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Post by humanshield on Oct 28, 2016 11:57:39 GMT -5
I have a LED camping lantern that uses 4, D cell Alkaline batteries but I want to create a rechargeable battery pack for it.
About the closest thing I've found without going under voltage that will fit inside the compartment seems to be 3.7v, 18650 batteries.
But doing the math, 1.5v x 4 = 6 volts and 3.7v x 2 = 7.4 volts
So I'll be over voltage by 1.4 volts. I'm somewhat confident that that 1.4v over won't do any harm...but not positive.
I could also use 5, 1.2v cells to get 6 volts....which might be a better idea but getting 5 batteries to fit neatly inside the existing battery compartment probably won't fly.
Maybe 4 rechargeable 1.2v D cells would work but I'm concerned the lower voltage might make the lantern shut off prematurely when it detects the lower voltage.
Just wondering if anyone else messes around with LED lighting and or subbing non rechargeable power for rechargeable power in things like this LED lantern.
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Post by Deleted on Oct 28, 2016 13:20:24 GMT -5
Why not run it from a single "dead" D cell battery like this?: www.youtube.com/watch?v=GMftETOpLxMI would not add the red lens if it were for me, but my friend wanted that to preserve his night vision. He is in the Navy. Last I heard from him, this light was still working out well. I originally used this with an AA battery but he wanted longer running hours so I went with the D. Bill |
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Post by humanshield on Oct 28, 2016 14:37:07 GMT -5
Why not run it from a single "dead" D cell battery like this?: www.youtube.com/watch?v=GMftETOpLxMI would not add the red lens if it were for me, but my friend wanted that to preserve his night vision. He is in the Navy. Last I heard from him, this light was still working out well. I originally used this with an AA battery but he wanted longer running hours so I went with the D. Bill Yes no need for a red lens |
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Post by humanshield on Oct 28, 2016 14:43:01 GMT -5
I'm afraid it went over my head partner.
The purpose of buying this lamp is because it has several brightness settings ranging from 750 lumens to 450 lumens to 250 lumens to 150 lumens.
Sometimes I might want to use the 750 lumens. In the Youtube example you changed the bulb....I don't really want to do that.
Would this Joule Thief thing still work?
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Post by Deleted on Oct 28, 2016 15:34:41 GMT -5
I'm afraid it went over my head partner. The purpose of buying this lamp is because it has several brightness settings ranging from 750 lumens to 450 lumens to 250 lumens to 150 lumens. Sometimes I might want to use the 750 lumens. In the Youtube example you changed the bulb....I don't really want to do that. Would this Joule Thief thing still work? I think the bulb and circuit in the video had 2 settings of about 350 and 600 lumens, or thereabouts. It just had a high and low setting and I can't remember if I added more resistance to that part of the circuit or not...I'll have to go back and watch it again as it was about 3 years ago or so when I did that. A Joule Thief can certainly help you, the issue is matching the circuit to the bulb for the application. That circuit in my video outputs about 350-400 volts at around a 50% duty cycle (it is off half the time) at around 30,000 times per second freq. This really helps you get a good amount of light for a much longer time because your eyes can not tell when it is off but it is off half the time so, theoretically, you can double (not quite in the real world) your run time for the same amount of light output from the same amount of input energy. What type of bulb is in the lamp in its stock form? This one I modded had a floro tube and would only run on high from 4 D batteries for like an hour. Now, it will run over 12 hours from a single D cell on high, and a lot longer on low. Bill |
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Post by humanshield on Oct 28, 2016 15:47:52 GMT -5
My lantern has a C.O.B LED setup
Just wondering...how would a JT circuit work with rechargeable batteries?
I plan to set the lamp up on a pole and leave it on all night because where I go camping is really dark and isolated and I like to see critters sneaking up on me.
I was out there last weekend and some wild dogs came around at 3am. Woke me up bumping around outside.
I see deer, armadillos, snakes, raccoons, wabbits, dogs and I swear I once saw Big Foot...but maybe it was the beers after all.
Anyway, it's usually so dark that probably 250 lumens would light up a pretty good area.
So 250 lumens for 10 hours I'd say.
