An Informal look at the Eneloop NC-MQNO5U Charger

I started looking at this charger and ran some tests.

Here is the set up:

Charge in the Eneloop charger and discharge at 0.5 amps on the C-9000.

First run involved charging my Sanyo 2500 mAh cells. I charged them in the Eneloop charger, let them rest for 30 minutes, then discharged them on the C-9000.

The results from charging them on the Eneloop charger are as follows:

2113 mAh
2130
2100
2125

I then charged the same cells on the C-9000 at 1000 mA. Let it top off for 2 hours, rest for 30 minutes, then discharged them on the C-9000 at 0.5 amps.

The results from charging on the C-9000 were:

2303
2279
2299
2266

With 2500 mAh cells, I got a fuller charge on the C-9000.

I then moved on to some Eneloop cells.

The results from charging them in the Eneloop charger:

1890
1918
1928
1893

Once again I charged them in the C-9000 and ended up with:

1891
1926
1926
1899

In this case, both chargers seem to have charged to about the same capacity.

I am going to see what happens when you have 2 cells that are nearly full charging with 2 cells that are less full.

Tom

Is this the NC-MQN05U model? Looking forward to your tests if it is. I've been wondering how it handles charging multiple cells with differing states of discharge.

I was wondering the same....

Hi Tom,
Just wondering why you used a 1000 mA charge rate on the C-9000 instead of the 300 mA rate that the Sanyo charger uses. Also, you let them top off for 2 hours on the C-9000 after termination... did you do the same on the Sanyo, or pluck them right after termination? I guess since the light on the Sanyo doesn't extinguish until the last cell has peaked, the other cells got at least a little trickle charge.

I figure you must have your reasons.. teach me, wise one. :bow:

Hello FlashCrazy,

I used the default charging for both chargers.

I believe the Eneloop charger simply shuts off after charging. I did leave it for a while after the light went off, but from the results it appears that it charges then shuts off.

The main reason for using 1000 mA on the C-9000 is that the battery manufacturers (including Sanyo) recommend charging in the 0.5 - 1.0C range. 1000 mA is 0.5C for the Eneloop cells.

Tom

Update:

I installed two Eneloop cells in the charger and fully charged them. I then stuck two more Eneloop cells in and waited until the light went out. Discharging them on the C-9000 revealed that all 4 cells were completely charged.

I initially used slots 1 and 3, then put cells in 2 and 4.

The discharged values were very similar to what I reported earlier for the Eneloop cells.

I think it is safe to say that this charger has independent charging channels.

Tom

Silverfox,

Thanks for doing the test. It is very helpful. So after the two initial batteries were charged and the light went off...the light came on again when the second set were put in...Correct? Do you think there could be any chance of the original 2 becoming overcharged?

Hello Dave,

I actually unplugged the unit while I was sticking the second pair of cells in. After they were in, I plugged the unit back in.

I am not sure how this charger terminates the charge, so I don't know if the originally fully charged cells were over charged or not. By the time the other cells were fully charged, the original cells had not heated up, nor were they at a higher voltage. Both of these things indicate that they were not over charged.

Tom

SilverFox said:

I started looking at this charger and ran some tests.

Here is the set up:

Charge in the Eneloop charger and discharge at 0.5 amps on the C-9000.

First run involved charging my Sanyo 2500 mAh cells. I charged them in the Eneloop charger, let them rest for 30 minutes, then discharged them on the C-9000.

The results from charging them on the Eneloop charger are as follows:

2113 mAh
2130
2100
2125

I then charged the same cells on the C-9000 at 1000 mA. Let it top off for 2 hours, rest for 30 minutes, then discharged them on the C-9000 at 0.5 amps.

The results from charging on the C-9000 were:

2303
2279
2299
2266

With 2500 mAh cells, I got a fuller charge on the C-9000.

Click to expand...

I've never known the MQN05 to exceed 7 hours during any charge, which makes me wonder if it isn't timing out with cells with a higher capacity than the Eneloop.

Did you happen to notice the duration of the charge with the 2500 mAh cells?

Hello Bones,

I did not keep track of charging times. Sorry.

Tom

A while back, I put 4 AAA batteries of different states of charge on this charger and probed each with a volt meter. I concluded it was an independent channel charger since the voltage of each battery was quite different throughout the charge. I happened to catch when one of them peaked (well right before anyway), and then after when that particular battery's voltage measured slightly less. The rest continued on with their charge.

I could hear the charger "pulsing" during charge... it was a somewhat high pitched intermittent buzz for a split second, every second or so. I could hear the same sound after the charger's light extinguished, although less frequent. I was pretty sure the charger was trickle charging after termination.

Well, today I tested it using an ammeter. I put one AAA Eneloop in the charger. During charge, the charger pulsed the battery with 610 mA for about a 1/4 second, then rested for 3/4 seconds, then pulsed again, rested, etc. Averaged out, this correlates with the 150 mA charge rated listed on the back of the charger for AAA's.

When the charger light extinguished, the charger pulsed the battery with anywhere from 10 to 40 mA for about a 1/4 second, then rested for 8 seconds, then repeated. It continued this cycle for one minute, then rested for a full minute. It then pulsed again as before for another minute, then rested a minute. This cycle repeated for as long as I had the battery in place. I took it out after about 20 minutes. I'm not sure one would call this a trickle charge, maybe more of a "maintenance" charge. Pretty cool, nonetheless.

Hello FlashCrazy,

Interesting...

I suppose the next question is if it every completely stops charging...

However, as you have indicated, the maintenance charge is quite low.

You didn't happen to notice how it terminates the charge did you?

Tom

SilverFox said:

Hello FlashCrazy,

Interesting...

I suppose the next question is if it every completely stops charging...

However, as you have indicated, the maintenance charge is quite low.

You didn't happen to notice how it terminates the charge did you?

Tom

Click to expand...

I'll have to test again and leave the battery in for a few hours to see if it ever completely shuts off. I didn't notice how it terminates, so maybe on the next test I'll be able to catch the battery peaking.

Update:

I left the cells in the charger, and the charger plugged in for 3 days. I pulled a cell and it was at 1.45 volts. It appears that this charger does continue to trickle charge.

After a few hours, the cell I pulled was at 1.43 volts and dropping.

Tom

Update:

This morning I took the cell that I had pulled from the charger and put it back in. The voltage had dropped to 1.42 volts. The light on the charge lit up and it continued to charge the cell for about 4 hours. The cell heated up to around 105 F. The cell next to it heated up a little, and the other two cells remained at room temperature.

Let's see now, this charger charges at 300 mA, I charged my fully charged cell for an additional 4 hours, so I put in an additional 1200 mAh that went to heating the cell up.

I would classify this as a missed termination.

Tom

I got some time to test the charger a little more the other day. I happened to catch a cell peaking (a AAA). To me, it looked like it was terminating on a 0 Delta V basis, but I guess it'd be really hard to tell with just my DMM. It peaked at 1.565 volts, then the charger light went off. I didn't notice it drop in voltage right before the light went off, but again, I can't be sure with the equipment I was using.

I left the cell on the charger for the rest of the day (11 hours) and noticed it was still trickle charging. Unplugged it and went to bed. Tom stated his continuted to trickle charge for 3 days, so it's safe to say that there's no safety timer.

Tom, I don't think you had a missed termination... I think you were just using one of those Energizers that loses about a billion mAH overnight due to high self-discharge! :lolsign:
Of couse I'm kidding.

Out of curiosity, when you charged the full cell, did you place the cell in the charger and then plug in the charger... or did you already have the charger plugged in and then put the cell in?

Hello FlashCrazy,

First of all, I don't have any of those "crap" Energizer 2500 mAh cells left... :nana:

I am charging Eneloop cells.

I had 3 cells trickle charging with the light off and simply put the 4th cell back in. The light went on, the cell warmed up, and about 4 hours later it shut off.

Tom

SilverFox said:

I would classify this as a missed termination.

Click to expand...

Most interesting Silverfox...

Would you care to speculate on what caused the charge to end after 4 hours?

This is also the first report I've noted of a missed (or delayed) termination, even on a cell that was already fully charged when inserted in the MQN05.

I haven't been able to get a fully charged cell to charge longer than 3/4 of an hour thus far, so I will have to try to duplicate your results by duplicating the same conditions.

I am also curious as to how the improved MH-C9000 would do with the same set of cells under the same circumstances, particularly with regards to temperature.

It would be even more interesting to see how it would do with the same set of cells with three different charge rates, being 300mAh, .5C and 1C.

Hello Bones,

The battery manufacturers recommend charging NiMh cells in the 0.5 - 1.0C range. I speculate that the charge termination was missed because the low charge rate of 0.15C does not produce a very strong end of charge signal.

I just put the same cells in the C-9000 at a charging rate of 300 mA. The cells had been off the Eneloop charger for about 4 hours. The C-9000 terminated the charge in around 30 seconds.

Tom

Update:

I pulled the Eneloop charger from power, let the cells rest for a couple of hours, then plugged it back in. All 4 cells terminated in 48 minutes this time. This still seems like a long time, but is a lot better than 4 hours.

Tom