Maha MH-C9000, the Wizard One Charger (Part 2)

[wptski]

Power Me Up:

Not sure where you came up with the fact that the original version terminated the dicharge at 1V no load but now it's .9V with a load?

A cell will recover when the load is removed, so if it takes down to .9V loaded, what's the no load voltage? Normally over 1V for sure! If the no load voltage is 1V, it may have been taken down to .5, .4, .3 or 0V.

I can't see MAHA making such a mistake like you have stated!

I've tried taking a good ell down so the no load voltage is .9V using a Duratrax ICE, it can't be done, it recovers in less than a second and rises slowly

 

[Anders]

"The MH-C9000 uses 1.00V voltage to terminate discharge, but it is the OFFLINE voltage, which is measured with the current turned off. CBA uses the ONLINE voltage which is measured with the current still on.

You can better match the result if you allow for a 0.05V to 0.10V deviation in the CBA termination voltage (i.e. set it to 0.90 or 0.95V).

William"

https://www.candlepowerforums.com/threads/148404&highlight=CBA

I don't know if this info is old, from 01-13-2007.


Anders

 

[wptski]

"The MH-C9000 uses 1.00V voltage to terminate discharge, but it is the OFFLINE voltage, which is measured with the current turned off. CBA uses the ONLINE voltage which is measured with the current still on.

You can better match the result if you allow for a 0.05V to 0.10V deviation in the CBA termination voltage (i.e. set it to 0.90 or 0.95V).

William"

https://www.candlepowerforums.com/threads/148404&highlight=CBA

I don't know if this info is old, from 01-13-2007.


Anders

Your missing the point too! A cell recovers from a load with increased voltage in a split second, therefore if a no load voltage value was/is used the voltage under load would be much lower and it's highly unlikely that MAHA used this as it may damage the cell.

I don't see any point in measuring voltage on the off pulse during discharge. The CBA, DuraTrax ICE and Triton are all constant current anyway not pulsed.

 

[Power Me Up]

Power Me Up:

Not sure where you came up with the fact that the original version terminated the dicharge at 1V no load but now it's .9V with a load?

From observation of the original version and comparing it to the improved version sitting next to it.

I've got some "crap" cells with high internal resistance that won't discharge in the new C9000 - they will only give a few mAh before it finishes. Take those same cells out and put them in the old C9000 and they'll discharge to close to their rated capacity. The cells themselves are pretty useless since they're not holding their voltage whilst under load.

A cell will recover when the load is removed, so if it takes down to .9V loaded, what's the no load voltage? Normally over 1V for sure! If the no load voltage is 1V, it may have been taken down to .5, .4, .3 or 0V.

Quite possibly for cells with high internal resistance.

For good cells, it doesn't actually make that much difference - e.g. for Eneloops, I get quite similar results on both the old and the new C9000s.

I can't see MAHA making such a mistake like you have stated!

Well, they did!

I've tried taking a good ell down so the no load voltage is .9V using a Duratrax ICE, it can't be done, it recovers in less than a second and rises slowly

Aren't you actually meaning 1.00 Volts no load?

What is the termination point for the Duratrax ICE?

I think that with the old C9000, most of the voltage difference is due to the internal resistance of the cell as well as the resistance between the cell and the contacts - the cell doesn't really have enough time for the voltage to otherwise recover much.

I suspect that the reason that they originally went with measuring the voltage under no load was to eliminate the effects of the contact resistance.

Each method has its problems - the new version actually under reports the voltage that you would otherwise expect with currents below the maximum of 1 Amp - because it's actually measuring the voltage whilst the cell is undergoing a 1 Amp discharge. The 1 Amp discharge current is pulse width modulated to achieve the desired discharge rate. For cells with high internal resistance, it terminates the discharge early because the cells can't maintain 0.90 Volts under a 1 Amp load - even if they're quite capable of handling a 100 mA discharge.

 

[wptski]

From observation of the original version and comparing it to the improved version sitting next to it.

I've got some "crap" cells with high internal resistance that won't discharge in the new C9000 - they will only give a few mAh before it finishes. Take those same cells out and put them in the old C9000 and they'll discharge to close to their rated capacity. The cells themselves are pretty useless since they're not holding their voltage whilst under load.

Quite possibly for cells with high internal resistance.

For good cells, it doesn't actually make that much difference - e.g. for Eneloops, I get quite similar results on both the old and the new C9000s.

Well, they did!

Aren't you actually meaning 1.00 Volts no load?

What is the termination point for the Duratrax ICE?

