Maha MH-C9000 SUPPORT / FAQ Thread

[EngrPaul]

Hi Mike,

I have been wondering the same thing. I only goes directly to "Done" for me.

Paul

[wptski]

Has anybody seen the C-9000 do a "top off charge" as mentioned in the FAQ? I'd expect to see that following a charge termination on delta temperature but not if it terminated on -dV/dt.

I haven't seen it do that yet and I've been doing a lot of charge cycles and trying to monitor it fairly closely.

I was expecting dT/dt to be the normal charge termination since it was listed as a feature and should normally happen before -dV/dt.

Mike

Mike:

I just put a scope on one of my C9000 today. I just check on the graph and it just showed DONE and had to terminate by -DeltaV because it's connected outside the charger. It's barely warmed the 1.8Ah cells at 1A rate anyway. It's showing 160ma topoff rate.

PWM ON portion of the signal is rather noisey too. I have a pair of current probes that don't read exactly the same but close and I'm assuming that the noise/hash is causing one to read over 200ma lower than the other one!

[dekelsey61]

Paul+Mike, I don't believe you will see the charger go into top off charge. Mine has never said that in the week I have had it. It is the same thing as the trickle charge. You never see the charger go into that mode. We have to believe that when the DONE comes on for 1hour after that it is in the top off mode then the trickle charge begins.
Dan

[EngrPaul]

Paul+Mike, I don't believe you will see the charger go into top off charge. Mine has never said that in the week I have had it. It is the same thing as the trickle charge. You never see the charger go into that mode. We have to believe that when the DONE comes on for 1hour after that it is in the top off mode then the trickle charge begins.
Dan

This would be really nice to know.

But to have it display "DONE" when it really isn't? Kinda defies logic, wouldn't you say?

[wptski]

This would be really nice to know.

But to have it display "DONE" when it really isn't? Kinda defies logic, wouldn't you say?

Just like the Duracell/Energizer 15 minutes chargers, even though the LED shows finished, it really isn't!

[Mike abcd]

Mike:

I just put a scope on one of my C9000 today. I just check on the graph and it just showed DONE and had to terminate by -DeltaV because it's connected outside the charger. It's barely warmed the 1.8Ah cells at 1A rate anyway. It's showing 160ma topoff rate.

PWM ON portion of the signal is rather noisey too. I have a pair of current probes that don't read exactly the same but close and I'm assuming that the noise/hash is causing one to read over 200ma lower than the other one!

That's really surprising. I wouldn't expect a top off charge after a -dV/dt but only after dT/dt.

I'd also expect .1 C and if I understand you correctly, you charged at 1000 mA and am seeing 160 mA.

If you notice it terminate, I'd be curious how long after the fast charge ended.

Thanks,
Mike

[Mike abcd]

I've run a bunch of cycles with 4 cells inserted that were previously charged and allowed to rest for 30+ minutes. I haven't seen any missed terminations at rates from 500-2000 mA on cells that tested 2100-2400 mA.

I also have run a few charge cycles on the same cells at 1000-2000 mA rates when they were fully discharged with no issues.

I'm going to play with older abused cells and partially discharged ones next.

Hey, in hope of a quick answer...can anybody tell me how to open the plastic belt "hoop/ring" on the newer style Fenix holsters. I'm too stupid to figure it out and I've tried pulling/twisting etc. Can't even see a seam...

Mike

[wptski]

That's really surprising. I wouldn't expect a top off charge after a -dV/dt but only after dT/dt.

I'd also expect .1 C and if I understand you correctly, you charged at 1000 mA and am seeing 160 mA.

If you notice it terminate, I'd be curious how long after the fast charge ended.

Thanks,
Mike

Mike:

It's listed as 100ma topoff not .1C. I just checked again and the topoff is still going pushing 80 minutes now. Yes, I was charging at 1A which was DONE at 90 minutes. Yes, it shows 160ma topoff rate. I wanted to save the results, maybe to post the graph here later. This is cutting into my sleep time now!

EDIT: That was a big waste of time, I was looking at the error in my probe as it wouldn't go to zero. I'll have to check my probes on some non-PWM current but I think that it's the hash coming from the charger that messing things up. Darn, I hate when you lose sleep over this hobby!

[bcwang]

Thinking about this whole top-off charge thing, this probably throws a wrench in how the analyze and cycle mode calculations work. I'm assuming there is no top-off charge in those modes (otherwise it'd be a very long wait), so you won't be getting as complete a charge for the test value. So your regular charge with the top-off should net better results than what you see in the analyze mode. Guess someone could try it one day by doing a regular charge, waiting 2-3 hours, then reset the battery and do the discharge test. That should give a higher reading than doing the regular analyze mode.

