Please Help an Electronic Idiot(batteries, etc.)

[InitialImage]

I could really use everyone's help/suggestions.

Here is my project and what I hope to achieve.

I'm going to start canoe racing again. A couple of the races are endurance races which require paddling through the entire night. I will be making a light specifically for this purpose.

I have some new collimators(tight beam for throw) for the k2 led. I'm about to order some k2 stars since I don't currently have any. I plan to hook them up to run at the same time and would like them to run at 1000ma. For ease of use(no charging involved) I just want to use regular alkaline batteries, especially since this light will only be used for some training runs and during the races themselves.

I need a runtime with a minimum of 9 hours. Preferably 10-11 hours. I have some nflex boards from Taskled and would like to hook up one of them to run the k2's at 1000.

I'm guessing D cells would be the best option.

I can machine and make about anything, but I'm and idiot when it comes to electronics which is why I need your help. I can follow directions to solder and set up everything, I just need to know where to start.

How many D cells would I need to use to get the runtime I want and how do you suggest I set them up? What kind of container/holder?

If you have any other suggestions other than what I've mentioned, please offer them..

Thanks a ton,
Jeff

 

[yellow]

if this goes in full darkness, a 1 W will be more than sufficient.
Try a Fenix L2 - running for 4 hours on just 2 AA cells - to get an impression.
weight and size should be considered, I think
Now Your runtime is a bit of a problem.
I would try to get a cheap host with 4 or 5 AAs and built a lamp with the drivers mentionned.
but if You want more light, then maybe a D-cell pack inside the boat is the option.

Dunno the N-Flex, when using badboys I am working the following:
1st, get the Led together with the heatsink, make the cell-pack, solder everything to the driver board.
Now have a small board with several resistors (the largest, 50 ohms, directly connected) soldered to the resistor part at the driver.
--> power up, led should run very low (50 Ohms, remember?)
now, with a wire at the resistor board, connect the lower values, till the desired output at the led (alternatively the desired current from the pack) is achieved.
--> use this resistor.
thats how my lights go.
(btw. usually 2 levels at least installed. If building by myself, why stay with just one level?)


some Options might be:
Petzl Myo XP,
Princeton Tech Apex (main beam on low)
Stenlight S7 (overkill)

 

[monkeyboy]

If you're looking for long runtime, K2s are not very efficient. U-bin luxeon III will produce the same light output at 700mA as a U-bin K2 at 1000 mA while consuming considerably less power.

On the water, you can never have enough light, you should consider using a few LEDs. I reckon you will need 2 D size alkalines per luxeon III or 3 per luxeon K2 to give the 9hrs runtime you are looking for. A lithium ion battery pack would be lighter and rechargeable.

 

[MoonRise]

Alkaline cells sag badly under load and with use the voltage just keeps dropping and dropping and dropping, so a driver board will try to draw more and more current, so the voltage sags more and more. You get the idea.

You are asking for 1 amp of current per light for 10 hours, so you need 10 Amp-hours plus. Allowing for driver or other losses and inefficiencies, you need 12-15 amp-hours of 'juice' per LED. If the voltage of the cell/battery matches close to the LED Vf, that is. If the cell/battery voltage is 'off' from the Vf of the LED (yes, I know you are using a driver board to get the -right- voltage and current to the LED) then we need to account for that as well. Because we really need to look at Watt-hours of power (volts x amps x time-in-hours = Watt-hours) but cells/batteries are usually not labeled in Watt-hours. So we have to back into the values based on current, voltage, and time and adjust as needed.

What are your time, money, weight, etc trade-offs and limits?

The nflex driver is a buck driver, so you will need to feed it voltage higher than the LED Vf or for multiple LEDs in series, higher than the sum of the Vf's for it to work in regulation. Max Vin for the nflex is listed as 24V, and Vin needs to be greater than the sum of Vf + 1.1V, and the nflex is listed as driving 1-4 Lux-III or 1-2 Lux-V at a time. And the minimum Vin for the nflex is 4V, so using 3xD-cell alkalines will drop out of regulation once the cells drop down to 1.3V each. Which will happen pretty quickly at a 1-amp load.

Simple, relatively inexpensive, but heavy would be a SLA deep-cycle marine battery. Put it in a battery case, wire it all up, pretty much done. Battery cost should be about $50-$100 or so.

Simple, much lighter than SLA, but more expensive would be a pack using different chemistry. Like NiMH, or Li-poly, etc. Battery cost could be $100-$400 or so.

And yellow, like monkeyboy mentioned, you can almost never have too much light when on the water. Sure, others can see that you have a light for a pretty long distance, but you need some serious lumen-ooomph to be able to actually -see- anything. The water just effectively sucks up an enormous amount of light.

Jeff, how many K2's or other LEDs do you want to use? And what Vf did/will you get? It does make a bit of a difference in figuring out how much battery you need.

If you are really-really set on using alkaline D-cells to run the LEDs for 10 hours, I think you'll pretty much need at least 4 D-cells in series per LED to just squeek by on the runtime you are looking for. Do you want to run individual 'light units', with cells, driver, wiring, and one LED per unit? Or do you want to run multiple LEDs off of one nflex with one 'power source'?

You have to give us some more info to help you get some more specific answers for you proposed task.

 

[InitialImage]

Since i wrote my original post I've decided that I will most likely use either sla battery/s or nimh. I think I'd rather have the rechargeable option. I was initially concerned about weight but I'm not worried about the weight option at this point. I've been out of the whole led loop for a couple of years so I wasn't sure about my best option.

I think what I'll do is restate what I would like to have and then ask for "what would you do if it were you" suggestions.

I will wear a headlamp but I'm not figuring that into my canoe light setup.

I want two lights mounted to the front of the canoe. I'll have them wired to different packs that are mounted within a bulkhead in the front.

Light number 1: This light is to be turned on at dark and will burn constant all night long.

Light number 2: This light is to be turned on/off as needed and the intent is to be very bright. Don't need an all night runtime.

What setup do yo suggest for my target goals?

Thanks a bunch.

 

[monkeyboy]

If money was no object, I would get the Lupine Edison 10. It's 10/16W li-ion rechargeable HID bike light.
http://www.rutlandcycling.com/ProductDetails/mcs/productID/1718/groupID/11/categoryID/152/v/

For your secondary light, get something like this: http://www.cateye.com/uk/product_detail/98
the Cateye HL-EL400. Not very bright but good for being seen and it runs for a long time.