Charging 16340 w/ built-in charger

I just bought a 16340 (Fenix brand) with a built-in micro-USB charger. Normally, when I charge a 16340 with a proper charger, I just plug my charger into a wall wart without worrying much about the wall wart's output -- whether 1A or 2.4A, I can set the charger to charge at 500mA (say), and I know my cell is charged safely. For safety's sake, I am guessing that the built-in charger for that 16340 does *not* regulate the current draw... or does it? Or, saying my question another way, do I need to plug my cell into a 500mA output, or can I plug my cell into my 2.4A cellphone charger, and depend on the cell's built-in charger to ensure the CC portion doesn't start too high?

I looked and was not able to find this discussion elsewhere on the forum, though I have to imagine it has been discussed. Exact cell I have here: https://www.google.com/search?q=fen...H-2MKHWd2C6sQ9QEIoQEwBw#imgrc=P2dfaAKdAAljmM:

Thanks for any help!

Joe

Joe Talmadge said:

I just bought a 16340 (Fenix brand) with a built-in micro-USB charger. Normally, when I charge a 16340 with a proper charger, I just plug my charger into a wall wart without worrying much about the wall wart's output -- whether 1A or 2.4A, I can set the charger to charge at 500mA (say), and I know my cell is charged safely. For safety's sake, I am guessing that the built-in charger for that 16340 does *not* regulate the current draw... or does it? Or, saying my question another way, do I need to plug my cell into a 500mA output, or can I plug my cell into my 2.4A cellphone charger, and depend on the cell's built-in charger to ensure the CC portion doesn't start too high?

I looked and was not able to find this discussion elsewhere on the forum, though I have to imagine it has been discussed. Exact cell I have here: https://www.google.com/search?q=fen...H-2MKHWd2C6sQ9QEIoQEwBw#imgrc=P2dfaAKdAAljmM:

Thanks for any help!

Joe

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The load/charging algorithm will dictate the current 'sucked' from the wallwart, or USB charging adapter.

Always have a bigger WW than that required by the charger, in this case the charging module on the 16340. I don't know at what rate it charges.

I'm a big user of 16340s and I like to charge them at 250mA, although I went the first two years charging them up at 500mA with my Xtar WP2 II. Probably wasn't the best, but they still have some useful 'moonlight/low' capacity left.

I don't care to explore the integral USB charging cells, but that's just my bias.

Chris

Ah, ok, so you don't think the charger just stupidly takes whatever the wall wart can supply. I felt like that must be the way it works, but wanted to make sure. The battery itself has printed on it "Input: 5V/500mA", which made me wonder if that implication was, I shouldn't hook it up to anything bigger... but it sounds like you're saying I'm misinterpreting that Input specs, and that it's saying that 500mA is what it will pull in

Joe Talmadge said:

\ The battery itself has printed on it "Input: 5V/500mA", which made me wonder if that implication was, I shouldn't hook it up to anything bigger... but it sounds like you're saying I'm misinterpreting that Input specs, and that it's saying that 500mA is what it will pull in

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Agree.

The fenix website data implies the built in charger will provide 0.3A charging current. I suspect the maximum draw from usb source is never more than 0.25A, likely less. Using a more capable source won't hurt your battery, the built in charger limits the current. Just like if you plug your USB converter into the wall, the USB converter does not know if the wall power circuit breaker is limited to 10A, 15A, or something higher.

Exactly what I wanted to hear and see, thanks!. I'm hoping the row "Charging current by charger: 1A" doesn't mean to suggest I shouldn't use my 2.4A wall wart.

ChrisGarrett said:

I don't care to explore the integral USB charging cells, but that's just my bias.

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Honestly I never thought I'd have a use case for them either, I looked at them as a bit gimmicky, more aimed at a casual user. But I've been finding myself often enough out, with no Li Ion charger but always with access to a wall wart and/or my spare portable battery I carry for my phone, and thinking that (especially for a multi-day trip) it sure would be nice to have the capability to re-charge that 16340. So my travel/day-trip light are both getting cells with built-in chargers, we'll see how I like them

Joe Talmadge said:

Exactly what I wanted to hear and see, thanks!. I'm hoping the row "Charging current by charger: 1A" doesn't mean to suggest I shouldn't use my 2.4A wall wart.

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No, that 1A is the maximum charge current if you put the battery into a charger, instead of using the built in charge circuit. I suspect most folks would recommend charging this cell at something less than 1A, the 0.3A used by the internal charge circuit is a good spot to me IMO.

sbslider said:

........The fenix website data implies the built in charger will provide 0.3A charging current. I suspect the maximum draw from usb source is never more than 0.25A, likely less............

