Capacity of new Eneloops charged with Maha C9000

[Ohmic]

Hello all, I do hope you can offer some advice/opinions in the matter I have just experienced.

I had purchased a new packet of 4AA Eneloops (Manufactured September, 2009).

I opened these up and popped all 4 into the C9000.

I thought it best to run the break in, but since the charger is also brand new, impatience got the better of me. I proceeded to discharge each cell at 0.5C (1 Ampere).

The charger tells me it pulled approx 1600mAh from each cell, I thought this was quite normal considering they never come fully charged. After they were discharged, I began to charge them with the simple 'charge' command at 0.4C (800mA).

These were my results for each of the 4 cells after 'done' was indicated and charging ceased:

1777mAh
1873mAh
1894mAh
1876mAh

How do these values sound? Is it true generally the capacity will reach it's peak after a few cycles? I am not concerned about my findings, but was perhaps expecting a little more. I was also expecting less variation between cells, is it unreasonable to think this?

(I do understand that the break in would have probably been better for these new cells, but as said earlier, I was keen to see this new charger in action).

...also, I see the 'break in' mode first charges, then discharges and then charges again. Does this mean that even though Eneloops come charged when brand new, they still need to be discharged prior to running the 'break in' mode?

Thankyou all very muchlovecpf

 

[VidPro]

differences in charging and discharge testing via the 9000.
hopefully i say this right
The 9000 and a few other maha chargers have a voltage peak cutoff point. so it doesnt have to OVERcharge to reach a stop point (v-drop). That makes some difference between it and other chargers. being voltage safety type point, it also can vary the charge put in Depending on the resistance of the cell, and the charge rate used. Did you allow topping after cutoff?

The 9000 also doesnt discharge "As Far" as some other chargers and testing equiptment.

the results your getting are somewhat similar/normal, with that 1777 one being strange, which you should just move to another slot and test again.

as far as it needing more cycles? it is unliky to jump up to some 2000 (displayed number), using the SAME testing you just used. Did you allow topping after cutoff?
What your doing sounds just fine, 3/4s of your results are normal.

Enloops on the first full cycle (discharge/charge first) , usually have an actual capacity of ~2000 each of them, from End to End , but not all testing devices work from end to end, which is sometimes a better thing, 3/4s of your cells probably have the full ~2000 capacity.

Enloops dont "need" break-in cycles, even older long term shelved ones didnt need break-in, but we do it anyways because we can, and its in the book hey it will do a one time full cycling of the chemicals, and get it all ready to use, all you have to have is the time to do it. "Break-in" uses a slow charge method, so the voltage peak cutoff wont effect results as much, a slow discharge rate will also take the cell down further when using the same voltage cut-off point. so TRY-It , its fun.

and somone else will be able to tell you much more.

 

[Mr Happy]

These were my results for each of the 4 cells after 'done' was indicated and charging ceased:

1777mAh
1873mAh
1894mAh
1876mAh

How do these values sound?

They seem very typical. The C9000 is unusual in that it slightly undercharges cells up to the 'Done' point. If you leave the cells on the charger for another two hours they will get topped off to a fuller charge.

Also a break-in cycle on the C9000 will always report a higher capacity value than a normal charge/discharge cycle. When I run a break-in I always like to discharge the cells first, though it's not strictly necessary.

 

[JaguarDave-in-Oz]

I get about 1800 - 1850 on my eneloops. They are on their third cycle. I didn't bother with break-in but I have discharged them completely before each charge.

 

[Databyter]

I hear that they improve in performance just a little bit after a moderate amount of cycles. Not sure how many, but they improve in capacity before they start to decline at some point.

 

[jonnyfgroove]

Was the 1777 from slot 1? On my C9000, slot 1 always comes out lower when doing a regular charge. Maybe Ohmic's is the same.

 

[Ohmic]

Was the 1777 from slot 1? On my C9000, slot 1 always comes out lower when doing a regular charge. Maybe Ohmic's is the same.

Actually, yes. The 1777mAh cell was indeed charged in slot 1.

Did you allow topping after cutoff?

I did not know about this feature. When I simply came back inside to the charger I noticed all 4 had been 'done'. I guess that they may have been done for 5 -10 minutes or so.

I did not think to leave them in there much longer after the charge had completed.

Are you saying that even when 'done' is displayed, the charger will still trickle current into the cell and continually fill it up slowly?

 

[VidPro]

many chargers after termination, finish up all the rest of the chemicals that will change , with a slow topping method, this usually takes 1-2 hours. with the 9000 i forget the actual time :-(
yes chargers can say done , show Green lights and still be sitting there topping off the cell afterwards. some will continue to top-off at a slow rate , non-stop, forever and ever.

it is VERY easy to stuff a voltmeter to the ends of the cells when they are charging and when topping off and all, much easier than getting the ampmeter "in Between" the charger and the cells.
you can hook up a voltmeter permenetally, or just measure the cell itself a few times.
when charging the voltages of the cell/charge will creep up
if it V-drops you could see the voltage go down a tiny bit
when it goes to topping, voltages will stabalise and droop a bit
when it has actually stopped, voltages will drop quite a bit then stabalise at resting.
ALL voltages your reading will be inclusive of the charge existing pumping up the cells actual resting voltage, untill the charge it self no longer exists.

so when you dont get or have displayed voltages shown or accessable, a quick peek with a meter is Fun too

 

[Burgess]

Was the 1777 from slot 1?
On my C9000, slot 1 always comes out lower when doing a regular charge.

Mine does this, also.


I've learned not to "obsess" too much about it.

Just use 'em, and enjoy yer' Guilt-Free Lumens !

:thumbsup:
_

 

[jcvjcvjcvjcv]

Lol, I get continuosly 2000-2200 mAh from my Eneloops in my BC-900 (Conrad IPC-1). But the damn thing tops off at ~1.52 Volts...

The non-LSD cells finish off at a lower voltage.

 

[csa]

Sounds like pretty typical results. Enjoy your cells!

 

[Ohmic]

Sounds like pretty typical results. Enjoy your cells!

I certainly will:thumbsup:

...but I think I will enjoy this charger more, Will have to experiment with different charge rates and the like.

Will also have to move cells around to different slots to see if it really is the 1st slot that is not charging fully. One of the small joys of owning such nice products.

Thankyou all who have contributed:twothumbs

 

[jonnyfgroove]

Mine does this, also.


I've learned not to "obsess" too much about it.

Just use 'em, and enjoy yer' Guilt-Free Lumens !

:thumbsup:
_

I totally agree! I always let my cells do the two hour top off charge anyway. Also, when I do a break in cycle it does not happen. Only on a regular charge.

 

[Ohmic]

Bumping this thread to ask for some fellow opinions.

After many cells charged in this charger (Maha C9000), it appears that slot 1 (furthest left) ALWAYS reads around 100mAh lower than the other 3 slots.

The other 3 slots are always very close (around 20-30mAh)

Would a product exchange be justified in this case? I will contact Maha and see what they say.

My only concern is that one cell is always going to be down on the others and hence could be prone to cell reverse charge. However I always turn off the flashlight at the first sign of dimming (TK40 and LD20).

For some reason this aberration with slot 1 seems unacceptable as I would've though this charge inconsitency is no better than cheap chargers which charge cells in series.

Glad to know what everyone thinks about this, and if it is indeed worthy of a warranty claim.

Thanks all and good day:twothumbs:twothumbs

 

[Bones]

Capacity measurements are directly related to the rate, duration and type of charge, the rate and type of discharge, and the methodology employed by the charger to terminate both the charge and the discharge.

For these reasons, a standard protocol was developed by the IEC which all manufacturers use to rate the capacity of their cells. If you're not following this protocol, your measurements will be skewed and therefore irrelevant insofar as comparing stated versus actual capacity:

http://www.candlepowerforums.com ... post3325862

The break-in cycle of the MH-C9000 is intended to approximate the IEC standard. This is specifically not the case with any of its other protocols.

 

[Ohmic]

Thanks Bones for the reply, I enjoyed reading your post and have read more into the IEC standard for measuring cell capacity, however I do not understand how this correlates to my concern.

In my experience, The C9000 will display 'done' at 1800mAh or so for AA eneloops charged at 0.5 - 1.0C, this is of little concern to me, as I never expected the full 2000mAh (and I fully understand why the 2000mAh capacity is not displayed), but my concern however lies in the charger appearing to not have equal charge characteristics among the slots (or bays if you prefer).

I have around 20 eneloops now on regular usage and rotation, and regardless of which one of these cells I choose to insert in slot 1, the results remain constant, that is, slot 1 is always 100-150mAh below the others.

My thoughts now tend to gravitate towards component tolerance issues within the charger itself, causing slot 1 to terminate charge early.

For example I believe this charger terminates charge at 1.47V, now if the component(s) responsible for determining this voltage in slot 1 are of different tolerance to the ones in the other 3 slots, then I can understand why this is occurring. This scenario is mere speculation on my part.

My concern is that despite my best efforts, my cells are not coming off charge balanced, and accuracy and equal charging characteristics are the reason I have bought this charger.

Like many others, I do not have time to use the 'break in' mode, and usually rely on a simple 0.5-1.0C fast charge.

:thanks::wave:

 

[Russel]

If you perform a discharge, making a note of which cell was charged in the first bay, do you see a difference in discharge capacity?

Do cells discharged in bay one consistently display a different capacity than the other three bays?

 

[Ohmic]

If you perform a discharge, making a note of which cell was charged in the first bay, do you see a difference in discharge capacity?

Do cells discharged in bay one consistently display a different capacity than the other three bays?

That's something I haven't done yet. So basically charge 4 cells, note charge put into the cell, then simply discharge them again? Easy.

I'll do this and report back:thumbsup:

 

[rookiedaddy]

One of my C9000 does exactly the reverse, slot 1 seems to always able to put in more charge 50-100ma and always seems to be the 1st to complete the charge, even if I put in the cells in reverse order 4, 3, 2, 1.

But as I normally leave cells there for another ~2 hours after display 'DONE' to get fully charged cells (I pull them when their Voltage start dropping below 1.47V), I have however notice all 4 cells Voltage is either the same or approx. 0.01V diff at resting. Of coz, this is no indication of the cells true capacity as I haven't got around to do any discharge test. Would be interesting to learn about your discharge test.

 

[Niconical]

I have around 20 eneloops now on regular usage and rotation, and regardless of which one of these cells I choose to insert in slot 1, the results remain constant, that is, slot 1 is always 100-150mAh below the others.

I found my slot 1 to be similar, and I narrowed it down to (what I believe to be) heat. Slot 1 gets the least hot of the 4 slots, and seems to put in the least charge (assuming 4 same-state cells) until DONE. However, when I discharge those same 4 I get even discharge numbers, so it's all good.