I think that with the old C9000, most of the voltage difference is due to the internal resistance of the cell as well as the resistance between the cell and the contacts - the cell doesn't really have enough time for the voltage to otherwise recover much.

I suspect that the reason that they originally went with measuring the voltage under no load was to eliminate the effects of the contact resistance.

Each method has its problems - the new version actually under reports the voltage that you would otherwise expect with currents below the maximum of 1 Amp - because it's actually measuring the voltage whilst the cell is undergoing a 1 Amp discharge. The 1 Amp discharge current is pulse width modulated to achieve the desired discharge rate. For cells with high internal resistance, it terminates the discharge early because the cells can't maintain 0.90 Volts under a 1 Amp load - even if they're quite capable of handling a 100 mA discharge.

It's not cells with a high internal impedance either and furthermore, it's Ni-MH, Ni-CD or Li-Ion too, all cells voltage rise when the load is removed.

What's the voltage of cells after discharging on either of your chargers? Over 1V I'm sure! How can that be if you say one discharges to 1V no load? Quit watching the screen, I think that your seeing things! Connect a DMM to your original 1V no load charger, even though it's pulsed, you'll be able to see very very low voltage.

The ICE can be set to discharge to .1-1.1V. At the lowest settong of .1A going down to .1V, a Ni-MH will rise to over .9V when the load is removed.

Did I mean 1V no load? I think that I covered that but I'll say again, you can't really even discharge a cell to .9V no load because the cell voltage always rises to above .9V when the load is removed.

 

[Power Me Up]

It's not cells with a high internal impedance either and furthermore, it's Ni-MH, Ni-CD or Li-Ion too, all cells voltage rise when the load is removed.

What's the voltage of cells after discharging on either of your chargers? Over 1V I'm sure! How can that be if you say one discharges to 1V no load?

It does take time for the voltage of a cell to fully recover after the load has been removed - it's not a totally instantaneous thing.

When you remove the load from a cell, the voltage will recover in 2 stages.

The first is an instantaneous jump because there is no longer a voltage drop due to the current flowing through the internal resistance of the cell (and any external contact resistance, wire resistance, etc)

The second is a more gradual rise as the ions redistribute themselves within the electrolyte. This can take a few seconds which you can prove to yourself by taking a discharged cell, put a CRO across it and then connect and disconnect a load to it.

Quit watching the screen, I think that your seeing things!

So what is it that you think I'm seeing?

Connect a DMM to your original 1V no load charger, even though it's pulsed, you'll be able to see very very low voltage.

Depending on the cell, yes, the voltage will be getting significantly below 1 Volt whilst it is under load.

The ICE can be set to discharge to .1-1.1V. At the lowest settong of .1A going down to .1V, a Ni-MH will rise to over .9V when the load is removed.

Yes, but how long does it take for the voltage to recover?

Did I mean 1V no load? I think that I covered that but I'll say again, you can't really even discharge a cell to .9V no load because the cell voltage always rises to above .9V when the load is removed.

I never said that any of the chargers discharge to 0.9 Volts no load. The first version discharges to 1.00 Volts no load. The second version discharges to 0.90 Volts under load.

If you don't want to take my word for it, you could just take the word of William Chueh in the other thread linked to by Anders. William Chueh is a respresentative of Maha/Powerex - the manufacturer of the Maha MH-C9000 Charger-Analyzer.

If you still don't want to believe us, can you please explain why a cell with high internal resistance that refuses to discharge on the new version of the C9000 will discharge fine on the old C9000?

 

[bcwang]

It'll be interesting to see if anyone else gets a new unit with that code on it.

Do you know how to reproduce the repeating digits bug? Could you have a go and see if the replacement unit still has that bug?

I'll try it out right now to see if it occurs.

 

[wptski]

It does take time for the voltage of a cell to fully recover after the load has been removed - it's not a totally instantaneous thing.

When you remove the load from a cell, the voltage will recover in 2 stages.

The first is an instantaneous jump because there is no longer a voltage drop due to the current flowing through the internal resistance of the cell (and any external contact resistance, wire resistance, etc)

The second is a more gradual rise as the ions redistribute themselves within the electrolyte. This can take a few seconds which you can prove to yourself by taking a discharged cell, put a CRO across it and then connect and disconnect a load to it.

So what is it that you think I'm seeing?

Depending on the cell, yes, the voltage will be getting significantly below 1 Volt whilst it is under load.

Yes, but how long does it take for the voltage to recover?

I never said that any of the chargers discharge to 0.9 Volts no load. The first version discharges to 1.00 Volts no load. The second version discharges to 0.90 Volts under load.