[moldyoldy]

Hi Mike abcd,

yup, I made the same mistake with the Fenix holsters. The belt loop is in the _double_ layer of fabric immediately behind the holster. I was slightly embarrassed too!

Tim

[wptski]

Thinking about this whole top-off charge thing, this probably throws a wrench in how the analyze and cycle mode calculations work. I'm assuming there is no top-off charge in those modes (otherwise it'd be a very long wait), so you won't be getting as complete a charge for the test value. So your regular charge with the top-off should net better results than what you see in the analyze mode. Guess someone could try it one day by doing a regular charge, waiting 2-3 hours, then reset the battery and do the discharge test. That should give a higher reading than doing the regular analyze mode.

bcwang:

I assume that there is no topoff during cycling mode till the last charge and if it is what it says, it's only 100ma@60 min. R&A mode, it might during the rest period but we won't know till we're told or me/somebody else checks it.

Today I'm going look into my current probe snafu from last night too.

[bcwang]

I wonder if I'm the first to have this happen. I have fujicells that don't detect in slot 1 and 2. It seems to have a shorter top contact and can't make contact with the charger because of the recessed design. There must be some manufacturing variation such that slot 3 and 4 on my charger has the contact a bit shallower so these same batteries do make contact.

On another note, for those of you who complained that batteries are hard to remove, I tried something new which I had always done on my c204w. Since I had a battery which could not be removed even when sliding it down first (probably longer than most), I found that removing the battery bottom first works easily. In fact, after that, I found inserting and removing all my batteries from the bottom first works much more easily. Looking at the design of the contacts in both the c204w and the c9000, it may even be by design that they want you to slide it in and out from the bottom contact. I noticed if you do it from the top, you just end up scratching the plastic around the contact and require substantially more effort to get cells in and out, on both of these chargers.

[EngrPaul]

When I first saw the charger would have a "lift rod", I became excited because I thought this was a cammed mechanism that would help eject the cells from their position with the throw of a lever. When I found out it was a little prop bar for the charger to sit up at an inclined angle, I was a little sad.

[willchueh]

Hello everyone,

The charger does not display the topoff or maintainence charging current on the LCD (e.g. the screen shows 0mA even if performing them).

DONE is shown after the program terminates, but before any maintainence and/or topoff charge. So, the charger is still applying small currents after DONE.

William

[BVH]

William, thank you so much for actively participating on this forum and providing us with this level of technical information and support! I look at it as quite a unique service on your part.

[willchueh]

William, thank you so much for actively participating on this forum and providing us with this level of technical information and support! I look at it as quite a unique service on your part.

A pleasure as always. When you buy something from Maha, we'd like to think you are buying a product and service.

William

[David M]

William, thank you so much for actively participating on this forum and providing us with this level of technical information and support! I look at it as quite a unique service on your part.

Could not agree more!!

The MH-C9000 is a marvel of engineering. Thanks, William

Regards,

David M

[wptski]

I wonder if I'm the first to have this happen. I have fujicells that don't detect in slot 1 and 2. It seems to have a shorter top contact and can't make contact with the charger because of the recessed design. There must be some manufacturing variation such that slot 3 and 4 on my charger has the contact a bit shallower so these same batteries do make contact.

On another note, for those of you who complained that batteries are hard to remove, I tried something new which I had always done on my c204w. Since I had a battery which could not be removed even when sliding it down first (probably longer than most), I found that removing the battery bottom first works easily. In fact, after that, I found inserting and removing all my batteries from the bottom first works much more easily. Looking at the design of the contacts in both the c204w and the c9000, it may even be by design that they want you to slide it in and out from the bottom contact. I noticed if you do it from the top, you just end up scratching the plastic around the contact and require substantially more effort to get cells in and out, on both of these chargers.

bcwang:

The instructions show how to insert cells but not how to remove them but if you reverse it, it's just how you suggest.

Have you popped one out and lost hold of it yet? I hope the LCD screen can take a good hit because it's going to get banged sooner or later!

[BVH]

If you're worried about screen damage, get some cheap Ipaq or other screen protector material for it. I did that with my Ipod because they scratch just by looking at it.

[wptski]

Finally figured out my current clamp probe problem. I assume the hashy PWM is causing my probes to not read correctly the pulsed current but the waveform doesn't lie. Calculating current by using the pulse width and lenght of one cycle figures to about 80ma on topoff rate. I marked the time a cell showed DONE. By the time I got set up and recoding the signal, I lost 15 minutes. The signal dropped to trickle charge at 1:42:40, so add 15 minutes to that and you got 2 hrs for topoff, not one hour as the specs mention. The trickle pulse was too narrow to measure.

I can post the graph but it isn't much more than a line but I may post the hashy PWM though!

