 10,000 luman 100 watt system that runs on 32 volts.
>>>  I don't know what a PWM is but he said that I didn't necessarily have
>>> to have one. I can step my thruster motor supply down from 36V but one of
>>> my concerns is how to get rid of the heat. He didn't seem to be too
>>> forthcoming with the system he built. I think the LED array was something
>>> like $15 each on Amazon. How are you controlling the heat in your housings
>>> and do you think I would need a PWM for my lite?
>>>
>>> Rick
>>>
>>>
>>>
>>> On Wed, Mar 29, 2017 at 3:34 PM, Alec Smyth via Personal_Submersibles <
>>> personal_submersibles at psubs.org> wrote:
>>>
>>>> My lights are done, I put them on Shackleton earlier today and they are
>>>> wired through the hull with penetrators. However, the wires end inside the
>>>> hull because I'm waiting for the drives to arrive, which will be installed
>>>> inside the sub. I was able to test them with a lab type power supply on a
>>>> table top, and must say these Bridgelux leds are like a little sun in a
>>>> can, I love them. These two lights I made are 5K lumens, and I already have
>>>> 10K lumen Bridgeluxes which I bought by mistake. So I'll test these, and
>>>> probably make another set with those more powerful ones. If I do, the 10Ks
>>>> will be the forward lights and the 5Ks will be oriented out to the sides
>>>> for "peripheral vision". A dimmable driver is sounding like a good idea, or
>>>> maybe just sunglasses!
>>>>
>>>>
>>>> Best,
>>>>
>>>> Alec
>>>>
>>>> On Wed, Mar 29, 2017 at 9:10 PM, Alan via Personal_Submersibles <
>>>> personal_submersibles at psubs.org> wrote:
>>>>
>>>>> Thanks Hank,
>>>>> Alec has been making good progress with Cliff's light.
>>>>> Last I heard 2 housings were being anodised.
>>>>> Any update Cliff / Alec ?
>>>>> Alan
>>>>>
>>>>>
>>>>> Sent from my iPad
>>>>>
>>>>> On 30/03/2017, at 1:30 PM, hank pronk via Personal_Submersibles <
>>>>> personal_submersibles at psubs.org> wrote:
>>>>>
>>>>> You will be our go to guy for lighting!
>>>>>
>>>>>
>>>>> On Wednesday, March 29, 2017 6:15 PM, Alan via Personal_Submersibles <
>>>>> personal_submersibles at psubs.org> wrote:
>>>>>
>>>>>
>>>>> Still building lights Hank,
>>>>> have built a couple of housings but are doing a third revision &
>>>>> hopefully this one will be perfect. I am pretty happy with how it's
>>>>> going.
>>>>> Am getting a different LED driver made up with PWM dimming.
>>>>> Got off the motor project temporarily as my brother wanted one of
>>>>> the lights for his boat. 😐
>>>>> Alan
>>>>>
>>>>> Sent from my iPad
>>>>>
>>>>> On 30/03/2017, at 12:35 PM, hank pronk via Personal_Submersibles <
>>>>> personal_submersibles at psubs.org> wrote:
>>>>>
>>>>> Alan,
>>>>> Are you back to work on your motor?   or are you still building lights?
>>>>> Hank
>>>>>
>>>>>
>>>>> On Wednesday, March 29, 2017 4:44 PM, hank pronk via
>>>>> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>>>>
>>>>>
>>>>> Thanks' Greg
>>>>>
>>>>> Alan, my answer is who cares if some water gets between the seals.
>>>>> The important part is to keep the oil inside the motor.  When the motor
>>>>> starts up at the surface, there is significant centrical force that pushes
>>>>> the oil out with the seal in its original orientation.  I should actually
>>>>> remove one of the seals and just have one seal holding oil in, just like a
>>>>> submersible well pump has.  Those pumps are VERY reliable.  Now having said
>>>>> all this, I could be wrong ;-)   Stay tuned for test results.
>>>>> Hank
>>>>>
>>>>>
>>>>> On Wednesday, March 29, 2017 4:31 PM, Alan via Personal_Submersibles <
>>>>> personal_submersibles at psubs.org> wrote:
>>>>>
>>>>>
>>>>> How are you doing that Hank?
>>>>> Are you compensating the gap between the two seals?
>>>>> Otherwise you are in the same situation as the Minn kota motors
>>>>> where one of the two seals will fail when you go beyond it's depth
>>>>> rating.
>>>>> Cheers Alan
>>>>>
>>>>> Sent from my iPad
>>>>>
>>>>> On 30/03/2017, at 10:40 AM, hank pronk via Personal_Submersibles <
>>>>> personal_submersibles at psubs.org> wrote:
>>>>>
>>>>> Greg,
>>>>> Good points, but I personally am not ready to give up on oil filling.
