Maha MH-C9000 SUPPORT / FAQ - continuation

[czAtlantis]

I was curious if maha measures same capacity when powered from different voltages - I tested freshly opened pack of eneloops lite (because I know when I discharge them all 4 together their capacities are exactly the same +-5mAh) and discharged two at 14V input and two at 11V input - results were exactly same - within 5mAh.

Another test I performed - I again used freshly opened pack of eneloops (in this case AAA lite) and I tested if charging slots are independent - So in slot 1 was measured battery and in other slots were ohers battereis charging/discharging and there were some differences:
first battery (solo) - 397mAh
second battery (other slots charging):407mAh
third battery (other slots discharging):393mAh
fourth battery (other slots charging again) :407mAh

So charging bays are slightly affected by each other but it is not very significant. Charger and batteries were cooled by fan to exclude temperature effect.

[march.brown]

Probably a silly question , but is the Powerex C9000 charger the same as the Maha C9000 ? ... If not , what are the differences.

The ones advertised as the Maha are more expensive than the ones advertised as Powerex.
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[czAtlantis]

I believe Powerex is company and Maha is product...anyway mine says "Powerex" on the front and "Maha" on the back :-)

[ferdz]

Probably a silly question , but is the Powerex C9000 charger the same as the Maha C9000 ? ... If not , what are the differences.

The ones advertised as the Maha are more expensive than the ones advertised as Powerex.
.

AFAIK, they are one and the same. The full name of the the product is Maha Powerex MH-C9000 WizardOne Charger-Analyzer. Maha is the name of the company (Maha Energy Corporation) and Powerex is one of its trademark brands/products. Maybe the more expensive ones you are seeing are those bundled with the 4x AA batteries (either a Powerex 2700mAh or Imedion 2400mAh).

[45/70]

Yeah, although I belive it's actually the other way round. Maha Energy Corporation is the actual company, and Powerex is the product line. Anyway, yes my C9000's all have a Powerex badge on the front.

Dave

[march.brown]

Hi guys , thanks for all the help , I have just sent for one.

It was on Amazon UK , though it is apparently being sold be Mertrado Gmbh (Dandyshop) ... Not certain how long it will take to arrive in the UK from Germany though ... I originally intended to spend up to about £20 ('ish) , but this charger cost £39 ... About double what I originally intended.

I won't be able to tell "The Lady of the House" as she already thinks that three chargers are "two too many" ... But although one of them already has a discharge facility , none of them can calculate the battery capacity ... I want to put the cells in batches according to measured capacity ... I need a couple of spare matched sets of six AA's for my Wifes "Pure" radio ... Hence my vast expenditure (double the original) ... I know that is a pretty feeble excuse , but it's the best reason that I can think of at the moment and it IS for my Wifes radio ... I only bought this charger for HER needs !

74 years old and that is the best excuse I can think of !

I just hope the user manual is in English since the charger is coming from Germany !
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[apagogeas]

...I just hope the user manual is in English since the charger is coming from Germany !

Even if it was Chinese, you shouldn't worry about that. Everything you need to know and many more "secrets" are in CPF.

[AlphaZen]

Manual

[ferdz]

I'm not sure if I missed it or anything, but is there a way to determine the capacity of the battery without using R&A? Like plugging it in then pressing some buttons and it will show the status of the battery.

[czAtlantis]

You can't measure capacity without discharging battery - it is not like voltage which can be measured in one second...

[SilverFox]

Hello Ferdz,

Welcome to CPF.

The short answer is no.

In order to determine capacity a discharge is needed. You can put a cell into the charger and select discharge and then come back some time later and see how much was left in the cell. But you end up with a discharged cell.

The ZTS tester uses a look up table. They apply a load to the cell and compare the voltage of the cell to a look up table that they have put together by testing a variety of cells. Based upon their table, you can get some idea of how much is left in the cell. Some chargers also offer something like that giving results like charged, half charged, and discharged. The ZTS gives results as 10%, 20%, 40%, 60%, 80%, and 100%. If your cell matches the cells used to develop their look up table, you get reasonable results.

