Maha MH-C9000 SUPPORT / FAQ - continuation

[bmoorhouse]

I have a two year old C9000 (code 0G0B01). It seems to work okay with AA batteries with only the occassional missed termination. With AAA batteries, however, it is 50-50. Last night I forgot to check it before going to bed and found it had forced 3150 into an 800 mah battery. Unfortunately, that isn't the fist time.

I bought this charger in particular because I liked the way the delta-V was suppose to work to ensure my batteries were fully charged (maybe slightly overcharged) every time. I knew I could charge the batteries for my flash and know I was getting max performance when the C9000 said Done.

After cooking another set of batteries last night, I returned to this board after being away for about a year and found that there is apparently a third firmware version that terminates charging at 1.47 volts instead of the delta-v.

I am considering replacing my current (firmware version 2) model with the new one to better protect my AAAs, but am concerned that doing so will negate the reason I bought the thing in the first place in that Done will no longer mean Done, but only Nearly Done.

In general, are people with the third version happier with it, or should I stick with my current one and just accept that my AAAs are going to get toasted every once in a while? Are there any other changes between the 2nd and 3rd versions I should know before I decide (besides the brighter screen)?

[Mr Happy]

I have an 0G0D01 model and it does have the 1.47 V feature. Until now, I had thought all 0G0 models had that.

Could you give more information like make and age of the battery in question, and charging rate used?

[fireguy]

Last night I forgot to check it before going to bed and found it had forced 3150 into an 800 mah battery. Unfortunately, that isn't the fist time.

I have a C9000, dated 0H0DA. Last night was the first time it ever missed termination on a AAA. I was charging an old Energizer 800 mAh AAA at 500 mAh. I noticed this when there was 2700 mAh put into the cell. The voltage displayed on the C9000 at this point was 1.35 volts. This is a very old cell. It had been charged the week before and the voltage (measured with a DMM) was 0.89V. I suspect this cell is gone and wonder if any charger would have terminated? I'm going to try it in another smart charger I have to see what happens. I wonder if the cell you were charging has problems? This is the only AAA that I have ever had any problems with in the C9000.

[bmoorhouse]

Most of my AAAs are Rayovak Hybrids, are about a year old, and have been used in my toddler's toys. I typically charge them at 400 ma as they are rated at 800 mah. If I use a decharge mode, I discharge them at 200 ma. When I pulled the battery this morning, I believe the voltage was at 1.51.

My concern is that it is not always the same battery that fails to terminate, nor is it the same slot. It is completely random.

I have two different batteries in the charger for an RA cycle. I started them within a minute of each other. The display is now showing:

Slot 2: Charging 1444 mah 390 ma 244 min 1.41 v
Slot 3: Resting 905 mah 92 min 1.43 v

It looks to me like the cell in slot 2 failed to terminate and has been charging the whole time that the cell in slot 3 has been resting. I did not note the time, so I do not know if the battery that missed last night failed to terminate on the initial charge or on the final charge.

[digitor]

The only puzzle is my charger is also from 2007 (0G0E01 from memory), but it produces results similar to chargers B and C.

I think the "G" indicates updated firmware - my C9000 is 0FAB02, and is the initial firmware version. I seem to remember there was a couple of revisions, with the "repeating digit" bug the last thing to get fixed.

Cheers

[Mr Happy]

Slot 2: Charging 1444 mah 390 ma 244 min 1.41 v
Slot 3: Resting 905 mah 92 min 1.43 v

It looks to me like the cell in slot 2 failed to terminate and has been charging the whole time that the cell in slot 3 has been resting. I did not note the time, so I do not know if the battery that missed last night failed to terminate on the initial charge or on the final charge.

It does indeed look like slot 2 has failed to terminate. Does the cell feel hot at this point? One would expect it to be getting quite warm with that charge current for so long.

[Mr Happy]

I think the "G" indicates updated firmware - my C9000 is 0FAB02, and is the initial firmware version. I seem to remember there was a couple of revisions, with the "repeating digit" bug the last thing to get fixed.

I think I read somewhere that the first two letters are the year and the second two are the month.

So 0F = 2006, 0G = 2007, 0H = 2008; 0A = Jan, 0B = Feb, etc.

My charger is actually 0G0D01, which would make it April 2007. I don't know exactly which month and year the second firmware revision was introduced. I do know that my charger has a digit display bug in Cycle mode that was apparently fixed in the third revision.

[bmoorhouse]

Yes, the cell did feel warm, though not as warm as the one I pulled out this morning with over 3000 mah.

I went ahead and pulled the cell out. I figured no sense in waiting for the 4000 mah cut-off.

One thing that surprised me though is that it was only showing 1.41 volts. Do the volts start going down at some point? Otherwise the 1.47 v cutoff on the new model wouldn't have helped here. And again, I could be wrong, but I am fairly positive the one I pulled this morning was at 1.51 v.

[Mr Happy]

Yes, the cell did feel warm, though not as warm as the one I pulled out this morning with over 3000 mah.

