Charger NiteCore Intellicharger D2





This charger is based on a i2 with a display added and a couple of improvements. This makes it possible to charger more battery types than the i2 and also follow the charging in more details.



The cardboard box lists lot of specifications, battery types and features.



The box contains the charger, a mains cable, manual and a warranty card.



The charger has two power connectors, one for mains input (100-240VAC 50/60Hz) and one for 12 VDC input.



The charger has two switches:
SLOT: Used to select slot, holding it down will turn the display off or on without affecting the charging.
MODE: Used to change value displayed (Volt, mA, time), with longer presseds it can also be used to select low charge current and LiFePO4.



The charger has a large display with background light.




The display looks good, but is a bit on the technical side. The lower part of the display shows the two charge bays, the upper part shows the status for one bay. The actual bay is selected with the SLOT switch.
The numbers will automatic switch between volt, mA and time, but can also be switched with quick presses on the MODE switch.
Holding the MODE switch for about one second will select "Low", i.e. 300mA charge current.
Holding the MODE switch for about two seconds will select "LiFePO4", i.e. 3.6 volt charging. Releasing the button and pressing again will select low current.
There is a small "Chg. Finished" text on the upper display, this is used on finished channels. When all channels with batteries in are charged the charger will show "ALL" in the numeric display.



The slots uses the usual construction and works well. They can handle batteries from 30mm to 69.3 mm long.
That excludes some of the longest batteries, especially some protected 26650.







The charger can handle 69.3 mm long batteries, inclusive flat top cells.
With C batteries there is a problem with the small button top sliding off the plus pole on the charger.




A look inside the charger

Nitecore asked me to show the inside of the charger:



Four screws has to be removed to get into the charger.



The display uses a long zebra connector between it and the circuit board. The background light is a separate module.



On the circuit board can be seen:
A long isolation slot between the mains and the rest of the circuit.
Mains input has a fuse, NTC, a noise suppression capacitor and uses a IC for controlling the mains switcher.
Safety capacitor between mains and low volt side.
The two inductors marked 101 is for the two charge channels.









Measurements

• Discharges LiIon with 2.2mA and NiMH with 0.16mA when not connected to power
• With a empty battery the charger will try to activate it, then show "Err" after a short time.
• At 0.8 volt the charger will assume NiMH and start charging.
• The charger will assume NiMH below 1.8 volt and LiIon above 1.8 volt.
• Will not restart if battery voltage drops.
• Charges with 0.2mA when LiIon battery is full.
• Voltmeter readout freezes when charging is finished
• Voltmeter is within 0.03 volt above 0.8V.
• Voltmeter has a max. readout of 4.20 volt.
• Current readout is not average charge current.
• Charge will restart charging after power loss or battery insertion.
• The button marked "SLOT" will change the display to the next slot with each press.
• The button marked "MODE" will change value displayed (Volt, mA, time), with longer presseds it can also be used to select low charge current and LiFePO4.
• C cells has a tendency to slide off the plus pole, i.e. some aluminium foil must used to get a stable connection.
• The charger has two charge circuit, i.e. the slots are independent.

LiIon charging



The charger does a simulated CC/CV charger with a 50mA termination, this is fine.
I do not know where the jump in current comes from, it does make the charging a bit slower, but does not affect the quality of the charging.



The other channel does also have a CC/CV curve, but this time the termination current is 100mA





The charge time varies with capacity.



Selecting low current mode will reduce the peak charge current to 300mA, due to the variation in termination current it is a bit difficult to say if it is lower.



With my old 16340 cell the charger is a bit slow to reduce charge current whne charging at 0.5A.



Reducing current to 0.3A looks much better.





Both the 18350 and the 14500 is fine.



This charger will not reduce current when fully loaded, it chargers with full speed.



When using the DC input the charger needs about 0.6A. Notice the temperature is about the same with DC supply as with mains supply, i.e. the build in mains supply do not generate much heat.



M1: 35,2°C, M2: 32,6°C, M3: 41,7°C, M4: 44,7°C, HS1: 52,2°C



The charger need some time to start a charge.



The charger measures voltage with current off.





IFR (LiFePO4) charging

Holding the MODE button pressed for about 2 second will switch to LiFePO4 mode.



The charge voltage is too high, but this is not as critical with LiFePO4 as with ordinary LiIon batteries. The charge is a CC/CV charge with termination at about 100mA and no trickle charge.
The voltage is no accident, the charger is marked 3.7 volt for LiFePO4 charge.



NiMH charging



The NiMH charging stops on -dv/dt and do not use trickle charge.



The other channel works the same.



The eneloop XX needs a bit more time.



Powerex also terminated on -dv/dt.



The charger also terminates correctly when charging with 300mA (very good).



Of course the AAA cells terminates correctly, but the charger was a bit slow to terminate, i.e. the cell get warm.



With -dv/dt termination it takes some time to detect a full battery, but this charger is very slow with 26 minutes.



No reduction in current with two cells.



Charging NiMH uses less current on the DC input, compared to LiIon cells, only about 0.35A.



M1: 32,6°C, M2: 37,1°C, M3: 38,5°C, M4: 43,6°C, HS1: 50,1°C
The side with the two inductors for the charge circuit get significantly warmer.



The charger uses a low test current, probably to check for LiIon/NiMH, before it switches to the full charge current.



Voltage is measured with current turned off.






LiIon+NiMH charging

Charging one NiMH and one LiIon at the same time works fine.



Here with measurements from NiMH.



Here with measurements from LiIon, except temperature that is placed on the NiMH.




Testing the mains input with 2500 volt and 5000 volt between mains and low volt side, did not show any safety problems.



Conclusion

The charger does a good charging on both LiIon, LiFePO4 and NiMH.
The charge can be used for 26650 cells, but are not ideal for it, I would have liked the slots 2 mm longer, some protected 26650 are rather long.
I like the display, but it is a bit technical to look at and it only shows data for one channel at a time.

The D2 is a good universal charger and the low mode makes it better for small cells than the i2. The 0.5A charge current makes it a slow charger for large cells.



Notes

The charger was supplied by a Nitecore for review.

Review of old i4 (V2)

Here is an explanation on how I did the above charge curves: How do I test a charger