It is possible to put a cell into the Maha charger and then look at the voltage of the cell under a discharge load. If you have some experience with your cells and your lights, you may be able to get an idea of how much is left in the cell by just reviewing the voltage under load show by the charger during discharge.

Tom

[ferdz]

Thanks very much Tom & czAtlantis!

I initially did a standard discharge on my old AA batteries (labels already peeled off, most likely a 2x Sony 2500mAh or 2700mAh and 2x EcoMax 2100mAh (an Eneloop clone)), but was not able to record the results. If I remember correctly, the results were around 1000-1200mAh so I was a bit surprised if I did it correctly as I thought that capacity should be on the low side as it's supposed to discharge it. So, I put them back again for another discharge and in about 1-2 minutes it was already done and the readings were 12, 10, 2, 10 respectively.

They are now almost done with with their break-in and I'm logging the results for tracking/reference.

I'm just noticing that Slot #1 of my charger is about 100mAh lower than its pair in Slot #2, while Slots #3 and #4 is just +/-15 with each other. Will still be doing another set of Break-in for 2 pairs of Eneloops after this one.

[march.brown]

I have not yet received my C9000 charger, but I have a query that needs to be addressed before I start using it.

Assume that all my cells are at slightly different states of charge , with some fairly fully charged and others in a lower state of charge ... I want to know their proper mAh capacity.

Do I first of all discharge all the cells to 0.9 volts , then charge and discharge them to find the capacity , then charge them again.

OR

Do I charge them fully first , hoping that the charger will take into account the fact that all the cells are in different states of charge , then discharge and re-charge them to find the proper mAh capacity.

At the moment I stick my used or partly used cells on the charger and can see by the number of LCD segments , the state of charge of individual cells ... I now want to put my AA and AAA batteries into batches where the capacities are fairly evenly matched ... I will be using six AA's in Fameart C-cell adaptors in my Wifes "Pure" radio ... The radio takes 190mA whilst playing at a reasonable volume , so in theory my Eneloops should last ten hours ... If all the cells are nearly identical in capacity , they should all start to die at about the same time and the Radio would stop working ... No harm should come to individual cells as they would all (hopefully) be at the same (low) voltage ... If one (only) cell died in the radio first and all the others were still good , then that cell would be reverse charged and might be seriously damaged to the extent that it's capacity would be seriously reduced ... Hence the idea that closely matching cells should be used.

I'm sure that I will eventually get the hang of the new charger , but it doesn't look as though it is a matter of sticking the cells in and powering up the charger (like I do at the moment).
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[czAtlantis]

Charging bays are independent - it means you can put 80% charged cell in bay 1, 10%charged cell in bay2 and even run different programs on every cell (charge, discharge, break-in..)
So if you put your mismatched batteries in charger and run refresh and analyze, some cells (charged ones) will just finish sooner because first phase (charging) will be completed quickly.

But if you want to use Break-in mode you have to discharge all cells first.

[march.brown]

Charging bays are independent - it means you can put 80% charged cell in bay 1, 10%charged cell in bay2 and even run different programs on every cell (charge, discharge, break-in..)
So if you put your mismatched batteries in charger and run refresh and analyze, some cells (charged ones) will just finish sooner because first phase (charging) will be completed quickly.

But if you want to use Break-in mode you have to discharge all cells first.

Thank you for the information czAtlantis.

Thank you AlphaZen for the manual in English ... I have printed it off and will try to memorise it all before the charger arrives from Germany.

I will have to scan through this thread again to see if I have missed anything.

It looks as though it is going to take a long time to check all my AA's and AAA's and get them sorted into "similar capacity" groups ... I will have to number each cell with indelible ink to keep track of everything ...

Previously I just took the required number of batteries out of my stock as required without knowing their exact capacity ... I don't suppose that it mattered too much with single or double cell applications , but with my four and six cell radios it looks as though it is necessary to avoid reverse charging damage to weaker cells.