I went ahead and pulled the cell out. I figured no sense in waiting for the 4000 mah cut-off.

One thing that surprised me though is that it was only showing 1.41 volts. Do the volts start going down at some point? Otherwise the 1.47 v cutoff on the new model wouldn't have helped here. And again, I could be wrong, but I am fairly positive the one I pulled this morning was at 1.51 v.

Yes, pulling the cell was wise.

Those voltages do seem low to me. This is pure speculation, but one way a cell could have a low voltage, high charging current, and yet not be sizzling from overcharging is some kind of internal short circuit fault in the cell. It is all a mystery to me though, I don't quite know what is going on there. I don't own any Hybrids -- I always use eneloops -- and eneloops go up above 1.50 volts every time on a break-in cycle which means the 1.47 V cut-off always catches them on a normal charge.

I remember some questions in a thread somewhere about how to insert AAA cells in the charger. Can I check that you are pushing the cells right down firmly into the bottom of the slot so they make good contact with the temperature sensor? That's because even if charging doesn't terminate on voltage, it should eventually terminate on temperature.

[Bones]

...
I am considering replacing my current (firmware version 2) model with the new one to better protect my AAAs, but am concerned that doing so will negate the reason I bought the thing in the first place in that Done will no longer mean Done, but only Nearly Done.

In general, are people with the third version happier with it, or should I stick with my current one and just accept that my AAAs are going to get toasted every once in a while? Are there any other changes between the 2nd and 3rd versions I should know before I decide (besides the brighter screen)?

....

I went ahead and pulled the cell out. I figured no sense in waiting for the 4000 mah cut-off.

One thing that surprised me though is that it was only showing 1.41 volts. Do the volts start going down at some point? Otherwise the 1.47 v cutoff on the new model wouldn't have helped here. And again, I could be wrong, but I am fairly positive the one I pulled this morning was at 1.51 v.

It's my understanding that if your charger is reaching 1.51 volts it must be the first release of the MH-C9000.

The second release revised the charging protocols, and I'm not aware of any credible indication they have since been altered.

I specifically mention this because if my understanding is correct, then the capacity cutoff of your charger is 20000mAh and not 4000mAh.

I know of at least two further improvements since the firmware revision to the charging protocols. The first resolved the repeating digits bug in the cycle settings, the second increased the brightness of the display.

As well, at some point a nub was added to the negative tang for the AAA cell similiar to one on the negative tang for the AA cell.

It's also my understanding that the revision to the charging protocols was made on the fly in early 2007, and if your charger was built during this period, the only way to be certain it has the revised firmware is by determining its behaviour.

Probably the easiest way would be to point a camcorder at it while it's charging better quality cells that take it past the 1.47 volt termination point of the revised version, and then see what it does.

[Black Rose]

I think I read somewhere that the first two letters are the year and the second two are the month.

So 0F = 2006, 0G = 2007, 0H = 2008; 0A = Jan, 0B = Feb, etc.

My charger is actually 0G0D01, which would make it April 2007. I don't know exactly which month and year the second firmware revision was introduced. I do know that my charger has a digit display bug in Cycle mode that was apparently fixed in the third revision.

I have a 0G0KA that was purchased in March 2008.
It has the cycle mode digit display bug fix.

[Bones]

...

I am considering replacing my current (firmware version 2) model with the new one to better protect my AAAs, but am concerned that doing so will negate the reason I bought the thing in the first place in that Done will no longer mean Done, but only Nearly Done.

...

Perhaps you will find nearly done a more reasonable comprimise when placed in the context of this statement by William Cheu, the lead engineer on the MH-C9000:

...

4) Why isn't the battery fully charged when DONE shows? Why the 2hour topoff charge?

It is a balancing act between undercharging and overcharging batteries. Maha design chargers differently depending on the target market. In the case of the MH-C9000, we favor undercharging in order to extend battery life. Typically, batteries are 93-95% charged when DONE pops up. This is when the user-set charging current stops and the 100mA top-off current kicks in. Our research showed that this termination strategy will substantially increase the life of the battery by preventing overheating. I think most folks here will agree that the MH-C9000 is a "cool" charger.

...

As well, SilverFox has determined that the revised MH-C9000 actually provides a more complete charge than the BC-900, which terminates on Negative DeltaV the same as your original edition MH-C9000:

http://www.candlepowerforums.com ... post2650477

I'm presuming that the two hours top-off charge was included with the MH-C9000, but it's not stated.

[Turbo DV8]

Is it my imagination, or is the contact area of the thermal sensor with AAA cells kinda skimpy? Only a very small sliver of the very bottom of AAA cells actually contacts the sensor, and only half the width of the sensor is in contact with AAA cells. Seems kinda iffy to me. I wonder how effective the safety thermal termination functions on AAA cells with this charger...

Also, the negative contacts for the AAA cell just barely nips the end of the cell, which has caused me some charging problems no matter how hard I try to make sure the cell is pushed all the way down.


