Nitecore New i4 Intellicharger Charger Testing

WARNING: My test results only represent the chargers I tested and all comments are just my personal opinion. Charger design can change or assembly quality can vary at any time. Any charger can fail at any time, either from an internal issue or from a battery with a damaged wrap short-circuiting when being inserted. USE OF ANY CHARGER IS DONE AT YOUR OWN RISK. Carefully read the instructions and all safety warnings before using the charger. Never charge a battery unless the charger is on a non-flammable surface and you are around and awake the entire time. Never let a battery that is getting hot continue to charge. Never put a charger in a fire-resistant “LiPo bag” as that can easily cause the charger to overheat and fail. Double check that the battery wraps are in perfect condition before and after each time you use a charger. Remove all batteries when they are done charging and put them in non-conductive cases. Unplug the charger when not in use.

Summary: Two units tested. If you’re not worried about the cell voltage or whether your cells are being charged at 0.375A, 0.5A, or 0.75A (or you can memorize all the different charging current vs number of batteries vs battery slots used) then this charger can be used for 18350’s and 18650’s. Otherwise it’s incredibly confusing to use, runs too hot when charging four cells, and does not fit most 20700/21700 cells. 


SAFETY WARNING: According to the instructions using Battery Recovery Mode on a cell that is in reversed position (positive end down) can cause a fire or explosion. NEVER use Battery Recovery Mode without carefully confirming at least twice that your cell has been placed in its slot properly (positive end up).


Teardown photos: https://imgur.com/a/e649Mrp


Cell Fit

  • 20700/21700 = The sticker on the back of the unit says it’s “compatible” with 20700’s and 21700’s but most are too long and do not fit.
  • 18650 = All fit easily.
  • 18350/26650 = 18350’s fit but only two 26650’s at a time.
  • Like many chargers it is tough to get 18650 cells out at first if all the slots are filled.


Actual Charge Current (lowest and highest for the four channels on two chargers)

  • 0.375A Setting = 0.36A - 0.37A (pulsed at 0.71A - 0.74A for 5 sec on/5 sec off to average out).
  • 0.75A Setting = 0.71A - 0.74A (pulsed at 1.42A - 1.48A for 5 sec on/5 sec off to average out).
  • 1.5A Setting = 1.42A - 1.48A (output turns off for a few milliseconds every second)
  • Includes small drifting in value as the charger heats up.
  • This charger automatically divides batteries into two types, “small capacity” and “large capacity”. Small capacity is less than 1200mAh and shorter than 65mm in length. Large capacity is more than 1200mAh and equal to or greater than 65mm in length. The charge current is automatically chosen based on whether they are small/large capacity batteries and how many are charged at once. Please read the instructions for more details.
  • I tried 600mAh and 1200mAh 18350’s and all were identified as small capacity. Any 18650 or 26650 I tried was identified as large capacity. I did not have an 18650 with a capacity below 1200mAh but since this charger uses a length-detection negative contact setup all 65mm long cells are probably identified as large capacity.
  • If charging just one cell make sure you confirm that any 18650/26650 can be charged at 1.5A. I was unable to change that setting to something lower when charging just one cell.


Charging Current For Each Slot

  • This can change based on the number of cells being charged and their position.
  • Some charge current levels are reached by charging at double that current level but turning off the current for 1/2 the time (5 seconds on then 5 seconds off) to “average out” to the appropriate setting. This is not the best way to do things but it is acceptable.
  • 18350’s (“small capacity” cells)
  • Any one slot filled = 0.5A
  • Any two slots filled = 0.5A
  • First three slots filled = 0.375A/0.5A/0.375A/empty (0.375A is average of 0.75A pulsed at 5 sec on/5 sec off).
  • Four slots filled = All 0.375A (0.375A is average of 0.75A pulsed at 5 sec on/5 sec off).
  • 18650’s/26650’s (“large capacity” cells)
  • Any one slot filled = 1.5A (red LED is lit).
  • Two slots filled, slots 1+3 or 2+4 = 0.75A (0.75A is average of 1.5A pulsed at 5 sec on/5 sec off).
  • Two slots filled, slots 1+2, 2+3, 3+4, or 4+1 = 0.75A continuous each.
  • Three slots filled
  • empty/0.375A*/0.75A/0.375A*
  • 0.375A*/empty/0.375A*/0.75A
  • 0.75A/0.375A*/empty/0.375A*
  • 0.375A/0.75A*/0.375A/empty
  • *0.375A average by pulsing at 0.75A for 5 sec on/5 sec off
  • Four slots filled = 0.375A each by pulsing at 0.75A for 5 sec on/5 sec off.
  • One slot filled is always charged at 1.5A. I was unable to change this.
  • If you have two, three, or four slots filled you can change one slot to 1.5A. The others will turn off and wait until that cell is charged at 1.5A and then the other(s) will charge at the above listed levels.
  • If charging multiple “large capacity” cells then then last one gets charged at 1.5A once the others are done charging.