[bcwang]

Finally figured out my current clamp probe problem. I assume the hashy PWM is causing my probes to not read correctly the pulsed current but the waveform doesn't lie. Calculating current by using the pulse width and lenght of one cycle figures to about 80ma on topoff rate. I marked the time a cell showed DONE. By the time I got set up and recoding the signal, I lost 15 minutes. The signal dropped to trickle charge at 1:42:40, so add 15 minutes to that and you got 2 hrs for topoff, not one hour as the specs mention. The trickle pulse was too narrow to measure.

I can post the graph but it isn't much more than a line but I may post the hashy PWM though!

That's the same topoff time as the c204w. I wonder if the topoff rate is the same. I remember the measurements were hard to average because of the pulsed nature of the charge current.

Did you get a different topoff rate for AAA cells?

[wptski]

That's the same topoff time as the c204w. I wonder if the topoff rate is the same. I remember the measurements were hard to average because of the pulsed nature of the charge current.

Did you get a different topoff rate for AAA cells?

bcwang:

I didn't check AAA"s rate but the specs only lists one topoff rate, although you'd think that it would be a bit lower.

[wptski]

Here’s a few scope of the C9000 and C808M to compare to. The first is a complete pulse which shows some hash/noise or whatever riding on the ON portion of the pulse. The second is a a few pulses from a C808M. The last is the C9000 with a shorter timebase to show the beginning of the pulse.

That shows a fluctuation of about 1.4A in amplitude. I've seen slightly distorded PWM before in chargers but nothing like this before. I'm clueless if this causes any harm or should be there to begin with but I'd say the better the square wave the better you are! Comments please.

[Curious_character]

Hello everyone,

The charger does not display the topoff or maintainence charging current on the LCD (e.g. the screen shows 0mA even if performing them).

DONE is shown after the program terminates, but before any maintainence and/or topoff charge. So, the charger is still applying small currents after DONE.

William

For how long is the 100 mA topoff charge applied after the end of the normal charge?
Is the topoff charge applied during the "rest" period between charge and discharge when cycling?

c_c

[wptski]

For how long is the 100 mA topoff charge applied after the end of the normal charge?
Is the topoff charge applied during the "rest" period between charge and discharge when cycling?

c_c

The instructions state one hour for topoff but I tested it with a scope and it goes for two hours. I did check the R&A mode and there was "no" topoff, so I'm assuming that during "all" other rest periods there'd be no topoff.

[paulr]

This looks like a great charger and is definitely on my 2007 shopping list even though I have numerous chargers already including a BC900. One feature I'd like to see in some update would be self-discharge analysis. You put in some batteries and the charger charges them up, then cuts charge rate to zero (i.e. no trickle charge). It then monitors the cell voltage (one measurement per day under load is probably enough) over a period of weeks or months, computing the self-discharge rate and identifying problem cells. I keep having cells develop charge retention problems and it's really annoying to try to identify them with manual measurements, labelling the cells, etc. I could even see buying at least one additional MH-C9000 for this purpose since the multi-week analysis keeps the charger tied up for such a long period.

[wptski]

This looks like a great charger and is definitely on my 2007 shopping list even though I have numerous chargers already including a BC900. One feature I'd like to see in some update would be self-discharge analysis. You put in some batteries and the charger charges them up, then cuts charge rate to zero (i.e. no trickle charge). It then monitors the cell voltage (one measurement per day is probably enough) over a period of weeks or months, computing the self-discharge rate and identifying problem cells. I keep having cells develop charge retention problems and it's really annoying to try to identify them with manual measurements, labelling the cells, etc. I could even see buying at least one additional MH-C9000 for this purpose since the multi-week analysis keeps the charger tied up for such a long period.

Buy a charger and it would have to be expensive, tie it up for weeks to find that your $3.00 cell is losing it's charge? Not me!

[paulr]

Huh? I aready have several chargers sitting around doing nothing, just like most of us do. If it can be sitting there analyzing self-discharge instead of sitting doing nothing, that's a big win. It's not like I'm using my charger all the time. And I have dozens of cells that might have this problem. At $3 each, getting 20 of them replaced by the manufacturer pays for a whole $60 charger.

[wptski]

Huh? I aready have several chargers sitting around doing nothing, just like most of us do. If it can be sitting there analyzing self-discharge instead of sitting doing nothing, that's a big win. It's not like I'm using my charger all the time. And I have dozens of cells that might have this problem. At $3 each, getting 20 of them replaced by the manufacturer pays for a whole $60 charger.

A ZTS MBT-1 will tell you that. Works for me.

[willchueh]

For how long is the 100 mA topoff charge applied after the end of the normal charge?
Is the topoff charge applied during the "rest" period between charge and discharge when cycling?

c_c

1) Topoff charge is applied for 2 hours.
2) Topoff charge and trickle charge not applied during rest period.

William