Test/Review of Charger Efest LUC V4

Batteries and Chargers Chargers
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Charger Efest LUC V4

Efest has modified this charger and a update review has been published






Efest has been building a line of chargers from single cell to four cell with fixed and variable current, this is a 4 channel LiIon charger with 3 charge currents.




The charger comes in a brown cardboard box with a list of supported batteries.



In the box is the charger, a power supply and a manual.



The charger is powered from 12 volt and has an usb output. The usb output can only be activated when no power is connected to the input.



At 0.5 and 1A current the charger can charge 4 batteries. The two arrows are animated while charging.
The voltage display shows the battery voltage (The 8 is due to mixing of digits during long exposure, not because the display showed 8).

Below the display under the word "Charger" is the button, it is used to select charge current and to activate usb output (when possible).




At 2A current only the two center slots can be used, this is clearly illustrated on the display.



Usb output uses a icon in the center. This does not indicate what slot to use (It is slot #2).



The sliders for the battery work smoothly and can accept batteries from 30mm to 70.5mm.



Between the batteries is a list of supported battery sizes, but the 10440 size is only valid for IMR cells.





The charger can handle 70 mm long batteries including flat top cells.
The charger is rated for 10440 batteries, but due to the charger current it is only recommended to charge IMR 10440.
Note: Using to high charge current will not make the batteries explode, but will reduce lifetime of the batteries.



Measurements

LiIon at 4.2V (ICR/IMR)

  • When not connected to power it will discharges with up to 0.09mA, except the USB out channel that will discharge with 0.15mA.
  • When the battery is full the charger will discharge with about 0.1mA.
  • If the voltage drops below 4.05 volt the charging will restart.
  • Power cycling or reinsertion of the battery will restart charging.
  • At about 0.65 volt the charger will detect a battery and start charging with 150mA
  • The current will drop to 60mA at 3 volt, where the full charge current is applied.
  • The voltmeter is limited to 4.2 volt, if the voltage get much above 4.2 volt it will show 0.0 volt.
  • The voltmeter shows about 0.06 volt to low.
  • The channels on the charger are independent, i.e. there are small differences between them.





The charger does a good CC/CV charge curve with a good termination current, but it charger to 4.28 volt, not 4.20 volt (Maximum 4.25 volt), this is not good.



With 1A it is exactly the same, very good CC/CV charge curve, but to high a voltage.



It looks like the over charge protection in the 2600mAh cell tripped (The other cells I test with are unprotected).



The 3400mAh is exactly the same as the 3100mAh cell, to high charge voltage.



With 2A current and a Efest 26650, the result is again the same. The termination is slow, probably due to the high voltage.



With my old IMR 16340 cell the termination is also slow.





The other 3 slots looks close to the first slot, all slots are over charging.





M1: 39,1°C, M2: 40,9°C, M3: 40,2°C, M4: 40,2°C, M5: 41,5°C, HS1: 57,2°C

The heat from the charger is distributed fairly even across the batteries.





The charger does slowly ramp the current to the selected charger current, changing the selection will start a new ramp from 0.



USB output

  • When using usb output, the symbol will flash when the battery is nearly empty
  • When usb output is on, but unloaded, it will draw about 12mA.
  • Usb output turns off after about 30 seconds with a load below 30mA.
  • It is not possible to turn off the usb output with the switch.
  • When mains power is connected, the usb output is off.
  • Usb output is coded as Apple 1A
  • Usb output will turn off when overloaded





As usual I do a load sweep first, to see how the output works at different loads. The LUC turns off at 1.15A, this is good for a 1A rated output.



Only one battery is used for usb output (Slot #2), here I am running with a 0.5A load, the output turns off when the battery is down to just over 3 volt. The efficiency is good at 85% to 90%.



2600mAh has shorter runtime.



3400mAh has longer runtime.



Increasing the load to 1A, show that the output has some trouble just before the battery is empty.



With 7mV rms noise and 108 mV peak-peak noise the output voltage is good.



With 1A load the rms noise increases to 9mV and the peak-peak to 110mV, again a good value. The trouble just before the battery is empty will, of course, have much higher noise.


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



Conclusion

The charger uses the correct algorithm has a good termination current and I like the design, but the high charge voltage is not acceptable.
The usb output does also work fine, but I do not know how much use it is in this type of charger. If it had been power when the charger was powered, it would probably be more useful.

If Efest fixes the high charge voltage it will be a good LiIon charger, but before that happens it is not very good.



Notes

The charge was supplied by Efest for review.

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

Read more about how I test USB power supplies and chargers

2

Sigh… Why ruin an otherwise excellent charger? Some major fail here.

Thanks for the review HKJ, another charger to avoid!

(Would be great for 4.30V cells though.)

3

thanks for the measurements!! :)

4

Thanks!

5

Thanks! :)

Too bad about the high charge voltage. It looked good..

