Just recieved my Maha MH C9000 today! But I need some beginners help......

[roadwarrior]

Sounds good. Kind of curious what my scanner's mAh cut off is, so I will probably run a discharge out of curiosity.

Thanks for detailed answer!

 

[MidnightDistortions]

Usually the cells would only have about 10-25% left if the cut off point is 0.9 volts, if it's a high drain device. Make sure you choose 100mA to discharge the cells, but if they show done within several seconds or minutes they were most likely depleted to begin with.

 

[roadwarrior]

Usually the cells would only have about 10-25% left if the cut off point is 0.9 volts, if it's a high drain device. Make sure you choose 100mA to discharge the cells, but if they show done within several seconds or minutes they were most likely depleted to begin with.

Glad I read this right after I started the discharge cycle....I had selected 600mAh based of the cell's rated capacity....after I read this I quickly realized, I was not dealing with a full cell, so the 100mAh rate made more sense. At least that is why I think you said that.....

 

[Phlogiston]

To determine the theoretical maximum you might get out of the cells if you left them in the scanner, consider the cell capacity divided by the number of hours until the scanner gives you a low battery warning.

For example, if you get 9 hours to low battery on 2200mAh cells, 2200 divided by 9 is about 244 mA. In that case, I'd pick a 200mA discharge rate to account for the fact that the cells aren't fully discharged and the scanner would actually be drawing a bit less current than the 244mA approximation.

 

[roadwarrior]

I ended up discharging at 100mAh and got the following discharged capacities:
1-18
2-164
3-141
4-135

I want to say they were being discharged at 600mAh for maybe 10 or so mintues prior to me reading Midnight's post and changing to the lower rate.

 

[Phlogiston]

600mA for 10 minutes is 100mAh, so you can add 100 to each of those capacities.

That means your scanner's low battery warning is kicking in when the cells are down to about 10% charge remaining. It looks like the low battery warning is well-optimised for NiMH cells.

 

[roadwarrior]

Sounds good!

Thanks for the feedback. :thanks:

 

[roadwarrior]

The only thing that has me scratching my head was battery #1 in slot 1.....18mAh? Kind a bit off from the others....anything wrong or something I should be concerned about with that one?

These were Duracell 2500mAh Ion Core AAs.

 

[roadwarrior]

Deleted

 

[Rosoku Chikara]

The only thing that has me scratching my head was battery #1 in slot 1.....18mAh? Kind a bit off from the others....anything wrong or something I should be concerned about with that one?...<snip>

There has been considerably discussion on this forum about Slot 1 of the C9000. It does tend to consistently give different (lower?) readings than might otherwise be expected. I don't think anyone has ever successfully explained why.

Remember, however, that this device is far from being a scientific instrument. It costs only tens of dollars... not the hundreds, or more likely thousands, you would have to spend to get something "truly" accurate. But, please believe me, I am certain that you will find it accurate enough for all your household NiMH cell diagnostic and charging needs. I did the same thing in the beginning, but be wary of "over thinking" some of these issues.

The other thing which I want to stress is that, in my opinion, all the numbers shown in the display readout, after performing any operation (except Refresh & Analyze) should be considered to be only approximate indications. They are still useful, but don't get too worked up about them. Use the Refresh & Analyze function to check your cell's capacity (which is the key indicator of cell condition that you should be most concerned about) and if it still has good capacity, you have a good cell. If all four cells have the same capacities (within about +/- 5%) use them together as a "matched set" of four. If some of your "matched sets" have a tighter margin (say +/- 2 or less) they are probably a bit "better" but only slightly... and not really enough to worry about in the real world.

There was so much talk about Slot 1, that I once performed a fairly detailed analysis. I took 4 cells and sequenced them through all 4 slots, such that the capacity of each cell was tested in each slot, multiple times. (Just a "tad" OCD?) It took forever, and my conclusion was that there does appear to be something slightly "odd" about Slot 1, but the difference is so minor that it is ultimately lost in the "noise" of random variations. (In other words, it is beyond the limit of the C9000's ability to measure capacity accurately.)

So, what I say is: "Stop worrying, and just use the dang thing. I am pretty certain that it is best NiMH charger you can own. And, if not, it is certainly up there with the best."

 

[roadwarrior]

Do you guys agree with Maha's recommended charging currents?