Max Charge Voltage (new Samsung 25R’s)

  • Ranged from 4.19V to 4.20V for all four channels of both units when set to 4.2V.
  • Ranged from 3.66V to 3.68V for all four channels of both units when set to 3.7V.
  • I was unable to test the accuracy when set to 4.35V. This is a rarely used setting for certain Li-Ion cells.
  • Older cells or those with low current ratings might stop charging at a lower voltage. This depends on the particular charger model and how it determines if the cell is fully charged or not. A lower voltage on its own is not a problem and can help increase cell life. But if a cell is starting to charge at lower and lower voltages over time it might indicate that the cell is reaching the end of its life.


Charge Progress Display

  • Up to 3.85V = 1 LED blinking.
  • 3.86V-3.90V = 1 LED solid, 1 LED blinking.
  • 3.91V-4.18V = 2 LEDs solid, 1 LED blinking.
  • 4.19V-4.20V = 3 LEDs solid, charging stopped. Top red LED turns off if you were charging at 1.5A.


Reverse Polarity Protection = PASS

  • One to four cells in various combinations of correct and reversed positions.
  • All four LEDs blink (three green, one red) when a cell is put in with reversed polarity (positive down).


Max Temperatures (for 4x0.375A or 2x0.75A charging)

  • Adapter = Not applicable, uses wall AC voltage.
  • Cells (Samsung 25R) = 34°C middle, 37°C top.
  • Case = 63°C and 73°C for the two units, quite hot.
  • Internal Components = 94°C, too hot.
  • In my opinion the temperature of the components internally is too high to ensure long life and good reliability forvall the units. Yours could last 20 years or it could last for just a short time. It’s just that the failure rate goes up as the temperature goes up, approximately doubling for each 10°C increase. What you get for the unit you buy is just luck of the draw.


Battery Recovery Mode

  • SAFETY WARNING: According to the instructions starting Battery Recovery Mode for a cell that is in reversed position (positive end down) can cause a fire or explosion. NEVER use Battery Recovery Mode without carefully confirming at least twice that your cell has been placed in its slot properly (positive end up).
  • Using a severely overdischarged Li-Ion cell at 0.3V resulted in all four LEDs blinking for that slot, indicating (I believe) it thought it was a Li-Ion cell. Pressed the C and V buttons to start Battery Recovery Mode and charging started at 1.5A with one green LED blinking. I would prefer that it not charge such a severely overdischarged cell so quickly. Many chargers use a very low charge current level until the cell is at 3V or so.
  • Starting with a severely overdischarged Li-Ion cell at 1.4V resulted in 2 green LEDs lighting up, indicating the charger thought it was a NiMH/NiCd cell. It then went to three solid green LEDs to indicate a fully charged NiMH/NiCd cell and turned off, leaving it at about 1.65V.
  • Starting with a severely overdischarged Li-Ion cell at 1.9V resulted in three solid green LEDs, indicating a fully charged cell, the charger thought it was an overcharged NiMH/NiCd cell I believe, and stopped. Pressing the C and V buttons to start Battery Recovery Mode started Li-Ion charging at 1.5A.
  • Do not try to charge any cell that is below 2.5V (it can be damaged) or when colder than 0°C/32°F (that can damage the cell) and always make sure the charger goes into Li-Ion mode after you put the cell in.
  • I don’t like an “activation” feature for overdischarged cells as they can be damaged if left below 2V or so and should not be recharged and used.


Drop Test = PASS

  • Ten drops from one meter high onto the face, back, and all corners of the device onto a hardwood floor.
  • Both units worked properly afterwards and no loose parts were rattling around inside either unit


Spring Snap-back Tests = PASS

The negative contacts (springs) were pulled all the way back and let snap forward, repeated 100 times for each unit.


Assembly Quality

  • The assembly looks pretty good, as does the soldering, but the bottom of the main board had lots of flux residue on it that was only partially washed away.


Comments

  • The contacts each have two rather pointed dimples that often get caught between the top contact of the cell and the top ring insulator. Keeping your battery wraps and top insulating rings in PERFECT condition is critical when using this charger.
  • The charger resets the voltage selection to what it thinks is appropriate every time you put a cell in. If you use LiFePO4 cells, charged to 3.7V, then you must reselect that lower charge voltage every single time you put a cell in to be charged.
  • I don’t think it would ever decide on its own that you have put in a cell that needs to be charged to 4.35V but make sure it hasn’t every time you charge. “Intelligent” chargers have some advantages but if they make the wrong choice that could be a safety issue.
  • I urge you to read the instructions at least a couple of times because this unit makes a lot of decisions on its own and if you want to know what those decisions might be then the instructions are critical.

END OF REPORT

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