6

I really like the look of this one, had high hopes coming from Efest that it would be spot on. Was eager to purchase it to go along with my growing collection of Efest cells. But, alas, they have made a crucial mistake and it will not be joining it’s Efest counterparts in my line-up. :frowning:

I wonder, now, if they will listen and fix this glaring issue. Perhaps a note to Kiko is in order…

7

Thanks for yet another great review and your great effort :beer:

Concurred with ryansoh3, that this charger is best suited for those special 4.3v 18650s’

8

Is there a switch on the side to select 2A? Can you explain how to set it for 2A charge?

I might have missed it. thanks

I know my ThruNite MCC-4 charger frequently charges over 4.20V, but I don't recall if it's over 4.25V. Ok, I tested them now.

I posted my charge results (termination voltages) on HKJ's MCC-4 review.

9

No, you just push the switch (Under the word "charger"), it goes between 0.5A, 1A and 2A.

Oops, it is missing from my review

I expect the main problem is tolerances on the reference, i.e. some chargers will go to 4.28 volt, other will go to 4.23 volt or something else.

10

News from Efest…

I did indeed write to them about the overcharging issue and they sent me a lengthy message back responding that a manager decided to up the Voltage charge cut-off as he thought some of the newest cells were not getting fully charged. As this has turned out to be a mistake, over the past 2 weeks they have reversed that decision, with all chargers coming now with the proper cut-off Voltage.

I was informed that new Chargers have been sent to HKJ for testing and anxiously await the outcome of this, with HKJ being busy with a full schedule undoubtedly.

Thanks Henrik, really appreciate all the hard work.

And thanks especially to Efest, for listening and ACTING! :slight_smile: Looking forward to getting one of these LUC Chargers, but will await confirmation that they are, indeed, corrected.

11

Awesome, thanks for the update.

No wonder the voltage was very high; this wasn’t a bad chip, it was intentional!

It would be very interesting to have different editions of the chargers for the newer cells requiring 4.30 and 4.35V. :slight_smile:

12

In that case, they can now make a 4.2V AND a 4.3V version!

13

Thanks for the review HKJ! So what's the "street price" of this charger?

EDIT - Quick Google-fu shows it going for about $36 - $40 + shipping. Seems a little high.

Also, question: the USB output is only powered by one of the 4 slots? That seems a little dumb.

-Garry

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Garry, the USB slot is used to power up your phone or whatever. It seems to me that way anyway, it’ll run your phone off a single 18650 cell. :wink:

Please correct me if I am wrong, but that’s what I get out of it. :slight_smile:

Edit: at the very end of his review, HKJ remarks about the USB “output”

15

I understand that. I'm thinking more along the lines of "power bank" use where you could load up anywhere from 1 to 4 cells (for increased capacity) and use it as a USB charger source.

-Garry

16

But then the 4 bays would need to be connected in parallel, not what you want when charging 4 Li-ions, right?

17

Am I? I thought we were talking about the functionality of the Efest LUC V4 charger?

Seems to me that for a box to run 4 cells in parallel for a supply, it would be bad or not feasible to run separate charging bays…how could the charging bays be separate if they were connected? Too much multi-tasking can be a bad thing! Anyway, I wouldn’t use a 4 bay 18650 as a power supply so it’s not of interest to me. Wouldn’t use it that way even if it could do it.

Are you recommending a charger? Hmmm, maybe You’re off topic, Kreisl! :stuck_out_tongue:

Merry Christmas Kreisl, and to all a good…oops, later!

18

i thought i was quoting someone else my bad *g*

i am not recommending a charger which exists only in our dreams, so no i am not recommending a charger other than the XTAR XP4 which i had positively reviewed :P

19

Why not get the Thrunite MCC-4? Aren't they about the same price? I think you can get the MCC-4 for about $40 (Amazon).

it also does NiMH cells - but the LUC does not.

I've got the MCC-4 if you have any questions.

20

I have dedicated chargers for my NiMH cells and would not mix the two. Dedication is what works for me, not multi-tasking. For my photography needs, I use Maha chargers. With 2 of their 8 bay chargers those needs are met.

I am also a brand loyal kind of guy. I like my Efest cells. I rely on my Efest cells, and I will also be happy to add an Efest charger to the SoShine S1 Max V3 that I am currently using, along with the single cell Cottonpickers chargers I also use. The Cottonpickers chargers have spoiled me by showing the voltage on their display, so I very much like that feature here in the Efest. I’m not going to say that I only use one brand of anything, but when I like a brand, I like to support that brand.

Dare I say this? Here of all places? It’s NOT about the money! :open_mouth: I want a product that is done right, that I can depend on, and if that means paying a bit more for it, or waiting for them to get it perfected, then so be it.

I’ve had my eye on the Thrunite since it came out, but it’s dual chemistry charging has held me back. I have a horrible memory. This leads to me making mistakes. I don’t like my equipment making decisions for me, so I limit my equipment to specific tasks in order to not get confused. Sometimes a problematic restriction, but it works for me so I stick with it.