Question about battery pack on a chea....inexpensive Amazon light!!

mikekoz

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I just received a budget light off Amazon that advertises 5000 lumens and a XHP 70.3 emitter\LED. The instructions say it is powered by 2 26650 cells, but it came with a battery pack that has 2 26650 cells wrapped up, one on top of the other. So it looks like a long 26650! The battery is rated at 3.7v 10000 mAh. This is 2 26650 batteries connected in parallel which I find kind of odd. I would have thought they would have been connected in series where it becomes a 7.2v 5000 mAh battery pack. I am going to assume that if I actually do put 2 separate 26650 cells in this thing, it is going to burn out the emitter or the driver board, correct?? The instructions that came with the light are vague, and just say it will run on 2 26650's or 2 18650's.
 

vicv

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It’s much cheaper/easier to charge cells in parallel. You’ll need to use a multimeter to confirm the electrical orientation
 

mikekoz

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The pack this light came in has 2 26650's in parallel. I confirmed it using a tester. Once fully charged, it is 4.20v. If I put 2 separate 26650's in this light, they will be in series, and will put 7.2v into the light. I guess I do not know enough about flashlight LED voltage tolerances. If the driver in this light was only designed to handle 4.2v, putting 2 separate 26650's in it will damage it. I looked up the Cree XHP 7.3 specs on their web page, and they show it can handle 6v or 12v. This is the problem with buying lights like this as there is not a real company making it that I can see. Finding out what the max voltage the driver will take in it may be impossible. There are several lights on Amazon just like this under different names. Most sell for 30-45.00. The one I got was only about $14.00, so if I cannot figure this out, I will just leave it as it is. I could try and see what happens if I use 2 cells. If it does damage the light, I can get Amazon to replace it, only because the instructions on the box state it will run on 2 26650 or 18650 cells. It does not state one has to use the pack that came with it.
 

vicv

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I’m surprised they sell a light that cheap that not only comes with a proprietary battery, has built in charging, but also a boost/buck circuit that can put out that much current. I don’t even see how’s that’s possible
 

roostre

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On the right side of the Amazon listing for this light, click on "DONLYN" where it states "Sold by DONLYN" which is just beneath "Ships from Amazon".

On the right side of the page which appears after you click on "DONLYN" you can click on "Ask a question" where it states "Have a question for DONLYN?".

Please let us know how they answer your questions and if you are satisfied owning this light.
 

roostre

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The light includes "built-in charging" and "battery state of charge indicator lights" so if you decide to contact the "DONLYN" seller with questions, it would be interesting to know if these functions operate correctly with either "two batteries in parallel" or "two batteries in series" (which would have twice the voltage). It would also be helpful to know if the light itself (or included battery pack) has built-in "Low Voltage Protection" for both "parallel" and "series" battery configurations (or either configuration).

I imagine it would be possible (based on the initial battery configuration's voltage) for "battery charging", "battery state of charge indicators" and "Low Voltage Protection" algorithms to function with a "parallel" or "series" battery configuration, but I also imagine it would be dangerous to rely on the algorithm to always function correctly for all unforeseen circumstances and you should never charge Li-ion batteries in "series".

The "DONLYN" seller offers only three products on their Amazon storefront and all are inexpensive flashlights, so hopefully they know something about their products, but maybe not.

Fortunately during this time of year, because of the holiday shopping season, AmazonUS extends their return window thru January 31, 2022 (instead of the normal 30 day period) which provides more time to contact the seller and do your own testing to ensure the light operates correctly.
 
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mikekoz

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Thank you all for the information! I actually did not realize you should never charge Lithium Ion cells that are in series. The two 26650's I charged I did so on my Nitecore D4 charger. I did send a message to Donlyn and will see what they say. I actually like the light! I am not sure if it is 5000 lumens, but I did not think that claim was overly exaggerated like a lot of the other sellers offering the same light and claiming 90000! All I can say after a few quick tests is that I believe it is well over 1000 lumens. It is kind of hard for me to compare these zoomable lights brightness with one with a standard reflector, but on a white wall test, it blew away a light I have that is rated at 1000 lumens. I am not really a fan of zoomable lights, but this one does a decent job with it. So far it is very much worth what I paid for it. The finish on it is pretty nice and the handle is nice and grippy. It also has a good weight to it. Also, you cannot beat Amazon's return policy! I am going to fully test it when we visit my wife's parents next week. They live out in the country and it is the perfect place to test lights!!
 

roostre

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Technically, it would have been more accurate if I had stated "never charge Li-ion battery cells in series without using circuitry specifically designed for this purpose" since there is a technique known as "balance charging" that can safely charge Li-ion battery cells in series, but it also requires additional electrical connections to each battery cell (or to any groups of cells configured in parallel that are then connected in series) for this special circuitry to operate.

Since we are not sure what would occur if the light's built-in charger was used with two separate battery cells (instead of the included battery pack with two cells in parallel), if you need to replace the included battery pack in the future, you could always safely just use only one battery and purchase or fabricate a "dummy cell with electric continuity" to fill the empty space in the battery tube but then you would also only have approximately half the runtime compared to the included battery pack with two cells.
 

mikekoz

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I am still curious to see if the light will take 7.2v. If so, I have spare cells for it. It may also be brighter with 2 batteries in it, but runtime may not be quite as good.
 

DIWdiver

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I wonder if it can run with cells either in series or in parallel, but can only charge in parallel. That's the only way I can make sense of the fact that their pack is 3.7V, but you can put two of your own cells in the light.

Also, I very much doubt it puts out anything close to 5000 lm. According to the XHP70.3 datasheet, even the highest bin cannot do that at the maximum rated current, and for that price there's no way you got the top bin. Heck, you'd be lucky if you even got a genuine part.
 

mikekoz

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I wonder if it can run with cells either in series or in parallel, but can only charge in parallel. That's the only way I can make sense of the fact that their pack is 3.7V, but you can put two of your own cells in the light.

Also, I very much doubt it puts out anything close to 5000 lm. According to the XHP70.3 datasheet, even the highest bin cannot do that at the maximum rated current, and for that price there's no way you got the top bin. Heck, you'd be lucky if you even got a genuine part.
I have thought the same thing about the LED that it may not actually be an actual XHP70.3. I will take a closeup pic of it this eve and post it here. The bezel and plastic optic easily comes off and I will be able to take a nice closeup shot! Somebody with more knowledge than myself should know what it is! Also, I am thinking that the output is around 2000 lumens, but I am guessing.
 

mikekoz

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Well, the seller got back to me, and they must not have understood my question. They just refunded my money! So, in the next few days, I am going to try the light with 2 of my 26650's and see how it goes. If the light get damaged, I will just buy another one! I will keep you all posted! :grin2:
 

mikekoz

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I put 2 of my 26650 cells in the light, and it did not work. The light initially turned on, then off right away. I immediately removed the batteries and put in the original one, and the light works like normal. In a nutshell, to use one of my batteries, I would need to buy a 26650 dummy.
 
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