Nitecore d4 and charging rcr123a
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CelticCross74
Flashlight Enthusiast
most 16340's charge to 4.20v. The 3.7v printed on the wrapper is I believe the minimal voltage rating I am sure more will chime in. Your d4 is designed to be able to tell what kind of cell is in each slot d4 "reads" the cell in each slot independently and charges the cells according to its chemical type and voltage capacity. Your d4 is working correctly and will cut off at what its programmed as a "safe" max voltage for each individual cell. Your d4 deemed 4.18v was the safest max voltage for the cell so it cut it off at that point which is fine.
KeepingItLight
Flashlight Enthusiast
Li-ion rechargeable batteries have a wide voltage range during use. Fully charged, most of them measure 4.2 volts. Fully drained, perhaps as low as 2.5 volts or 2.8 volts, although most of the energy is gone by the time you reach 3.0 volts. So the typical operating range is, say, 3.0v to 4.2v.
This puts battery makers in a quandary. How many volts should they say their batteries have? The answer they chose is use the "nominal" voltage, 3.6 or 3.7 volts, which is like an average. That is the number printed on the label. Some makers use 3.6 volts; others, 3.7.
This can be confusing, because there is another kind of lithium battery, the LiFePO2, that has a voltage range between 2.5 and 3.6 volts. Fully charged, they have 3.6 volts. Their nominal voltage, however, is only 3.2 volts. This latter number is the one printed on the label.
Yet a third kind of Li-ion battery exists. It is similar to the 4.2-volt batteries, except it can be charged higher. It is fully charged at 4.35 volts. Its nominal voltage is usually given as 3.7 or 3.8 volts.
There is also a confusion as to exactly what voltage an RCR123 battery has. Some companies use that designation for 3.7-volt batteries that can be charged up to 4.2 volts. Other companies reserve that name for 3.2-volt LiFePO2 batteries that can be charged to a maximum of 3.6 volts. See the article CR123A and rechargeable substitutes by HKJ for more information about this.
The bottom line is that you have to know what kind of battery your device will accept, and learn how to properly charge it.
This puts battery makers in a quandary. How many volts should they say their batteries have? The answer they chose is use the "nominal" voltage, 3.6 or 3.7 volts, which is like an average. That is the number printed on the label. Some makers use 3.6 volts; others, 3.7.
This can be confusing, because there is another kind of lithium battery, the LiFePO2, that has a voltage range between 2.5 and 3.6 volts. Fully charged, they have 3.6 volts. Their nominal voltage, however, is only 3.2 volts. This latter number is the one printed on the label.
Yet a third kind of Li-ion battery exists. It is similar to the 4.2-volt batteries, except it can be charged higher. It is fully charged at 4.35 volts. Its nominal voltage is usually given as 3.7 or 3.8 volts.
There is also a confusion as to exactly what voltage an RCR123 battery has. Some companies use that designation for 3.7-volt batteries that can be charged up to 4.2 volts. Other companies reserve that name for 3.2-volt LiFePO2 batteries that can be charged to a maximum of 3.6 volts. See the article CR123A and rechargeable substitutes by HKJ for more information about this.
The bottom line is that you have to know what kind of battery your device will accept, and learn how to properly charge it.
CelticCross74
Flashlight Enthusiast
thanks KIL was having a senior moment about the label ratings. OP what light are you putting the cell in? Is it just one cell or 2?
Thanks guys, good to know there is nothing wrong with my charger and instead just confusion on my part.
CelticCross74: it is a Nitecore branded rcr123a going in a s1 baton. I've never used 2 x rcr123a since I just use 18650s instead for lights with that that set up.
CelticCross74: it is a Nitecore branded rcr123a going in a s1 baton. I've never used 2 x rcr123a since I just use 18650s instead for lights with that that set up.
@KeepingItLight: Thanks for the info! I was always confused by the label vs the final charged voltage as displayed on the charger. I guess this stuff also applies to like Eneloops as well? It seems to stop charging at ~1.5V but seems to settle down to ~1.4V or so...
KeepingItLight
Flashlight Enthusiast
Right. I often see NiMH described as a 1.2 volt battery. Most of the energy is gone by the time you reach 1.0 volts. Many devices won't go that low; they stop working around 1.1 volts. Most chargers take them over 1.5 volts, but the voltage quickly settles to something over 1.4 volts when you take the batteries off the charger.
When it comes off the charger it's fully charged.
Yet things aren't necessarily finished.
Many prefer to keep a spare set pre-charged so that the voltage is settled into it's best, most efficient output level.
If you have a chance take your batteries off the charger and let 'em set over night try it. Put 'em back the next day and note the difference. Your cells didn't lose a lot of power over night but have "settled" like cereal does in it's box.
I let mine settle for 45 minutes or so before using them.
Yet things aren't necessarily finished.
Many prefer to keep a spare set pre-charged so that the voltage is settled into it's best, most efficient output level.
If you have a chance take your batteries off the charger and let 'em set over night try it. Put 'em back the next day and note the difference. Your cells didn't lose a lot of power over night but have "settled" like cereal does in it's box.
I let mine settle for 45 minutes or so before using them.
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Parrot Quack
Flashlight Enthusiast
When it says "ALL," it's done.
vadimax
Flashlight Enthusiast
I suppose, 3.6V indication for Li-Ion batteries is their optimal storage voltage (some 40% discharge), so, when anyone buys it he observes exact correspondence with the marking on a package. Seems logical -- to avoid any problems with clients, having no idea about the chemistry 