2700mAh Charge: 1300mA Discharge: 700mA
2650mAh Charge: 1300mA Discharge: 700mA
2500mAh Charge: 1200mA Discharge: 600mA
2300mAh Charge: 1100mA Discharge: 600mA
2200mAh Charge: 1100mA Discharge: 600mA
2100mAh Charge: 1000mA Discharge: 500mA
2000mAh Charge: 1000mA Discharge: 500mA
1000mAh Charge: 500mA Discharge: 200mA
900mAh Charge: 400mA Discharge: 200mA
850mAh Charge: 400mA Discharge: 200mA

The reason I ask, is my batteries were very warm; almost hot at DONE. They were the previously posted about Duracell 2500mAh AAs....Wondering if a lower rate would be better for them? I used the 1200mAh recommended rate....

If there is one thing I have learned from you guys is; heat is "no bueno" for NiMH batteries!

This was my first straight Charge mode attempt with any of my quads and the first one on the Duracells. They were charged from a totally discharged state. (I fully discharged them because I was curious of what my scanner's cutoff mAh is at it's programmed low-battery alert.)

My other two quads; Energizer 2300mAh have only been charged twice via a Refresh/Analyze and a CYCLE X3. CORUN was charged once via a Refresh/Analyze.

These were the DONE charging capacities on the Duracells:


1-2510
2-2786
3-2811
4-2628

I hope I am making sense to you guys.... :sigh:

 

[roadwarrior]

So, what I say is: "Stop worrying, and just use the dang thing. I am pretty certain that it is best NiMH charger you can own. And, if not, it is certainly up there with the best."

Thanks for the reassuring feedback.....kind of weird for one OCD guy to tell another OCD guy not to worry though...

P.S.

Posted another "I am freaking out" post before I read this one, if you care to tackle it.

 

[Rosoku Chikara]

Do you guys agree with Maha's recommended charging currents?

I can't see me (or anyone else?) arguing too strongly against what Maha recommends... As I have already pointed out, I "made the mistake" of using lower current, but so far that seems to work fine too.

The reason I ask, is my batteries were very warm; almost hot at DONE. They were the previously posted about Duracell 2500mAh AAs....Wondering if a lower rate would be better for them? I used the 1200mAh recommended rate....

I think "very warm" and "almost hot" are far too subjective. I think you will need to provide some actual temperature readings before anyone can comment intelligently. My guess is that the heat level you are sensing with your fingers is fine. But, if you really want to know, figure out some way to get a real temperature reading.

These were the DONE charging capacities on the Duracells:


1-2510
2-2786
3-2811
4-2628

On the left, are the "Done" capacities for 4 Eneloop "Black" cells that were discharged straight out of the package, broken-in, discharged again, then analyzed:

ENELOOP PRO		"DURALOOP" ION CORE
ANALYZE	"Accentuated"	Variance	ANALYZE	"Accentuated"	Variance
2430 mAh	-107%	-20 mAh	2510 mAh	150%	10 mAh
2436 mAh	-56%	-14 mAh	2786 mAh	2508%	286 mAh
2448 mAh	47%	-2 mAh	2811 mAh	2721%	311 mAh
2456 mAh	115%	6 mAh	2628 mAh	1158%	128 mAh
	Avg. Variance	-8 mAh		Avg. Variance	184 mAh
	Standard Dev.	12 mAh		Standard Dev.	141 mAh

Your Duraloops are on the right.

The Variance and Average Variance is based on the cells' rated capacity. The "Accentuated" % number is based on a simple formula that uses Avg. Variance and Standard Deviation to make the differences far more obvious. (I was starting to go blind trying to decide which cells in a batch of 16 cells should be grouped together in order to create the best matched sets.)

At a glance, it appears that your Duraloops show far more variance than what is typical for Eneloop Pros purchased in Japan. (These four Pros were selected at random, and they are typical "straight out of the package" readings for all Eneloop Pros that I have purchased.)

 

[MidnightDistortions]

The only thing that has me scratching my head was battery #1 in slot 1.....18mAh? Kind a bit off from the others....anything wrong or something I should be concerned about with that one?

These were Duracell 2500mAh Ion Core AAs.

I don't think there's anything to worry about. If anything it might have been the radio discharging that battery slightly more or it could be that it had a bit less charge, i'd probably keep an eye on that battery and maybe let it trickle charge for an extra hour or so the next time you charge it.

