[UnknownVT]

Here's the discharged readings from last night: This is from a Fully charged set of Eneloops....
Here's the Recharge Readings this morning: (Same batteries in same slots)

Very nice - thank you.

This shows that although the total charge capacity is an indication -
the actual (dis)charge capacity is slightly less.

What the Maha/PowerEX C9000 charges total is different from the actual capacity of the battery -
now with hindsight this is not surprising, as in charging (the system can't be 100% efficient) there must be some losses - eg: heat.

But your readings show that your eneloops (individually) are in good shape.

It used to be that eneloops are delivered (ie: in unopened pack) charged to about 70% capacity -
then there has to be some losses due to the mere time on the shelf/ storage -
so it would be very educational to know what they actually have in capacity taken straight out of the pack.

Anyway a discharge before a charge up is actually good for the batteries, it's a kind of "quick" version of the forming charge.

Now that you've gained statistics of your set of eneloops and new charger
it seems that the batteries are from highest to lowest capacities those that were in slots: 2,3,4,1 for convenience I'll just call them by those numbers ie: (explicitly) b2,b3,b4,b1.

The slots seem to be highest to lowest charge in the order - s3, s2, s4, s1

So I would now use this - b1 in s3; b4 in s2; b3 in s4 and b2 in s1; which may balance things out - however this may have very little practical effect - but it's just my OCD

Oh BTW - this might be a very good reference thread:

Maha MH-C9000 SUPPORT / FAQ Thread

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Last edited by UnknownVT; 09-14-2012 at 09:45 AM.

[sadsack]

Nothing wrong with a little OCD,....... my 7 year old Suffers from it, in large quantity's, Unfortunately he gets it from his father. lol

My time is a little tight tonight, but it is my intention to post an image of the unopened eneloop pack including the date. (Funnily enough I can just about make out the date, it's
"2008 07" now that's some serious shelf life).

Are we looking at a discharge of 400mA
Rest period
Then full Charge at 1000mA ------------- if this is correct UnknownVT, let me know and I'll get to work on them tomorrow.

I'll mark the other pack up as "B".
The unopened pack can then be "C".
ttfn
sadsack

p.s. thank you for the link..

[UnknownVT]

My time is a little tight tonight, but it is my intention to post an image of the unopened eneloop pack including the date. (Funnily enough I can just about make out the date, it's
"2008 07" now that's some serious shelf life).

Are we looking at a discharge of 400mA
Rest period
Then full Charge at 1000mA ------------- if this is correct UnknownVT, let me know and I'll get to work on them tomorrow.

Bearing in mind your time is short -
you could literally set the unopened pack eneloops on discharge now, since that takes a long time at 0.2C = 400mA -
can do this unattended, and it doesn't matter if they sit in the charger after they're "Done", the Maha/PowerEX C9000 does not continue to discharge - so there is no harm in letting them sit - then whenever you return to them - the readings will be there for you to record.

But obviously that is dependent on whether you have the time to take photos of the pack before opening.
However that is not strictly necessary -
I believe you

Just to confirm about that "date" is that marked on the pack
or did you manage to make out the marking on the batteries themselves?

The simple "formula" to remember -
charge @ 0.5C where C = capacity marked on battery -
since eneloops are 2000mAh, 0.5C = 0.5x 2000 = 1000mA

standard discharge @ 0.2C = 0.2 x2000 = 400mA

You ought to be pretty well versed in all this by now and don't really need me to confirm anything for you -
if anything I am now learning from your results....
... so there!

[raider]

Okay. I am slightly late to the party and I too have a virgin set of eneloops bought several months back in a fire sale. I am going to do the discharging test at 400mA and report back what i find.....

[UnknownVT]

Okay. I am slightly late to the party and I too have a virgin set of eneloops bought several months back in a fire sale. I am going to do the discharging test at 400mA and report back what i find.....

Very cool! thank you very much - look forward to your results.

Hopefully you can make out the actual manufacture date on the eneloops -
look carefully on the battery outer film casing at different light angles there should be a marking embossed on it -
you probably can find them quickly by feel first (slight roughness) and a magnifying glass probably would help too.
Please see: How to read Eneloop date code.

[sadsack]

Front Rear & Date of Eneloop pack.


Virgin Pack Discharged state: 3H.26min to full discharge.

Slot 1: --------------- 1256 mAh --------------------- 206min 3H.26min --------------- 1.19v

Slot 2: --------------- 1258 mAh --------------------- 208min 3H.28min --------------- 1.19v

Slot 3: --------------- 1264 mAh --------------------- 206min 3H.26min --------------- 1.19v

Slot 4: --------------- 1257 mAh --------------------- 207min 3H.27min --------------- 1.19v

------------------------------------------------------------

Charged State:

Slot 1: ---------------- 1972 mAh ---------------------- 131 min / 2H.11min ------------ 1.44v after 10min -------- 1.44v ------ after 2H extra charge --- 1.44v

Slot 2: ---------------- 2081 mAh ---------------------- 138 min / 2H.18min ------------ 1.46v after 10 min -------- 1.45v ------ after 2H extra charge --- 1.45v

Slot 3: ---------------- 2094 mAh ---------------------- 139 min / 2H.19min ------------ 1.46v after 10 min -------- 1.45v ------ after 2H extra charge --- 1.45v

Slot 4: ---------------- 1880 mAh ---------------------- 125 min / 2H.5min -------------- 1.44v after 10 min -------- 1.44v ----- after 2H extra charge ---- 1.44v



What do you think UnknownVT......

all the best
sadsack

[UnknownVT]

What do you think UnknownVT......