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USB power sourced battery chargers are typically a linear regulator and as such the USB 5v current is pretty much the same as the charging current going into the battery. I verified on my Fenix ARB-L16-700U and it was 330mA current from the USB 5v source. Other USB chargers that I have only consume about 5mA to power the electronics so if its a decent linear design, then you can just measure the 5v current (which is way easier to do than trying to measure the battery current) and assume that is about the same as that which the battery is being charged with.

Another confusion that was cleared up by Chris is that the receiving device will only pull the amount of current that it wants. Thus if you use a USB 2.4A cell phone charger, the ARB-L16-700U along with any other lithium ion charger powered by a USB voltage will only draw the current that it was designed to do. 2.4A is just the max capability of that power source. So the most important aspect is to have a voltage source that has at least the current capability for which the charger will pull. In the case of the ARB-L16-700U, any USB source of 400mA or higher will suffice. You could even plug into a USB 2.0 port on a computer .

The only concern that I have with the ARB-L16-700U is that the height is longer. Take a look at the pic on post #17. As long as that isn't a problem with your lights, then I see no issue with using the ARB-L16-700U.
http://www.candlepowerforums.com/vb...range-Black)&p=5176090&highlight=#post5176090

sbslider said:

No, that 1A is the maximum charge current if you put the battery into a charger, instead of using the built in charge circuit. I suspect most folks would recommend charging this cell at something less than 1A, the 0.3A used by the internal charge circuit is a good spot to me IMO.

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Gotcha! .8C is my usual compromise, I realize it's rougher than many people like. It's listed as 700mAh, I figure it's maybe 600mAh in reality, so 500mA hits my .8-ishC. But, self-charging at .3A is great

Joe Talmadge said:

Gotcha! .8C is my usual compromise, I realize it's rougher than many people like. It's listed as 700mAh, I figure it's maybe 600mAh in reality, so 500mA hits my .8-ishC. But, self-charging at .3A is great

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The Fenix 700mAh battery is pretty close to that......no exaggeration on the part of Fenix. with the link I provided, you can see the review by HKJ. That was the regular Fenix 16340. But I see no difference in performance between it and the "U" version. Someone else may chime in if they have a different experience but so far I can't tell a difference in performance.

Personally I would charge at something less than 500mA. I have done 500mA on mine a couple of times but most of the time I will just do 250mA. With the ARB-L16-700U, you are stuck with the 300mA charge rate if using the built in charger, but you can also charge that battery on an external charger too. You don't have to use the built in port if you don't want to. That is the nice thing about that battery for those that might find themselves away from home but have some type of cell phone charger with them.......just another option.

hiuintahs said:

USB power sourced battery chargers are typically a linear regulator and as such the USB 5v current is pretty much the same as the charging current going into the battery. I verified on my Fenix ARB-L16-700U and it was 330mA current from the USB 5v source. Other USB chargers that I have only consume about 5mA to power the electronics so if its a decent linear design, then you can just measure the 5v current (which is way easier to do than trying to measure the battery current) and assume that is about the same as that which the battery is being charged with.

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Thanks for the clarification, did not know that. Makes sense, linear is very simple, so long as the generated heat is not an issue.

hiuintahs said:

Another confusion that was cleared up by Chris is that the receiving device will only pull the amount of current that it wants. Thus if you use a USB 2.4A cell phone charger, the ARB-L16-700U along with any other lithium ion charger powered by a USB voltage will only draw the current that it was designed to do. 2.4A is just the max capability of that power source. So the most important aspect is to have a voltage source that has at least the current capability for which the charger will pull. In the case of the ARB-L16-700U, any USB source of 400mA or higher will suffice. You could even plug into a USB 2.0 port on a computer .

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Well put

sbslider said:

Thanks for the clarification, did not know that. Makes sense, linear is very simple, so long as the generated heat is not an issue......

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Ya, the difference in voltage between USB (5.0v) and the battery termination point (4.20v) is too close to warrant a switching type of regulator. I suppose it can be done with some intricate design, but the amount of room in these flashlights and in the case of a battery just isn't very much space and so its just best to use a small USB to lithium ion charging chip. Also that helps with cost. There are a lot of those IC's on the market and they don't take many other components to go along with them to make a complete charging circuit. They are not bad. Most of the time the current is fairly low and so not so much of a concern for heat and power consumption issues. The biggest amount of power loss will be when the battery is at its lowest voltage. Thus the power loss in the IC is the voltage difference between USB input and battery x the charging current. With a battery at 3.0v that is about 40% loss. Now I could be wrong but I assume they use a single chip for charging. With a 12v input, I utilize switching technology and the efficiency is a lot better. But I have to say if I was to do something with onboard charging port like on a battery or a flashlight, it just makes more sense to utilize the single chip USB route.