If you don't want to take my word for it, you could just take the word of William Chueh in the other thread linked to by Anders. William Chueh is a respresentative of Maha/Powerex - the manufacturer of the Maha MH-C9000 Charger-Analyzer.

If you still don't want to believe us, can you please explain why a cell with high internal resistance that refuses to discharge on the new version of the C9000 will discharge fine on the old C9000?

I've never measured the exact recovery time of a Ni-MH cell but users of Li-Ion cells were saying that a light shut off, got dim, etc. and when they removed the cell(s) they measured this or that. I do remember a .6 second recovery time for Li-Ion, so by the time you remove the cell(s) grab your meter, well!

You didn't say .9V no load, I did. What I'm trying to point out is that I "tried" to discharge to .9V no load and it can't be done because a healty cell will always recover to over .9V as soon as the load is removed.

I've talked to William Chueh going back ten years about my first MAHA C210 charger. Either he is mistaken or the pulse rate is faster than the no load recovery time, if not, it could damage the cell.

I ask one more time. What does a cell's voltage show on your original unit right after a discharge cycle finishes??

This is also a also a major change in the operation that I never heard about. Of course I don't spend that much time here anymore too!

I can't explain differences in operation with different units with high impedance cells. They are crap cells, recycle them!

Are you actually seeing a .9V discharge value on one and 1V on the other while watching or are you going by what William Chueh said?

EDIT: Discharging a single cell at 500ma showed .9V and in the cycle period of the display show it recovered to 1.09V the next time.

 

[Power Me Up]

I've never measured the exact recovery time of a Ni-MH cell but users of Li-Ion cells were saying that a light shut off, got dim, etc. and when they removed the cell(s) they measured this or that. I do remember a .6 second recovery time for Li-Ion, so by the time you remove the cell(s) grab your meter, well!

It takes a lot less time for the C9000 to remove the load and measure the voltage than it does to remove a cell from a flashlight!

You didn't say .9V no load, I did. What I'm trying to point out is that I "tried" to discharge to .9V no load and it can't be done because a healty cell will always recover to over .9V as soon as the load is removed.

Right... But since I never said 0.90 Volts under load, I fail to see the relevance!

I've talked to William Chueh going back ten years about my first MAHA C210 charger. Either he is mistaken or the pulse rate is faster than the no load recovery time, if not, it could damage the cell.

I'd say that the time between removing the load and measuring the voltage is significantly less than the recovery time for the cell.

I ask one more time. What does a cell's voltage show on your original unit right after a discharge cycle finishes??

Sorry - I don't recall you asking that.

On both units, the voltage does rise after the discharge has completed. I can't recall exact numbers at the moment and my old C9000 is currently doing a break in cycle at the moment. I can do a test later today and report back actual numbers if you like?

This is also a also a major change in the operation that I never heard about. Of course I don't spend that much time here anymore too!

I don't think this is something that will make much difference to most people, so not too many people would have noticed...

I can't explain differences in operation with different units with high impedance cells. They are crap cells, recycle them!

Actually, some of them are 2500 Energizers - I'm waiting for them to come out with LSD cells, so that I might be able to get them instead when I return them.

Are you actually seeing a .9V discharge value on one and 1V on the other while watching or are you going by what William Chueh said?

Yes - I'm seeing the discharges terminate at 1.00 Volts on the old C9000 and 0.90 Volts on the new C9000.

 

[TorchBoy]

Bill, what Power Me Up is explaining is accurate. That is the way the old and new versions work.

And since you've explained it so well, Power Me Up, I don't think I need to add anything here at all. :thumbsup:

 

[wptski]

It takes a lot less time for the C9000 to remove the load and measure the voltage than it does to remove a cell from a flashlight!

Right... But since I never said 0.90 Volts under load, I fail to see the relevance!

I'd say that the time between removing the load and measuring the voltage is significantly less than the recovery time for the cell.

Sorry - I don't recall you asking that.

On both units, the voltage does rise after the discharge has completed. I can't recall exact numbers at the moment and my old C9000 is currently doing a break in cycle at the moment. I can do a test later today and report back actual numbers if you like?

I don't think this is something that will make much difference to most people, so not too many people would have noticed...

Actually, some of them are 2500 Energizers - I'm waiting for them to come out with LSD cells, so that I might be able to get them instead when I return them.

Yes - I'm seeing the discharges terminate at 1.00 Volts on the old C9000 and 0.90 Volts on the new C9000.

Wether it's .9V or 1V, it doesn't matter, a cell recovers and that's what makes it relevant. I could have been using 1V and still have the same results.

Energizer 2500 are crap cells, I have four that won't hold a charge also!

