NITECORE Power – The D4 and D2 Digi chargers and NITECORE's li-ion cells

subwoofer

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Author's Statement for Transparency and Disclosure
The test sample/s featured in this article were provided for technical testing and review by "NITECORE". Test samples are retained by the reviewer following publication of the completed review for the purposes of long term testing and product comparisons.
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NITECORE were one of the first (if not the first) manufacturers to offer a serious automatic multi-chemistry battery charger with their release of the i4. Early teething problems were sorted with the i4 V2, and building on this early experience, NITECORE have just released two new 'smart' multi-chemistry chargers, each with a full informative display, the Digi charger D4 and D2.

02-NITECORED4andD2.jpg



NITECORE also offer a range of top specification li-ion cells (but no NiMh option at this time). You can go with a single brand solution, with light, cells and charger all being NITECORE, or mix and match any of these components with other manufacturers products.

01-NITECORECells.jpg



This review is intended to show these products and how they work from a user's perspective with key observations but not including detailed technical analysis.


Author's note: due to the general tendency for reviews to become ever longer, this review is presented in a different format to my previous ones, with all but a few images being animated to attempt to reduce excessive scrolling. You may need to wait for the images to load fully.



Taking a more detailed look:

Starting with the smaller of the two Digi chargers, the D2.

The photos here show; the packaging, contents, the banner label and screen's protective films being removed, the pristine D2, the screen when powered on but no cells are inserted, a single 18650 showing the voltage, then charging current, adding a second li-ion cell shows its voltage, the finished charging voltage displayed for a NiMh cell (also showing the LOW charge current setting), and the display when all cells being charged have completed.

D2overview.gif



A quick look round all sides of the D2.

D2allsides.gif



Now moving onto the larger of the two Digi chargers, the D4.

The photos here show; the packaging, contents, the banner label and screen's protective films being removed, the pristine D4, the screen when powered on but no cells are inserted, a mixture of cell sizes and types showing the voltage, then charging current, using only two bays gives the maximum 750mA charge current, inserting a NiMh cell in the wrong way round shows the 'Err' error condition, the finished charging voltage displayed for a li-ion cell, the manually selectable LiFePO4 charging mode, and the display when all cells being charged have completed.


D4overview.gif



A quick look round all sides of the D4.

D4allsides.gif



The new Digi chargers are slightly bulkier and heavier than the earlier Intellichargers. The D4 and D2 are shown here with an i4

31-D2andD4withi4.jpg




Modes, Features and User Interface:

Both the D4 and D2 operate in exactly the same way, with the only differences being the number of bays and charging currents, so for the purposes of this section I will discuss the D4. Rather than simply repeat everything in the user manuals, I will stick to the salient points. For a look at the full user manuals, you can find them on NITECORE's website:

NITECORE D4 User Manual - NITECORE D2 User Manual

Firstly, the D4 and D2 support a vast array of cells which include:

Li-ion (including IMR) - 26650, 22650, 18650, 17670, 18490, 17500, 18350, 16340(RCR123), 14500 and 10440
Ni-MH and Ni-Cd - AA, AAA, AAAA and C
3V Li-ion / LiFePO4 – (in whichever of these sizes you can find) 26650, 22650, 18650, 17670, 18490, 17500, 18350, 16340(RCR123), 14500 and 10440

Of all of these, the only cells requiring any user intervention are LiFePO4 (all sizes), AAAs (if less than 4 are being charged), 10440s, and some 16430s.

All of the other cell types and sizes can simply be slotted straight in and charge perfectly in any combination.

These chargers have a very simply two button interface with a 'SLOT' button for selecting which bay the display shows detailed information for, and 'MODE' for cycling the display detail and activating a couple of special modes.


For the 'special' cells that need user intervention, it is simply a matter of selecting the LiFePO4 charging mode, or the 'Low' charge current for each bay when you load the cell.

LiFePO4 charging is selected once the cell is inserted by pressing and holding the 'MODE' button for more than 2s immediately after the initial check has completed. LiFePO4 will be shown on the display for that bay to confirm this mode has been selected.

'Low' charging current can be selected at any time, by first choosing the bay with the 'SLOT' button and then holding the 'MODE' button for more than 1s. 'Low' will be shown on the display to confirm this low charging current has been selected. This will use half the maximum charging current (so 375mA in the D4 and 300mA in the D2).


Both units display voltage and current readings. The voltmeter has a maximum reading of 4.20V, and will not display a higher voltage even if a cell slightly over this voltage is inserted. In practice, though I would prefer not to have this limit for peace of mind, but as the Digi chargers terminate li-ion cells at exactly 4.20V, as long as the cell is charged on the D4 or D2, this will show the real cell voltage. In all examples of testing, the reading on the D4 and D2 exactly matched four voltmeters I have to 0.01V.

I've not confirmed the current readings displayed, but have observed the charging current reducing once the charger enters the CV phase of the charging algorithm.

As well as the charging current and cell voltage, the total charging time is also shown and during normal charging these cycle through one after the other.

Both displays are backlit making them easy to see in daylight and quite bright when the room is dark. NITECORE have included the option to switch off the backlight, and this is done by simply pressing and holding the 'SLOT' button at any time for over 1s. Repeating this procedure switches the backlight back on. When the backlight is off, the LCD display is still visible and you can read the values using ambient light.

To get the maximum charging current with the D4 you need to use bay 1 only with bays 2 or 3, and NOT bay 4. The D4 will halve the charging current if you use bays 1 & 4 together, or 2 & 3. NITECORE say this is a design feature relating to charging larger size cells (however I'm not sure I agree).


When inserting a cell, the D4 and D2 carry out a brief cell type and condition test. If this fails for any reason, 'Err' is shown in the display which tells you to remove the cell as soon as you can.

For more details, please see the links at the start of this section for the full instruction manuals.

30-D2andD4nofilm.jpg




Wrapping-up

Since the D4 and D2 arrived, I have used them exclusively for all of my 'considerable' charging requirements. Though not the fastest chargers, so far, they have performed flawlessly. Li-ions come off the charger at exactly 4.20V (depending on the cell age, after resting this might drop off slightly), and NiMh cells at the same voltage my dedicated NiMh chargers give (between 1.47V and 1.54V depending on the exact cell used).

The ability to safely charge single smaller cells is also a boon. I have little use for 10440, but do want to charge a single cell from time to time, and likewise don't always want to charge AAAs at 750mA, so being able to drop to 375mA or 250mA is very useful.

If plugged in, but no cells are inserted, the D4 and D2 also go into an ECO mode, switching off the display and entering a standby mode to save power.

The contact sliders are amongst the smoothest I've found on any charger, but despite this I still prefer to adjust them as much as possible by hand first and then pop the cell into place.

Both units have a 12V socket to use with a car charger adapter. It is a pity NITECORE does not include one with the charger, instead you need to buy it as an accessory. However the socket is a pretty standard size so, like me, you might already have a suitable car adapter (such as the one from the i4).


NITECORE's selection of li-ion cells covers most of your needs. All of them are my preferred cell design, having button tops. Using button tops makes them more universally compatible with different lights. Many lights have built-in physical reverse polarity protection, this protection makes the use of flat top cells impossible.

Though not specifically run through capacity tests, all of the NITECORE cells have performed in accordance with their state capacity in comparative real world use.

The D4 and D2 make it a little difficult to say much more as they….. just….. work.

So in a He-Man stylee , 'By the power of NITECORE, I have the POWER!'

37-D2D4pluscells.jpg


If you enjoyed the review, please remember to 'Like' me on Facebook

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Important update - 26650 Users take note!

The D2 comfortably takes 2x 26650, however, the D4 does not. In the D4 a single 26650 sits very comfortably in either slot 2 or 3, however you cannot fit a 26650 into both slot 2 and 3 at the same time. Slots 1 and 4 in the D4 just about take a 26650, but the cell can easily pop off the positive contact pad and stop charging.
 
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subwoofer

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Reserved for updates...

Important update - 26650 Users take note!

The D2 comfortably takes 2x 26650, however, the D4 does not. In the D4 a single 26650 sits very comfortably in either slot 2 or 3, however you cannot fit a 26650 into both slot 2 and 3 at the same time. Slots 1 and 4 in the D4 just about take a 26650, but the cell can easily pop off the positive contact pad and stop charging.

Update 18 Nov 2014:
Finally some LiFePO4 cells I ordered have arrived so I could try out the LiFePO4 charging.
All four cells terminated at 3.7V and the display held this voltage stead post termination. After 24 hours rest, all four cells are at 3.35V. If anything changes after further use I'll post an update.
 
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Milo Fisher

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I have a D2 and was interested in the trickle issue raised in HKJ's excellent review of the i4 charger at http://www.candlepowerforums.com/vb...ew-of-Charger-NiteCore-Intellicharger-i4-2014. I charged up a partially discharged 1600 mAh Panasonic NiMH battery and was pleased to see the 500 mA output was exactly that as measured on my multimeter.

P9014882_zpsa5058ac6.jpg


After it finished charging, there was no trickle current (compared to 100 mA as measured by HKJ).

P9014884_zps5f161491.jpg


I am pleased to see that they have removed the trickle charge feature and am very happy with the D2 charger.
 

pilou

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A couple of comments on the great review:

- Just a minor correction: the low current mode on the D2 runs at 300mA, not 250mA (at least on mine).
- A number of vendors are bundling the car charger cable in very cost effective packages.

I have so far charged two 18650s and a bunch of AA Eneloops. The Eneloops actually charge faster and with less heat than the simple charger Sanyo bundles with their multi-battery packs. Being able to charge LifePO4 batteries is a great feature since a I am planning on getting a few of them for my single CR123 cell lights.

D2 vs D4: When I ordered my D2 a couple of weeks ago, the nearly double cost of the D4 did not make sense to me. Sure, you get higher charging current capacity, but not when charging four batteries at the same time, in which case you actually end up with lower charging current. So for people whose main priority is to charge many batteries as quickly as possible, buying two D2s instead of a D4 would have made more sense. Also, the spacing between the bays is much more generous on the D2, making it a lot easier to remove batteries.

But I now see that you can get a D4 bundle for $US28 compared to $20 for the D2. The price difference now makes a lot more sense. At those prices they are both good values.
 
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twin63

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Very informative review. Thanks for posting it. I am new to rechargeables. I purchased a D4 and have used it so far to charge Eneloops, a couple of 18650's, and a couple of 14500's. I have a question, though. I just bought a used Quark Pro QP2L-x. I will be running the KeepPower 16650 in this light. It's not listed as a cell that the D4 is compatible with. Will I need to buy a new charger for the 16650 cells, or will I be able to charge it on the D4? I will email tech support at Nitecore, but just wondered if anyone has already dealt with this.
 

UnderPar

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Very informative review. Thanks for posting it. I am new to rechargeables. I purchased a D4 and have used it so far to charge Eneloops, a couple of 18650's, and a couple of 14500's. I have a question, though. I just bought a used Quark Pro QP2L-x. I will be running the KeepPower 16650 in this light. It's not listed as a cell that the D4 is compatible with. Will I need to buy a new charger for the 16650 cells, or will I be able to charge it on the D4? I will email tech support at Nitecore, but just wondered if anyone has already dealt with this.

No need. I also have the same question before. But the answer is yes, it can charge your 16650.
 

HKJ

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Very informative review. Thanks for posting it. I am new to rechargeables. I purchased a D4 and have used it so far to charge Eneloops, a couple of 18650's, and a couple of 14500's. I have a question, though. I just bought a used Quark Pro QP2L-x. I will be running the KeepPower 16650 in this light. It's not listed as a cell that the D4 is compatible with. Will I need to buy a new charger for the 16650 cells, or will I be able to charge it on the D4? I will email tech support at Nitecore, but just wondered if anyone has already dealt with this.

There is no problem charging the Keeppower 16650 in the D4.
Generally chargers do never list all the LiIon sizes they support, there are simply to many sizes. Just with the xx650 cell you have: 26650, 18650, 17650, 16650, 14650.
 

pilou

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I will be running the KeepPower 16650 in this light. It's not listed as a cell that the D4 is compatible with. Will I need to buy a new charger for the 16650 cells, or will I be able to charge it on the D4? I will email tech support at Nitecore, but just wondered if anyone has already dealt with this.
Yes, but with a small caveat. A 16650 is supposed to be charged to 4.3V to reach full capacity. But based on some tests (posted on this site among others), they will reach 95+% of full capacity on a regular 4.2V Li-ion chargers, which is good enough for me.
 

HKJ

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Yes, but with a small caveat. A 16650 is supposed to be charged to 4.3V to reach full capacity. But based on some tests (posted on this site among others), they will reach 95+% of full capacity on a regular 4.2V Li-ion chargers, which is good enough for me.

And on the Keeppower the protection prevents charging to 4.3V, making a 4.2V charger perfect for the Keeppower 16650.
 

subwoofer

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A couple of comments on the great review:

- Just a minor correction: the low current mode on the D2 runs at 300mA, not 250mA (at least on mine).
- A number of vendors are bundling the car charger cable in very cost effective packages.