Still , it gives me something to do when "her indoors" is watching her soaps !

Again , thanks for everyones input.
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[edpmis02]

Any issues with using the charger off a UPS (running off battery power) or car 12v->120v adapter with a stepped sine wave?

[march.brown]

Another few possibly silly questions !

In the specifications for the C9000 , it says "Topoff Charging current 100mA" ... Does this mean that when the "DONE" sign appears , the charge drops to 100mA for a period of time ? ... If so how long ? ... When "DONE" appears , there is no charging current displayed , only time , volts and mAh ... How can I see any charging/topoff current.

Also , in the specifications it says "Maintenance Charging Current 10mA" ... Does this mean that after the Topoff finishes , the charger drops down to 10mA for as long as the batteries are on charge ? ... How do we know that the current is down to 10mA ?

If a cell has previously been fully (?) charged in another charger , will the cell suffer from having one amp pushed in by the C9000 ?

Trouble is that in my other three chargers , I just bung the cells in and leave them till the LED says that they are ready ... I do check the temperature of the batteries now and again (by hand) , just in case.

If the C9000 tells me that the cells are charged and I then remove and immediately replace them , Will I then be able to see the mAh charge that has been put in this second time ? ... If I repeat this a few times till no more charge (mAh approaches zero) is displayed , will the cells be totally fully charged ? ... This would be quicker than leaving them in the charger to "Topoff" ... How harmful would it be to my Eneloops.

Do you leave the cells on charge till they reach a particular voltage ? ... Three of mine are showing 1.47V and one (slot two) is showing 1.46V.

I'm sure I will eventually get to trust the C9000 , but I just like to know all the facts !

p.s. All slots are now reading 1.47V.
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[Yamabushi]

In the specifications for the C9000 , it says "Topoff Charging current 100mA" ... Does this mean that when the "DONE" sign appears , the charge drops to 100mA for a period of time ? ... If so how long ? ... When "DONE" appears , there is no charging current displayed , only time , volts and mAh ... How can I see any charging/topoff current.

Topoff runs 2 hours. You get no information regarding progress or current (an irritating flaw in the UI).

Also , in the specifications it says "Maintenance Charging Current 10mA" ... Does this mean that after the Topoff finishes , the charger drops down to 10mA for as long as the batteries are on charge ? ... How do we know that the current is down to 10mA ?

Yes. Again, no information is displayed.

If a cell has previously been fully (?) charged in another charger , will the cell suffer from having one amp pushed in by the C9000 ?

No. If it's fully charged, it should terminate almost immediately. The exception is the break-in mode which charges for 16 hours; I always discharge fully before starting break-in.

If the C9000 tells me that the cells are charged and I then remove and immediately replace them , Will I then be able to see the mAh charge that has been put in this second time ? ... If I repeat this a few times till no more charge (mAh approaches zero) is displayed , will the cells be totally fully charged ? ... This would be quicker than leaving them in the charger to "Topoff" ... How harmful would it be to my Eneloops.

You'll see the information but I think it will terminate almost immediately each time and you won't get the same capcity result as Topoff.

Do you leave the cells on charge till they reach a particular voltage ? ... Three of mine are showing 1.47V and one (slot two) is showing 1.46V.

I let the charger terminate and topoff by itself.

[SilverFox]

Hello March.brown,

The charge termination method for the C9000 is -dv, peak voltage, or time. Many times the charge will terminate on peak voltage. Peak voltage termination is 1.47 volts.

Depending on the age and condition of your cells, this brings the cell to something like 99.5% full charge. The top off charge runs for 2 hours and adds the last 0.5% of the charge.

The top off current is not displayed, nor is the maintenance current. You can see how things are going by checking the voltage of the cell. The voltage at the end of the charge will be 1.47 volts. When the charge ends the voltage will drop slightly, then rise over the next 2 hours during the top off charge. Then it will drop back down.

The maintenance charge is designed for low self discharge cells in mind and is very low to prevent overcharging damage. Still, the best practice is to remove the cells from the charger when the charge is complete.