 

[roadwarrior]

I can't see me (or anyone else?) arguing too strongly against what Maha recommends... As I have already pointed out, I "made the mistake" of using lower current, but so far that seems to work fine too.



I think "very warm" and "almost hot" are far too subjective. I think you will need to provide some actual temperature readings before anyone can comment intelligently. My guess is that the heat level you are sensing with your fingers is fine. But, if you really want to know, figure out some way to get a real temperature reading.



On the left, are the "Done" capacities for 4 Eneloop "Black" cells that were discharged straight out of the package, broken-in, discharged again, then analyzed:

ENELOOP PRO		"DURALOOP" ION CORE
ANALYZE	"Accentuated"	Variance	ANALYZE	"Accentuated"	Variance
2430 mAh	-107%	-20 mAh	2510 mAh	150%	10 mAh
2436 mAh	-56%	-14 mAh	2786 mAh	2508%	286 mAh
2448 mAh	47%	-2 mAh	2811 mAh	2721%	311 mAh
2456 mAh	115%	6 mAh	2628 mAh	1158%	128 mAh
	Avg. Variance	-8 mAh		Avg. Variance	184 mAh
	Standard Dev.	12 mAh		Standard Dev.	141 mAh

Your Duraloops are on the right.

The Variance and Average Variance is based on the cells' rated capacity. The "Accentuated" % number is based on a simple formula that uses Avg. Variance and Standard Deviation to make the differences far more obvious. (I was starting to go blind trying to decide which cells in a batch of 16 cells should be grouped together in order to create the best matched sets.)

At a glance, it appears that your Duraloops show far more variance than what is typical for Eneloop Pros purchased in Japan. (These four Pros were selected at random, and they are typical "straight out of the package" readings for all Eneloop Pros that I have purchased.)

Yeah, I don't know what to make of such high variance. The cells do say "HR6/NiMH 1.2 V/2500mAh, standard charge/charge standard 250mA for/pendant 16 h/ Made in Japan" on them.

I'll just keep using them and see what happens down the road, keeping an ad hoc log right now on them and the others.

Thanks for the insight.

 

[roadwarrior]

I don't think there's anything to worry about. If anything it might have been the radio discharging that battery slightly more or it could be that it had a bit less charge, i'd probably keep an eye on that battery and maybe let it trickle charge for an extra hour or so the next time you charge it.

Will do.

 

[Rosoku Chikara]

Yeah, I don't know what to make of such high variance. The cells do say "HR6/NiMH 1.2 V/2500mAh, standard charge/charge standard 250mA for/pendant 16 h/ Made in Japan" on them.

I'll just keep using them and see what happens down the road, keeping an ad hoc log right now on them and the others.

Thanks for the insight.

I wouldn't worry about them. They appear to be good cells with excellent capacity. I am pretty sure that I have "gone overboard" with my attempts to match cells.

As I understand it, high variation is really only a true issue in devices/applications where one (or more) cells can get fully depleted while the others are still attempting to provide current.

Your scanner appears to be a "smart device" that tells you to stop using the cells (and it tells you to "stop," well before any of the cells are fully depleted). Therefore, according to my understanding, the level of variation that your cells are showing should never present any problems in that device.

But, as you say, keep some kind of a log, and if you notice that the performance of that one cell continues to get worse, it may mean that there happens to be something a bit wrong with that cell. Even then, you can certainly keep using it, but I would probably relegate it to some other application such as a single AA cell flashlight.

 

[roadwarrior]

I wouldn't worry about them. They appear to be good cells with excellent capacity. I am pretty sure that I have "gone overboard" with my attempts to match cells.

As I understand it, high variation is really only a true issue in devices/applications where one (or more) cells can get fully depleted while the others are still attempting to provide current.

Your scanner appears to be a "smart device" that tells you to stop using the cells (and it tells you to "stop," well before any of the cells are fully depleted). Therefore, according to my understanding, the level of variation that your cells are showing should never present any problems in that device.

But, as you say, keep some kind of a log, and if you notice that the performance of that one cell continues to get worse, it may mean that there happens to be something a bit wrong with that cell. Even then, you can certainly keep using it, but I would probably relegate it to some other application such as a single AA cell flashlight.

Will do! :thanks: