OK, So I have this Elektrolumens EDC MCE light that I have had for awhile. I have run some ultrafire Gray 18650’s rated at 2400mAh in it for about 3 years (I have only fully discharged the batteries maybe a dozen or so times each). I have recently been bit by the flashlight bug and have started getting more into it. So anyway, I bought some new trustfire 3000mAh batteries for it and just decided to do some comparisons with tail cap readings as since I can’t directly compare the batteries side by side in identical flashlights and here are my readings.
All 4 batteries fresh off the charger give a volt reading of 4.08 to 4.10 VDC
The ultrafire grays 2400mAh give tail cap current readings of
1.5A & 1.7A
The trustfire 3000mAh give tail cap readings of
2.4A & 2.6A
All reading were taken with a fluke meter (rather high quality) and given about 5 seconds to level out. I thought that the mAh only really applied to the run time on the light as long as they were supplying enough current to drive it. Do these readings mean that the light is quite a bit brighter with the trust fires? I mean the difference between the 2 types of batteries is as great as 50%, is that normal?
I believe that the light is a direct drive light if that helps.
Also, I have a Tank 007-703 with about 4 10440’s that I use in it. One of them seems to be dying WAAAYY faster than the others but I keep getting them mixed up. Is there a way I can tell which battery is the bad one without waiting an hour plus to see the light die? Any help on these questions would be greatly appreciated. Thanks in advance for your input and time.
Ottis
It looks like those grey trustfires are getting fatigued/old - 4.08 fresh off a charger most likely means the battery has built up some internal resistance due to use/age and could explain why you are seeing lower currents vs the trustfire 3000s. Do the trustfire 3000s come off the charger with higher voltage? 4.17-4.20 would be considered a full charge for most new li-ion batteries. (there are a select few that go to 4.35, but all trustfires i have seen are 4.2 li-ion) I personally recycle my batteries when they wont charge past 4.1v anymore.
As far as testing which battery is “bad” you could run a capacity test if you have a hobby charger and that would tell you which cells are performing best.
I believe you could also try testing internal resistance in ohms of each cell with your multimeter - I personally have not done this and will step aside on this one so that a more experienced forum member can chime in
Hope some of this helps, I am sure some other members will help me out here too
Cheap batteries will give you low current readings. They just can’t provide the current of a quality cell. Those grey’s look like they ready to be tossed as stated above. Quality cells will more than likely give you even higher tail cap readings than the 3000’s. I wouldn’t be surprised with a Panasonic cell or sanyo that if you don’t get a reading of 2.8amps.
The trust fires came off in the same 4.08 to 4.11 range. Is there a possibility that my charger is screwy? I have another charger here at work I will have to take home and try. I just ordered Panasonis 3400mAh from amazon. I will try those soon.
It could be possibly. Wait until you get the Panasonics and check those immediately of the charger. The charger seems to terminate early which you will actually get longer cell life with it and only shortens the total capacity by a small percentage. What charger do you have?
Total capacity is a minor difference, yes, but the big hit comes from the low voltage which self-limits the current it can provide. Single cell lights and Vf and all that. Two identical purple Samsung ICR 2800s, one charged to only 4.20v and one fully charged to 4.30v, the higher voltage one will push half an amp more into a direct drive XML2.
I am at work. I will have to look at the charger when I get home to see make/model. I also have a charger here at work that I am going to take home and see what it does to the voltage in the cells.
Correct you are, but from his current readings I doubt his running direct drive. Difference only being a few minutes if not less than a minute at high current draw. Depends alot on led vf and battery used and the particular current draw with or with out regulation. http://lygte-info.dk/info/BatteryChargePercent%20UK.html
Update: Well, with what little info I can find, maybe this light is direct drive with a resistor. :~
If you want the full performance of the light you will need to charge the cells fully.
With a driver it'll be even more sensitive to cells that can't maintain high enough voltage under load because of losses in the driver. Voltage has to be higher than the Vf at whatever desired current plus driver losses.
I am still new to this hobby, so I am trying to learn. I am not sure what drivers do or what VF is. I have a limited amount of electronics training from 21 years ago, so once I do more research I am sure that I can grasp it.
Thanks for your help
Ottis
Vf is shorthand for 'forward voltage'. The higher the voltage you apply across an LED, the more current will flow. It works like a tap handle on a water faucet. More voltage opens the valve further. Different types of LED have different voltage:current curves.
If the voltage is limited to 3.0v, no more than around 1 amp will pass through the LED. 3.6 volts will give about 4 amps. If the cell can't maintain 3.6 volts under load, it'll never be able to reach 4 amps.
That's why the starting voltage has such a big impact - a partially charged cell at 4.08v is handicapped from the start, not only is the voltage lower but the partial charge means the voltage will sag under load more than a truly fully charged cell. The lower the voltage, the less current will flow and the less light that will come out the shiny end.
I apologize comfychair, didn’t realize this was a direct drive light until I did a little more research. The current readings fooled me, I would have expected the fires to give a little more current than that.
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dohcsvt, That’s I guess is where I came up with the resistor then, xml. So if there is no resistor and its direct drive, you will get the most output with a cell that gives the most current under a load, like a IMR cell. The run time will be reduced as most 18650’s IMR’s will only have about 2250mah or less but hold there voltage very well and will give the most lumens through out the run time. You could possible see 5amps or more when measured and 850 lumens. With the current your drawing now (2.4amps) around 620 lumens. The Panasonics 3100 or 3400mah will give you good over all performance with a lot better performance than your seeing with the fire’s. Should increase run time and the lumens output. Wouldn’t be surprised if you see way more than the 2.8amps of current draw I first quoted you, possibly 4amps. :bigsmile:
Interesting Info for your light and current draw: http://www.cpfmarketplace.com/mp/showthread.php?200036-EDC-MCE-CNC-Machined-Beautiful-Black-Anodized&p=2437402&viewfull=1#post2437402
Nah I didn't know anything about the light either, just that the numbers it'll do DD with a particular cell & LED is good info for the max it will do with a constant current driver. No point in a 5 amp driver if the cell+LED alone will only do 4 amps.
Ya but the current there showing in this thread was little more like what I was expecting with DD, I guess the charged voltage was holding it back. My initially thought, amc7135 2800mah driver with his reported numbers in the OP.
Holy Crap! From the numbers that are quoted in the other thread I am really down on my current. I have my other charger from work in my lunch bag to go home. I will perform some top off charging whil I watch the news and see what happens with my voltages and henceforth my current readings. I really appreciate all you guys help and explanation on this. I am just trying to educate myself as best I can. I am about to order an Ultrafire C8 with a CREE XM-L2-U3 and I hope to try and drive it hard with some mods. I have to start researcing that. I will report back after the other charger.
so I tried the other charger and here are the results
Trust fire
4.20 VDC 2.96A
4.21 VDC 2.98A
Ultrafire
4.10VDC 1.87A
4.12VDC 1.89A
My readings still seem low, but that is what I got. The charger that charged them more has no name or model # on it. The one that did poorly is made by DSD. Do you guys have a recommendation for a reasonably priced good charger that will do 18650, 14500 & 10440. That is the type of charger that does not do so well. The better charger that I have only does 18650. Thanks for your help.
Ottis
I think you need better cells more than you need a better charger. A lot of cheap chargers will do OK, but have quirks like the light turns green loooong before the charge cycle is actually completed, and it needs sometimes another hour before the cells are fully charged. Though if you buy some quality cells you might as well get a quality charger at the same time.
The Nitecore i4 V2 seems to be well liked around here and does follow the correct charging algorithm for a li-ion. It will also charge Nimh. Here’s HKJ’s review.