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Post by Deleted on Oct 28, 2016 15:50:02 GMT -5
My lantern has a C.O.B LED setup Set up to run at 6 volts? Is this correct? Bill |
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Post by humanshield on Oct 28, 2016 15:53:56 GMT -5
My lantern has a C.O.B LED setup Set up to run at 6 volts? Is this correct? Bill Exactly...4 D cells |
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Post by humanshield on Oct 28, 2016 15:56:54 GMT -5
I'm afraid it went over my head partner. The purpose of buying this lamp is because it has several brightness settings ranging from 750 lumens to 450 lumens to 250 lumens to 150 lumens. Sometimes I might want to use the 750 lumens. In the Youtube example you changed the bulb....I don't really want to do that. Would this Joule Thief thing still work? I think the bulb and circuit in the video had 2 settings of about 350 and 600 lumens, or thereabouts. It just had a high and low setting and I can't remember if I added more resistance to that part of the circuit or not...I'll have to go back and watch it again as it was about 3 years ago or so when I did that. A Joule Thief can certainly help you, the issue is matching the circuit to the bulb for the application. That circuit in my video outputs about 350-400 volts at around a 50% duty cycle (it is off half the time) at around 30,000 times per second freq. This really helps you get a good amount of light for a much longer time because your eyes can not tell when it is off but it is off half the time so, theoretically, you can double (not quite in the real world) your run time for the same amount of light output from the same amount of input energy. What type of bulb is in the lamp in its stock form? This one I modded had a floro tube and would only run on high from 4 D batteries for like an hour. Now, it will run over 12 hours from a single D cell on high, and a lot longer on low. Bill That is absolutely incredible! One hour on 4 D cells, but 12 hours on ONE D cell with the JT circuit. Of course, the batteries are truly exhausted after that. Can't use rechargeables? |
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Post by Deleted on Oct 28, 2016 17:23:36 GMT -5
You can use rechargeables but, 2 things, first, this circuit will drain them totally and, you never want to do that with any type of rechargeable battery so, you would have to monitor that closely. Second, since that type of battery is only 1.2 volts fully charged, you would be looking at 4 x 1.2 or 4.8 volts as opposed to 6. If you go the 18650 route, (I use those all the time and have about 15 of them lying around or in different devices) you could use 2 of them and have about 7+ volts.
Do we have any idea of the amp/milliamp draw on your bulb at 6 volts? If it is not too high, I may have a good idea for a nice circuit that is premade and can be used to output 5.5 volts with a 1.5 volt input.
Bill
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Post by Deleted on Oct 28, 2016 17:34:41 GMT -5
www.sparkfun.com/products/10968This board here is using the NCP 1402 chip (surface mount) and the price is great considering I can not even solder that tiny, tiny chip and supply the other components for this price. I bought several of the 3.3 volt units but this board takes any input from about 1 volt and supplies 5 volts. It can only handle 200 mAs though so your bulb may draw a bit more than that. But, if not, this is a great chip and is sort of a JT circuit built into a chip. Bill PS Electronics is just one of my hobbies and I have only really been into it for about 8 years or so. I am trained in engineering and machining but this is something I have always wanted to learn about.
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Post by eclark5483 on Oct 28, 2016 17:34:57 GMT -5
How about just buying a 7.4 volt bulb?
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Post by Deleted on Oct 28, 2016 22:48:35 GMT -5
How about just buying a 7.4 volt bulb? I don't know if they actually make one of those and..one could just add the right value resistor and all would be good. The JT circuit is good because it allows a lot of visible light for a longer time from the same amount of input. It is sort of a trick but...remember we use ac lights in our homes that turn on/off 60 times/second and we can't tell right? So, if you use a circuit that does this 30,000 times/sec. and uses half the energy and can last twice as long...why not? Bill |
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Post by FrankenMech on Oct 29, 2016 0:09:09 GMT -5
Fewer on-off switching operations will also save power. The transition from on to off or the reverse wastes energy while switching. The lowest frequency and shortest ON time will provide the most energy savings.
Hook up a variable power supply and a current meter to see what your lamp requires.
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Post by humanshield on Oct 29, 2016 8:39:13 GMT -5
Fewer on-off switching operations will also save power. The transition from on to off or the reverse wastes energy while switching. The lowest frequency and shortest ON time will provide the most energy savings. Hook up a variable power supply and a current meter to see what your lamp requires. From what I read about JT circuits, they are specially made so that there is almost no energy loss during the on/off switching. Counter intuitive...but somehow it seems to work. |
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