I have so far charged two 18650s and a bunch of AA Eneloops. The Eneloops actually charge faster and with less heat than the simple charger Sanyo bundles with their multi-battery packs. Being able to charge LifePO4 batteries is a great feature since a I am planning on getting a few of them for my single CR123 cell lights.

D2 vs D4: When I ordered my D2 a couple of weeks ago, the nearly double cost of the D4 did not make sense to me. Sure, you get higher charging current capacity, but not when charging four batteries at the same time, in which case you actually end up with lower charging current. So for people whose main priority is to charge many batteries as quickly as possible, buying two D2s instead of a D4 would have made more sense. Also, the spacing between the bays is much more generous on the D2, making it a lot easier to remove batteries.

But I now see that you can get a D4 bundle for $US28 compared to $20 for the D2. The price difference now makes a lot more sense. At those prices they are both good values.

Thanks for your comments, and the correction (missed this due to not getting my normal thread update emails). Yes, of course the LOW on the D2 is 300mA (main review corrected now). I had also added a comment about the bay size and 26650 cell charging. In some ways I would prefer a 4 bay D2 the size of two D2s stuck together.
 

mwb01

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3V Li-ion / LiFePO4 – (in whichever of these sizes you can find) 26650, 22650, 18650, 17670, 18490, 17500, 18350, 16340(RCR123), 14500 and 10440

Thanks for the review!

I'm considering buying the D2 so I can get rid of my gazillion different chargers, and was wondering if the above quotation means it can charge these 3v Li-Ion batteries. I'm guessing they use some kind of circuit to force a regular 3.7v cell down to 3v, since Tenergy says they should only be charged with their special charger. Do you know if the D2 could charge them safely and effectively?

Thanks
 

subwoofer

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Thanks for the review!

I'm considering buying the D2 so I can get rid of my gazillion different chargers, and was wondering if the above quotation means it can charge these 3v Li-Ion batteries. I'm guessing they use some kind of circuit to force a regular 3.7v cell down to 3v, since Tenergy says they should only be charged with their special charger. Do you know if the D2 could charge them safely and effectively?

Thanks

The method used by Tenergy is different to the LiFePO4 chemistry in that (I think) they use a PCB to give 3V output characteristics from a standard 4.2V cell. These cells typically need the cell inside to be charged to 4.2V or they don't store the energy they should. I would suspect that these should be charged as normal li-ions making the LiFePO4 charge mode of the D2 and D4 irrelevant. However, and it is a big HOWEVER, I do not have any of these cells, nor the full understanding of how they work and what can be done safely with them. HKJ might have a better idea than I do, so my advice is to not go jumping in to this without further investigation.
 

pilou

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The method used by Tenergy is different to the LiFePO4 chemistry in that (I think) they use a PCB to give 3V output characteristics from a standard 4.2V cell. These cells typically need the cell inside to be charged to 4.2V or they don't store the energy they should. I would suspect that these should be charged as normal li-ions making the LiFePO4 charge mode of the D2 and D4 irrelevant. However, and it is a big HOWEVER, I do not have any of these cells, nor the full understanding of how they work and what can be done safely with them. HKJ might have a better idea than I do, so my advice is to not go jumping in to this without further investigation.

There are two types of rechargeable Tenergy RCR123s on the market: the one you just described, which is blue and is (over?)rated at 900mAh, and then there is an actual LifePO4 Tenergy that is green and rated at 750mAh. I just bought a few of the green ones and charged them on the D2 on the LifePO4 setting. The terminal charging voltage was 3.70V. The LifePO4s retain their voltage better and therefore probably deliver as much or perhaps even more energy than the 900mAh LI-ion with PCB voltage regulation. In addition, they don't come with the warning of the 900mAh, "Initial cell voltage of 3.6V switches to 3-3.2V within 12ms", they cost 30% less, and they will likely last longer. It's a no-brainer in my view. I have already tried them in a 1-cell Inova T1 and a two-cell X5. At $3 a pop, you can't go wrong with them.

PS: it started with const current and then switched to const voltage near the end with trickling current.
 
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subwoofer

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Update 18 Nov 2014:
Finally some LiFePO4 cells I ordered have arrived so I could try out the LiFePO4 charging.
All four cells terminated at 3.7V and the display held this voltage stead post termination. After 24 hours rest, all four cells are at 3.35V. If anything changes after further use I'll post an update.
 
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