When you take a cell off of a charger its voltage will drop. That means that if you put a charged cell into the C9000 it will charge it until the charge termination is triggered. If the cell is already full, very little time will be needed to charge the cell, but some time will be needed. If you did this something like 1000 times, it is possible that you could produce overcharge damage to an Eneloop cell. The system is pretty good, but it is not perfect. It is still recommended to attend to the charge and stop it if you determine anything strange going on.

One of the fun things to do is to check the performance of your other chargers. Charge some cells in your other chargers, let them sit for about 30 minutes, then put them into the C9000 and do a discharge. Come to think of it you can check to see how beneficial the top off charge is. Charge your cells until you see Done, then pull them from the charger, wait 30 minutes, then do a discharge to determine capacity. Next do the same thing but this time allow the cells to stay in the charger for the 2 hour top off charge. Compare your results to determine how much the top off charge benefits the capacity of the cell.

Have fun.

By the way you can train your wife to use the charger. Tell her to put the cells in the charger and when it says Done to remove and use them. While there are many more features available, charging can be very simple.

Tom

[march.brown]

Hello March.brown,

By the way you can train your wife to use the charger. Tell her to put the cells in the charger and when it says Done to remove and use them. While there are many more features available, charging can be very simple.

Tom

Thanks for all the info Tom.

w.r.t. My Wife doing her own charging , I don't think I would lke that ... That would open the door for her to show me how the cooker , the washing machine and the dishwasher worked.

"Horses for courses" as the saying goes ... A man has to justify his hobbies by making chargers etc sound very complicated to use ... She did have a look at the display on the C9000 then shrugged and walked away ... I did try to explain how it worked and showed her the diagrams in the instructions , but she just went into the kitchen.
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[march.brown]

Topoff runs 2 hours. You get no information regarding progress or current (an irritating flaw in the UI).

I let the charger terminate and topoff by itself.

Hi Yamabushi

I have had a play for a few hours with the C9000 and the voltage does carry on increasing when the "DONE" is displayed ... The voltage creeps up slowly to 1.48V over a period of about two hours which is obviously the "Topoff" period ... Then during what I asume is "Maintenance charging" , the voltage slowly drops to 1.45V ... This is the point at which I removed the cells from the charger.

If I remove a cell which displays "DONE" then put it back in again , the cell is charged again at one amp (or thereabouts) for about one minute (matbe less) then "DONE" comes up again ... The display shows that a few more mAh has been put into the battery and a time of one minute is displayed ... I suppose if this was done a few times it would top up the cell a bit more quickly ... Certainly the charger stops the one amp charge in less than a minute ... I am very happy with the charger now ... Should have bought one earlier , though they were a lot more expensive until recently.
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[Wrend]

It is most likely better for the cells to top them off slowly in this manor, and helps to keep them cool. I also prefer to top off my cells to help insure that they're more balanced at a fully charged state.

[Yamabushi]

@ march.brown

Yes, the voltage will give you some indication of progress. I just wish that after "Charging", the display would show "Topoff" and the elapsed time for that step; then show "Done" when it's really finished and goes to maintenance charging rate.

I agree with Wrend. I think the reduced charge rate, lower temperatures and extended time are all factors in achieving maximum charge.

Rather than try to tell when each cell is topped off, I simply note the time that the last cell is "Done", wait at least 2 hours, then pull all the cells.

[march.brown]

@ march.brown

Yes, the voltage will give you some indication of progress. I just wish that after "Charging", the display would show "Topoff" and the elapsed time for that step; then show "Done" when it's really finished and goes to maintenance charging rate.

I agree with Wrend. I think the reduced charge rate, lower temperatures and extended time are all factors in achieving maximum charge.

Rather than try to tell when each cell is topped off, I simply note the time that the last cell is "Done", wait at least 2 hours, then pull all the cells.

