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Efest LUC Blu4 Charger Bench Test Results...a good, durable 1A Bluetooth charger

Discussion in 'Batteries and Chargers' started by Mooch, May 27, 2016.

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  1. Mooch

    Mooch Electron Wrangler Verified Member ECF Veteran

    Supporting member
    May 13, 2015
    This is a review of the build quality, durability, and safety of this charger. It is not a comprehensive review of all its features and functionality. These chargers were sent to me for free by Efest for the purposes of testing. Thank you!

    While the measurement and test data is objective, the conclusions and recommendations I make are only my personal opinion. Carefully research any charger you are considering using before purchasing.

    Testing chargers at their limits is dangerous and should never, ever, be attempted by anyone who has not thoroughly studied the dangers involved and how to minimize them.

    image.jpeg image.jpeg image.jpeg image.jpeg image.jpeg image.jpeg image.jpeg image.png

    Bottom Line
    The Efest LUC Blu4 is a good, durable 4-bay charger. Like any charger though, it has its subjective pros and cons depending on what you're looking for. It has 0.5A x 4 slot and 1.0A x 2 slot charging options, large red/green status LEDs, a small status screen, and a Bluetooth app to monitor charging. It does not display the mAh put back into each battery though. It can charge 10xxx-18xxx sized batteries, but not 26650's. Its charging is consistent and it doesn't overcharge or run too hot. It survived all my standard torture tests.

    • Size = 7.6" x 2.2" x 1.6"
    • Charger Weight = 234gms/8.3oz
    • AC Adapter Weight = 84gms/2.9oz
    • Available charging configurations = 4 slots @ 0.5A or 2 slots @ 1.0A.
    • Claimed protection = reverse polarity, low-voltage battery recovery, overcharging.
    • Charger shuts off when the current has dropped to 10% of the charging current setting.

    Design & Construction
    • The case feels sturdy and light for its size.
    • What appear to be cooling slots on the bottom/sides don't go all the way through the case, i.e., they don't provide any cooling.
    • Large, easy to see red/green status LED for each slot.
    • There are two microprocessors, one running the chargers and another handling the display and Bluetooth module. The charger circuit's microprocessor was hand soldered.
    • The circuit boards appear to be assembled to standard commercial/consumer product standards and were properly soldered and cleaned fairly well.
    • All of the internal parts were well mounted and supported.
    • The heaviest components, the inductors for each charger circuit, were held in place with an RTV-like goop to prevent stress from vibration and shock and to minimize buzzing/squealing during operation.
    • The AC adaptor plug (USA 2-prong) has its prongs at a right angle to what I've normally seen in small adaptors. This means it will take up space for at least two outlets on most power strips.

    Use and Accuracy
    • All functions performed as expected.
    • There are four independent charging circuits. Anything you do with one circuit (slot) will not affect another one.
    • The Bluetooth app shows the charging current and voltage for all four slots but only holds display data for two channels at a time when looking at the charging graph screens. It takes several seconds to load the data for the other channels each time you view them.
    • The voltage displays seem to be updated every 25 seconds but since the battery voltages are not changing quickly this shouldn't be a problem.
    • The batteries are charged to 4.22V-4.24V. This isn't a big problem, it maximizes capacity, but I'd prefer it to stop 4.20V or a bit lower to help extend battery life.
    • The Bluetooth app and the on-board display never read higher than 4.20V though.
    • The circuit board components never exceeded 60°C and the outside of the case never exceeded 35°C max. This is well below the point where damage could occur to the components.
    • Covering the charger during the entire charging period with a doubled over towel only raised the temperature about 4°C. This is probably due to there being no cooling slots in the case so there was little difference between an uncovered unit and a covered one.
    • When charging four batteries they reached temperatures about 4°C higher than they do in the Efest LUC V4 charger. This is not a lot but needs to be noted. I think this is due to the deeper individual slots in this charger holding in the heat from the battery a bit better.
    • No high-pitched squealing or buzzing was heard at any time during charging.

    Durability Testing
    • There was no wrap damage to 25R's or HG2's after 20 insertions/removals other than slight dents in the top insulating ring.
    • No damage to, or bending of, the springs and negative contacts occurred after pulling back each negative contact 100 times and letting it slam forward.
    • Dropped the unit from 3' onto a wooden floor 10 times onto all corners and the face and rear of the charger without any damage or malfunctions.
    • Dropped the unit from 6' onto a tile floor 3 times onto different corners without any damage or malfunctions other than slight scuff marks. This finished my standard torture testing.
    • Just to see what happened, another three drops from 6' onto a tile floor were done. The second drop finally dislodged the display and button, forcing the button inside the unit and the display moving about 1/2" to the side. The charger still functioned properly though and the button and display could be moved back into place if you were comfortable with opening up the charger.

    Safety Testing
    • An overdischarged battery at 2.0V was properly slow charged at 0.03A until it hit about 2.9V. It was then charged at the selected rate, 0.5A or 1.0A.
    • Fully charged batteries were inserted and removed repeatedly but were never recharged above 4.24V.
    • The AC adaptor was unplugged and plugged back in several times during charging to see if it caused the charger to lock up or malfunction. Once the charger reset after the power was restored it continued charging normally.
    • Four batteries were left in and the AC power removed overnight. The charger did not draw anything more than a tiny amount of current from the batteries, about 100uA according to Efest. The battery voltage only dropped about 0.01V.
    • There is no safety timer to prevent continuous charging in case a bad battery, unchargeable due to being damaged, is inserted. This is not a common safety feature in most lower cost chargers though.
    • There is no independent backup overvoltage protection circuitry to prevent overcharging in case the microprocessor fails or the charger locks up. This is not a common safety feature in lower cost chargers though.

    Wish List
    • Have an option to choose a charging voltage of 4.10V (to extend battery life) or 4.20V (to maximize capacity).
    • Elevate the red/green status LEDs, just a bit so they can be seen from across the room without standing the charger up on its side.
    • Add a blinking red LED function to indicate when recovering a low voltage battery and not doing normal charging.
    • Add half-circle cutouts at the positive end of each slot to make it easier to hook a finger on the battery to pull it out.
    • Display the mAh put back into each battery during charging.
    • Make the status screen brighter.
    • Add secondary overvoltage protection and a safety timer. This increases cost though.

    To compare the results for all the chargers I've tested:
    Li-Ion Charger Safety and Durability Test Results | E-Cigarette Forum

    Some fantastic charger testing:
    Batteries and chargers
    • Like Like x 6
  2. marquee

    marquee Full Member

    Aug 20, 2014
    Utrecht, NL
    Thanks again for testing Mooch!
    • Like Like x 1
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