If somebody stated 1V no load, it should really mean that, not 1V on the OFF cycle. If the cell hasn't had a chance to recover then it isn't a no load condition fully!

 

[Power Me Up]

If somebody stated 1V no load, it should really mean that, not 1V on the OFF cycle. If the cell hasn't had a chance to recover then it isn't a no load condition fully!

William Chueh had worded things a bit differently to me:

The MH-C9000 uses 1.00V voltage to terminate discharge, but it is the OFFLINE voltage, which is measured with the current turned off. CBA uses the ONLINE voltage which is measured with the current still on.

Were his words also confusing?

To me "no load" just says that the load isn't connected - it doesn't say how long the load is actually disconnected for...

Anyway... I think everyone is now clear on this topic?

 

[wptski]

William Chueh had worded things a bit differently to me:



Were his words also confusing?

To me "no load" just says that the load isn't connected - it doesn't say how long the load is actually disconnected for...

Anyway... I think everyone is now clear on this topic?

The topic isn't clear but still fuzzy as many questions about the C9000!

His statement is too brief If the pulse rate on discharge is the same as on charging it was just under 2 seconds, so it measured as the cell's voltage was still rising and probably not very accurate. That's probably why it was charged to the standard loaded voltage.

Unless one can figure out on their own, how it works, MAHA isn't going to tell you exactly how it works! Many questions were posted here since the C9000 was released in 12/05 but MAHA didn't answer the ones that were never figured out. Just lots of "IMHO" now!

 

[Artie Choke]

I just bought one direct from Maha and it has the 0G0IA code. Right now I'm running the refresh/analyze mode on some 2300 mah Energizers. Hopefully they'll hold a charge for longer than a week - doh! I had some really old PowerEx batteries from Maha and two of them showed HIGH, so I'm tossing those.

It's independent bays really make it nice if you want to charge different brand or capacity batteries at the same time.

 

[bcwang]

Ok, I tested 0G0IA for the repeating digit bug but I don't see it. I'm not sure if I did it right since I've never seen it, but what I did was

1. Insert 4 cells, put them all into default ch/disch and 3 cycles
2. go to slot 1, push down arrow until cycle 1, when it shows capacity it said something like 1865mah, so with the bug would it have shown 1818?
3. I also looked at every cycle of every slot and nothing looked like the repeating digit bug.

One strange thing I noticed is after running this charger through some tenergy 2500 and an energizer 2500 I have, the capacity has been showing 16xx to 18xx mah. I don't remember the capacities of these cells being so low when tested in the past. I'm going to have to try out some fresh batteries to see if it's the charger or if those batteries really already went bad even with so little usage. I'll probably also test the same batteries in my bc900 to see if it gives similar readings now.

 

[snakebite]

got both of mine replaced a while back due to missed termination.
got 0g0d01
but now one has a bad slot button and the other one is now developing a flaky slot button.
anyone else?

 

[BrianChan]

Hi Power Me Up,

I usually charge all my cells at 2A with my OGOE02, am I correct to say that the old version gives a more complete charge at this rate compared to the improved version, which requires a 2 hour top-off charge before going into trickle charge?

From what I've read the issue with old versions was missed termination at low charge rates, there were no termination issues with a 2A charge rate. With my preference to charge at 2A this would not be an issue to me at all. If this is true I guess I would be happy to exchange my new 0G0E02 version for an old one with someone here.

 

[Power Me Up]

Hi Power Me Up,

I usually charge all my cells at 2A with my OGOE02, am I correct to say that the old version gives a more complete charge at this rate compared to the improved version, which requires a 2 hour top-off charge before going into trickle charge?

From what I've read the issue with old versions was missed termination at low charge rates, there were no termination issues with a 2A charge rate. With my preference to charge at 2A this would not be an issue to me at all. If this is true I guess I would be happy to exchange my new 0G0E02 version for an old one with someone here.

After the 2 hour top-off charge, your cells should be pretty close to their full capacity.

If you're charging at 2A because you're in a hurry and you want to pull them as soon as the charger says "Done" then yes, the original version will give you a more complete charge.

 

[servaas]

...the original version will give you a more complete charge.

Has someone tested this, or is it because the 0Fxxxx models report a higher capacity than the 0Gxxxx models on the same batteries?

 

[Power Me Up]

Has someone tested this, or is it because the 0Fxxxx models report a higher capacity than the 0Gxxxx models on the same batteries?

You're misquoting me by leaving out the majority of that sentence...

I've got both 0F and 0G units, so I'll do some testing to compare both charging and discharging on both types and report back.