I found that "DONE" always comes on at 1.46V then after about two hours the voltage gradually goes up to 1.47V or 1.48V though I did have a Hybrio show 1.49V ... After another hour or so , the voltage drops to about 1.45V or 1.46V ... I will now use the Hybrios in equipment that doesn't demand the ultimate in closely matched capacity and will only buy Eneloops from now on.

I also will be waiting for the last cell to say "DONE" and will wait for at least two more hours before taking them out of the charger ... Based on the voltage readings that I noted , I would be happy to leave the batteries on for rather more than the two hours ... After the two hours "Topoff" at 100mA , a 10mA float charge (maintenance) isn't going to damage the NiMh cells ... I wouldn't leave them on all day though , just for my own peace of mind.

In all fairness , you will only lose a small percentage of charge if you remove the batteries when the "DONE" comes on ... It's just that the cell capacity is maximised when the two hours of "Topoff" has elapsed.

Perhaps in the future , the next generation will show that the charging is "done" but the "topoff" is in progress ... Then "Topoff Done" will display ... That would be one step nearer perfection ... Till that happens , I will just add a couple of hours or more onto the "DONE" time.
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[apagogeas]

...
If I remove a cell which displays "DONE" then put it back in again , the cell is charged again at one amp (or thereabouts) for about one minute (matbe less) then "DONE" comes up again ... The display shows that a few more mAh has been put into the battery and a time of one minute is displayed ... I suppose if this was done a few times it would top up the cell a bit more quickly ... Certainly the charger stops the one amp charge in less than a minute ... I am very happy with the charger now ... Should have bought one earlier , though they were a lot more expensive until recently.

From what I can recall from memory, 1A charge will bring the cell up to around 95% full. The rest will be filled up by the 2 hours top up. NiMH can easily handle high currents during charging up to 80-90% or so (what the 15 minute chargers take advantage of). However, the remaining 10%, if pumped in with the same high current, it stresses the cell and reduces the useful life. So, indeed you may put much quicker the missing 5% capacity instead of waiting for the top up to finish, however this approach invalidates the very first reason served by the top up; to fill up the cell gently so not to stress and ruin it much quicker. I really wouldn't miss a 5% charge if I'm in a hurry and can't wait for a top up to finish, if this means my cells will live longer.
Also, doing so lurks a dangerous situation. Maha is smart enough so not to miss a fully charged cell, although it still needs to put current for 1 minute to figure that out. However, if you had another charger which rely just on -dV, a fully charged cell may not produce that necessary -dV (the cell is past the point of that signal), so it will pump in current till the timer expires. We can't be certain even for maha, it may be fooled in that case. Of course this is rather bad if it happens.

[march.brown]

Perhaps in the future , the next generation will show that the charging is "done" but the "topoff" is in progress ... Then "Topoff Done" will display ... That would be one step nearer perfection ... Till that happens , I will just add a couple of hours or more onto the "DONE" time.
.

Just realised that if the C9000 displayed the charging current after the "DONE" comes up , that would enable us to see the 100mA and the 10mA periods of charge ... The cells could be removed when the 10mA figure showed ... That must be a very easy mod for Powerex to do.

I am charging my AAA's at 400mA at the moment ... They are all 800mAh cells ... Does the "Topoff" still stay at 100mA when the charging rate is only 400mA ? ... After "DONE" comes up , the C9000 would try to put 200mAh (2 hours at 100mA) into a 95% charged 800mAh cell ... This 200mAh into a 2000mAh cell is an extra 10% , but into a charged 800mAh cell it is 25% ... Would it be better to only give the AAA cells a one hour "Topoff" ? ... I will remove the AAA cells after one hour just in case.

It would be nice if the C9000 had a memory so that at the press of a single button you could tell it to charge all four slots at 400mA ... It's no real hardship for me to alter the charge current manually for AAA's as I only have about twenty ... I will always charge my AA Eneloops at the 1000mA so that suits me fine.