The most educational and beneficial information was the discharge initial remaining capacity of those eneloops -
perhaps you could please confirm the actual battery manufacture date - marked on the actual batteries
as outlined in post #50 and in How to read Eneloop date code.

averaging a pretty consistent capacity of 1260mAh
from a theoretical factory charge of 75% of 1900-2000mAh = 1425-1500mAh
this makes the loss over 4+years to be a mere 12-16% -
this seems like a pretty good retention of charge for such a long period -

As for your charge - those figures (obviously) look very good indeed.

The weakest cell seems like the one in slot 4 for the charge -
if you are concerned in any way -
then put that one cell through another discharge cycle at 0.2C = 400mA record the capacity
rest >1 hour
and charge it up again at 0.5C = 1000mA
- using what appears to be the strongest slot #3.

But those look in good shape to me.

[raider]

Okay. These are my readings.

These readings are from a new unopened Eneloop 2000mAH virgin set. The battery serial shows the string 11-0400. So I think these Eneloops are manufactured Apr 2011. I have labelled the battery C1, C2, C3, and C4. "C" being this is the 3rd pack I have.

After discharging at 400mA, these are the readings shown on the MAHA charger.

Slot 1 - Battery C1 - 1354mAH - 1.23V - 223min
Slot 2 - Battery C2 - 1357mAH - 1.23V - 226min
Slot 3 - Battery C3 - 1359mAH - 1.23V - 223min
Slot 4 - Battery C4 - 1351mAH - 1.23V - 224min

So the battery maintain about 65% of the charge from Apr 2011 to Sept 2012....not too shabby I guess?

[UnknownVT]

readings are from a new unopened Eneloop 2000mAH virgin set. The battery serial shows the string 11-0400. So I think these Eneloops are manufactured Apr 2011.

Yes, very nice - and thank you so much for doing all this.
To have remaining capacity averaging about 1355mAh -
from a theoretical factory charge of 75% of 1900-2000mAh = 1425-1500mAh

That is a retention with only a loss in nearly 1.5 years of only 5-10% -
these are awesome figures -
as were sadsack's above for 4+years.

This shows that eneloops do retain their charge over long periods (years) very well.

allow those to rest for anything >1 hour and charge them up at 0.5C = 1000mA
(should be around 2+hours to "Done" - then allow the batteries to sit in the live charger for an extra 2 hours for the top-up charge to full capacity) -
and they ought to be ready to go -
continue to treat them the way you have been doing
hopefully they'll give you long and reliable service.

BTW - I think you may well have the newer 1500 cycle or generation 2 eneloops (manufactued May/2010 or later)
which are supposed to better than my now older gen 1 versions.

Thank you,

[raider]

Now re. the charging capacity that sadsack has reported.....I could never seem to get that high....

This is the readings from pack B of my eneloops....after charging at 1000mA overnight. These are not virgin sets though....I have been using these sets...

Battery B1 - 1834mAH
Battery B2 - 1921mAH
Battery B3 - 1922mAH
Battery B4 - 1920mAH

Does this mean my batteries are weaker now? I see 1834mAH as the lowest capacity here...

[UnknownVT]

Now re. the charging capacity that sadsack has reported.....I could never seem to get that high.....

Neither have I -
don't forget sadsack's were a virgin pack of eneloops which he fully discharged
and he just treated about the best way one can short of doing a full forming charge (takes a very long time).

Also if your older eneloops were not fully discharged for any reason -
then the total charge may not indicate the real capacity.

Try that at home-
with your own virgin set that you just fully discharged
and see how much you manage.......

Rest assured your batteries look to be in fine shape -
in fact I don't even get your readings - yours weren't that far off sadsack's -
any time you are in doubt - fully charge them
after >1 hour rest - do a discharge at 0.2C = 400mA
and see what the real capacities are -
you have the right tool to do all this.

[raider]

Thanks Vincent.

What should we do to the weaker battery in the same group...for instance I have one 1834mAH battery in an otherwise 19XXmAH group....

[sadsack]

Hi raider,
Did you remember in which slot each battery came from,
If you had the charger directly in front of you, with the power lead coming from the back,

Can we assume that B1 = Slot 1: ect....

If so, you could go through a few set's of older duff batteries which is what I did with unknownVT, and that way you can find out which is the stronger and which is the weaker slot..
For me Slot 4: seems to be the weakest, so UnknownVT said it may be worth changing the batteries around so that the weaker ones get the benefit of being charged in one of the more powerful slots.
If you see what I mean.....

For UnknownVT,
This virgin set from the pack pictured above, State on the side: 08 07TR I've gone through all four and all state the same number and letters.

[raider]

Hi sadsack. I think slot 1 is generally my weakest slot and yes, I always try to put battery 1 into slot 1 and ditto for the other batteries.

I guess I could try to rotate the batteries every now and then....kinda rotating car tyres :-)

[UnknownVT]

Hi raider,
Did you remember in which slot each battery came from
....
For me Slot 4: seems to be the weakest

Way to go sadsack - see you are now knowledgeable enough.

However I thought your slot #1 was the weakest?
from all your figures (other than your most recent one)
- just like raider's and mine.

This virgin set from the pack pictured above, State on the side: 08 07TR I've gone through all four and all state the same number and letters.

The date should be
08 = year = 2008
07 = month = July
which is the same as your package marking.
How to read Eneloop date code

It may seem a bit OCD to check the actual battery markings
when it is much easier to see on the package -
but there is always the possibility that the batteries were made and stored before they were put in the packages -
especially ones with chargers since the chargers must come from a different manufacturing.

all the best with your batteries
and useful, flexible charger/analyser