>>>>> I have reversed one of the two seals in my new motors for Elementary.  One
>>>>> seal keeps the oil in and one seal keeps the water out.  I am confident
>>>>> this in addition to the compensation system will make for a clean leak
>>>>> proof set up.  The ice is off the lake by my house, so my test lake should
>>>>> be open in a week or so.  I will know then if my idea works.
>>>>> Hank
>>>>>
>>>>>
>>>>> On Wednesday, March 29, 2017 7:03 AM, james cottrell via
>>>>> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>>>>
>>>>>
>>>>> I have to say, I no longer think that WD40 is the best for
>>>>> compensating things underwater. Over time it causes plastics and rubber to
>>>>> harden and become brittle.
>>>>> Silicone oil is better but the other problem with oil compensation in
>>>>> general is that the smallest drop/leak makes a very visible oil slick
>>>>> around your sub (not good). Most guys are using trolling motors and they're
>>>>> not really tight enough to hold thin oil without leaks.
>>>>> Back in the 90s I was using air compensation- and it actually worked
>>>>> really well. As far as I know, Karl Stanley has also been using air
>>>>> compensation for a long time without problems.
>>>>> It's a clean system that's not hard to set up and a small bottle of
>>>>> air lasts for many dives.
>>>>>
>>>>> Greg C
>>>>>
>>>>>
>>>>> ------------------------------
>>>>> *From:* "MerlinSub at t-online.de via Personal_Submersibles" <
>>>>> personal_submersibles at psubs.org>
>>>>> *To:* Personal Submersibles General Discussion <
>>>>> personal_submersibles at psubs.org>
>>>>> *Sent:* Tuesday, March 28, 2017 12:55 PM
>>>>> *Subject:* Re: [PSUBS-MAILIST] WD - 40
>>>>>
>>>>> On a brushless motor it will maybe work with mineral oil.
>>>>> On motors with brushes I have bad expierence with that.
>>>>> Mineral oil is a big problem in a lake if a motor is even a little
>>>>> untight.
>>>>>
>>>>>
>>>>>
>>>>> -----Original-Nachricht-----
>>>>> Betreff: Re: [PSUBS-MAILIST] WD - 40
>>>>> Datum: 2017-03-28T17:15:59+0200
>>>>> Von: "Brian Cox via Personal_Submersibles" <
>>>>> personal_submersibles at psubs.org>
>>>>> An: "Personal Submersibles General Discussion" <
>>>>> personal_submersibles at psubs.org>
>>>>>
>>>>>
>>>>>
>>>>> Hi Carsten,
>>>>>                         I did a small test trying to light the WD40 on
>>>>> fire.  It's not as flammable as I thought it would be.  I think they have
>>>>> improved it's non-flammability with new formulation. It's still somewhat
>>>>> flammable however.
>>>>> I will be using a light mineral oil in my motors.
>>>>>
>>>>> Brian
>>>>>
>>>>>
>>>>>
>>>>> --- personal_submersibles at psubs.org wrote:
>>>>>
>>>>> From: "MerlinSub at t-online.de via Personal_Submersibles" <
>>>>> personal_submersibles at psubs.org>
>>>>> To: Personal Submersibles General Discussion <
>>>>> personal_submersibles at psubs.org>
>>>>> Subject: Re: [PSUBS-MAILIST] WD - 40
>>>>> Date: Tue, 28 Mar 2017 07:22:02 +0200 (MEST)
>>>>>
>>>>> Heat Vapor is may a problem with WD40.
>>>>> May ensure that the compensating back is big to handle that..
>>>>> We change to silicon oil for that reason.
>>>>>
>>>>> vbr Carsten
>>>>>
>>>>>
>>>>>
>>>>> -----Original-Nachricht-----
>>>>> Betreff: [PSUBS-MAILIST] WD - 40
>>>>> Datum: 2017-03-28T04:56:46+0200
>>>>> Von: "Brian Cox via Personal_Submersibles" <
>>>>> personal_submersibles at psubs.org>
>>>>> An: "PSubs" <personal_submersibles at psubs.org>
>>>>>
>>>>>
>>>>>
>>>>> I just ran one of my motors filled with the WD40.  It seemed to be
>>>>> very happy.  I mainly just did it to clean the carbon build up out of the
>>>>> motor.  I was surprised how sealed the motor was, it is open at one end
>>>>> where it mates to the gear box.  I was able to fill it up without it
>>>>> leaking out anywhere.  That could be an issue later when I want the mineral
>>>>> oil to fill all the voids.  I might need to actually drill some holes to
>>>>> get some circulation .
>>>>>
>>>>>
>>>>> Brian
>>>>> _______________________________________________ Personal_Submersibles
>>>>> mailing list Personal_Submersibles at psubs.org
>>>>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>>>>> 
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>>>>>
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>>>>>
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>>>>>
>>>>
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>>
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