The charger and batteries all seem to stay quite cool during use .. So far I am very impressed with the chargers performance..
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[apagogeas]

Maha charges up to 95% because it usually terminates on voltage. If the termination is on -dV, the cell will be at 100% SoC (this signal occurs after the cell is fully charged). The ideal maha for me would know which method terminated the charge and based on that to decide if a top up is needed. If it is on voltage, a top up can be applied, if it is on -dV, no top up. The charging efficiency beyond a SoC is not 100%, also the lower the charging current, the lower the charging efficiency (around 70% for 0.1C). Therefore, even the 2 hours top up at 100mAh will not put 200mA in the cell. From one point of view, a 2000mAh cell under top up is like being charged at 0.05C and a 800mAh at 0.125C which is about what the break-in do to saturate the cell. True, cells with lower than 1000mAh, this will be tougher anyway but it will not result in a 25% overcharge due to charging inefficiency at that stage. Problems are pronounced with capacities below 700mAh, where the top up is more close to 0.2C which isn't very healthy anyway. I'd love a maha that sets the top up at 0.1 * charging rate (or max 100mA), so in the case of AAA, it would be 40mA for a 400mA charge, much gentler than the current 100mA setting. Anyway, what is more damaging to a cell is to leave it on the charger forever on trickle charge. LSD do not lose even those 10mA/hour.

[march.brown]

Maha charges up to 95% because it usually terminates on voltage. If the termination is on -dV, the cell will be at 100% SoC (this signal occurs after the cell is fully charged). The ideal maha for me would know which method terminated the charge and based on that to decide if a top up is needed. If it is on voltage, a top up can be applied, if it is on -dV, no top up. The charging efficiency beyond a SoC is not 100%, also the lower the charging current, the lower the charging efficiency (around 70% for 0.1C). Therefore, even the 2 hours top up at 100mAh will not put 200mA in the cell. From one point of view, a 2000mAh cell under top up is like being charged at 0.05C and a 800mAh at 0.125C which is about what the break-in do to saturate the cell. True, cells with lower than 1000mAh, this will be tougher anyway but it will not result in a 25% overcharge due to charging inefficiency at that stage. Problems are pronounced with capacities below 700mAh, where the top up is more close to 0.2C which isn't very healthy anyway. I'd love a maha that sets the top up at 0.1 * charging rate (or max 100mA), so in the case of AAA, it would be 40mA for a 400mA charge, much gentler than the current 100mA setting. Anyway, what is more damaging to a cell is to leave it on the charger forever on trickle charge. LSD do not lose even those 10mA/hour.

I have just charged 12 AAA cells (in the C9000) that were charged two weeks ago in one of my other chargers ... With my other chargers , I normally remove the charged batteries when the charger indicates that the charge is complete ... Theoretically they should all have been in the same state of charge.

The Eneloops were all displaying "DONE" within two or three minutes and their charge given showed between 21mAh and 25mAh ... So the Eneloops were still virtually fully charged , which is what I expected (or hoped for) ... My Recyko cells were showing between 43mAh and 44mAh before they were "DONE" ... My Hybrios were showing a wider spread between 25mAh and 49mAh ... I won't be buying any more of these Hybrio or Recyko AAA's and will stick with Eneloops till perhaps something better comes along in the future.

After a one hour topoff I removed four of the AAA's and then replaced them and put them back on charge at 400mA ... They all came up as "DONE" after one minute and 1mAh was displayed for each of them ... I will now standardise the AAA charging rate at 400mA and will leave them charging for only one hour after the "DONE" is displayed.

I'm happy now I've had a little play !
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[PEU]

I'm not sure if I missed it or anything, but is there a way to determine the capacity of the battery without using R&A? Like plugging it in then pressing some buttons and it will show the status of the battery.

Check ZTS battery testers


Pablo

[fiberguy]

Two things that I'd really like on this charger would be:

A switch to activate a tone signaling the charging cycle is complete

A separate timer that begins counting UP for each channel once charging is complete (although noting the time you started your charge would work as well)

Another user on another thread mentioned data storage for individual battery charge info and the ability to interface on a computer, also excellent ideas. I'm just sayin, if they're gonna be the best, why not go all out?