Test/Review of Charger Enova All-21

Batteries and Chargers Chargers
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Charger Enova All-21





Enova has a long line of chargers with 2, 4 and 8 channels. This review is about one of the 2 channel chargers.



I got the charger without any box.



The charger has a mains input and a 12 volt input.



There is also a usb output.



The label on the charger says 4.22 volt, this is slightly to high for LiIon.
Charging a 10440 with 0.5A is not recommended (except for IMR types).



There is 3 leds to show charge state.



The battery slots are the usual construction and works acceptable.
It can handle batteries from 30mm to 69.8mm, this will give problems with some protected 26650 batteries.







The charger can handle 69.8 mm long batteries including flat top cells.
The current is too high for small cells.



Measurements

  • Below 0.7 volt the charger will not charge but flashed all 3 yellow leds.
  • Above 0.7 volt the charge will charge with full current.
  • Above 2.0 volt charger assumes LiIon battery.
  • Charger will not restart if voltage drops, but it will charge with about 1.5mA.
  • Charge will restart charging after power loss, or battery insertion (LiIon battery must be below 4 volt to initiate a charge).
  • When not connected to power it will drain about 13mA from a LiIon battery, but only 0.2mA from a NiMH battery.
  • When charging is finished the charger will charge with 0.4mA to the battery.



LiIon charge



The charger uses a simulated CC/CV charge profile with a 70mA termination.



The other channel works the same way.




The two other batteries does also charge fine.



My old 16340 cell is handled without any problems.




Same with the two other cells.



The charger will use full charge speed with two batteries.



The charger needs about 500mA when powered from 12V



M1: 33,0°C, M2: 33,4°C, M3: 45,9°C, M4: 49,3°C, M5: 48,1°C, HS1: 55,0°C
The batteries stays fairly cool during charge.



The charger starts in about 4 second.





NiMH charge



This charger terminates on voltage and the charged capacity is slightly low.



Both channels works the same way.





Both EneloopXX and powerex will also termination on voltage.



Same with the AAA cell.



Using a voltage termination the charger is very fast to terminate on a full cell, here it is done in 3 minutes.



No problem with two batteries.



For charging NiMH it needs about 300mA from a 12V power supply.




M1: 35,5°C, M2: 35,9°C, M3: 44,8°C, M4: 45,6°C, M5: 45,1°C, HS1: 51,6°C




NiMH also starts in 4 seconds.



NiMH uses measuring pauses.




LiIon & NiMH mixed charge

The charger supports charging a mix of NiMH and LiIon batteries at the same time.



The NiMH takes the same time to charge as above.



As can be seen in the current curve there is a slight change in current when the NiMH finish.



USB output

  • The charger can use any battery slot for usb output.
  • With batteries in more slots, they will be used concurrently
  • USB output is always on when charger is unpowered and is loaded with at least one battery.
  • When unloaded it will draw 13mA from the battery.
  • USB output is codes as Apple 1A.







The usb output is rated for 0.7A with one battery and can deliver a bit above 1A with one battery, this looks fine but I would have liked a overload protection.
There is a minor difference in maximum current between the two channels.



With two batteries it is rated for 1A and can deliver 2A.





Output looks fine with 0.5A load. It limits the battery discharge to about 2.75 volt, but does not turn the output off.




Different battery capacity will, of course, give different runtimes.



Using two batteries will double the runtime. Because the two usb output circuit are slightly different, it will drain one battery first, then the other battery.
The efficiency curve is not corrent, because I only measure current for one battery.



Increasing the current to 1A with one battery does not work perfectly, output will drop to early.



It works better with two batteries, but still not perfect. When the first battery is empty it has trouble maintaining output.




The noise is very low on the usb output: 4.8mV rms and 66mVpp



It does increase slightly with higher load (1A): 8.5mV rms and 76mVpp (With two batteries the Vpp is 90mVpp),


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



Conclusion

The charger is a good LiIon charger, with NiMH batteries it will be slightly below full charge because it uses voltage termination without any top-off charge.
The usb output is acceptable. It has low noise and can deliver 1A with two batteries. The termination is not very good and I am missing a indication when output is on and overload protection.



Notes

The charger was supplied by Enova for a 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