The two figures I need most from the display are mAh and voltage. I hate having to wait for each cell to cycle mAh-current-time to eventually show the voltage in the last display.

My wish list for the reordering of the display sequence:

mAh
Voltage
Current
Time

I actually find more need of time than current, but I place current before time to separate mAh from mA in the cycle, to better avoid inadvertently mistaking mA for mAh.

[EngrPaul]

UPDATE: Thomas Distributing had me ship the bad one back, they sent me a new one right away. THANKS!!!

[N162E]

Most of my AAAs are Rayovak Hybrids, are about a year old, and have been used in my toddler's toys. I typically charge them at 400 ma as they are rated at 800 mah. If I use a decharge mode, I discharge them at 200 ma. When I pulled the battery this morning, I believe the voltage was at 1.51.

My concern is that it is not always the same battery that fails to terminate, nor is it the same slot. It is completely random.

Have you considered a LaCrosse BC-700 or 900? This could be a good fit for you. The LaCrosse chargers sense DV at low ma much better. I have both. As I prefer slower charging I charge on the Lacrosse and do my discharges on the Maha.

My C-9000s are very early version and simply will not terminate below a 700 ma rate. On my Lacross's I can charge AAA at 200ma and AA at 500ma and have reliable termination and full cells at the end of charging.

As always quality and condition are important in charging and useage. Once a cell has had a "Good Cooking" it will probably never be the same and may be erratic/useless from that time on-time for the recycle bin.

[Timdog68]

Hi,
I have a new C9000,date code 0G0KA from Thomas.
I also bought a couple 4 packs of Eneloops from them as well.
I charged them and they are all were around 1850-1900 mah.
I am doing a break-in on 4 of them and noticing the voltage is up to 1.50V on all of them and its still charging.
Is it normal to get above the 1.47 volt cutoff when in Break-in mode?
Thanks,
Tim

[SilverFox]

Hello Tim,

Yes.

Tom

[NiOOH]

Yes, in break-in mode the cells are charged at 0.1C for 16 hours timed, i.e. the termination doesn't work. Fot the last few hours it is normal for the cells to reach voltages around 1.50 V. In any other mode the primary charge termination is done on maximum voltage set at 1.47 V. If a voltage drop is detected below this voltage (happens with lower quality cells) the charge is also terminated. It is also normal to see voltages higher than 1.47 during top-off (2 hours after "done" appears on the display) especially with AAA cells.

[jblackwood]

Hello Tim,

Yes.

Tom

I love this response! Nuff said.

[NeoteriX]

Hi, I just picked up one of these (semi) locally at a Battery Plus store. I was a little disappointed that the included manual was so meager, but now when I checked the CPF forums, I'm a little blown away by all the information present

A few Qs:

- My production code is 0H0FA -- the ones I usually see people mention have 0F0 or 0G0 in the nomenclature. What should I know about or can expect from the 0H0 series? Is this the newest incarnation? Are there problems with it?

- I've got a handful of batteries in a bag collecting dust (some of them date over 8 years old ) that I was hoping to revitalize with this charger for non-demanding use (for TV remotes and the like). Which process is the best way to do this? R/A or Break in?

- On that same note, how do I know when to give up on the battery and chuck 'em out (recycle)? Is there a certain % of its original life that they are effectively no good?

- Is it safe to go to sleep while the batteries are charging? I had read a few posts (that I don't quite understand fully) where the batteries did not stop charging past their design limit b/c something something terminating voltage. I was worried that I would have hard metal batteries melting and exploding while I slept, but at the same time, these cycles can get quite long!

- When the information online says to charge at .5C and discharge at .25C, is this of the "rated" capacity on the side of the battery, or the "effective" capacity as determined by Refresh/Analyze? The first set of cells I have were rated at 2400 mAH but R/A concludes they have a discharge capacity of ~1400-1500 mAH.

- How closely do people adhere to the .5C/.25C rules? It's nice that my batteries stay pretty cool and comfortable during the process, but I can get a little impatient (see fear about burning in sleep, supra); I am coming from a Duracell 15-minute charger. Yes, it's complete garbage, and I probably fried some of my batteries over the past year, but 15 minutes is pretty enviable.

Thanks in advance!

[Mr Happy]

Hi, I just picked up one of these (semi) locally at a Battery Plus store.

Congratulations on your purchase. You have obtained a wonderfully entertaining toy, er, I mean a powerful and sophisticated piece of test equipment...

The first two letters of the production code seem to be the year of manufacture, and I think 0H is 2008. You cannot directly tell much more than that.

The main thing to do is get familiar with how your cells and the charger behave.

If you have really old and unknown batteries, the best thing to start with is a Break-In cycle. This is long and slow, but safe and cool, and will give you a baseline idea of the battery capacity. When entering the capacity for the Break-In, use the capacity given on the label.

If you have new and regularly used batteries, you can treat them differently. If they are AA cells, discharge them to empty at 500 mA and then put them on a charge at a rate from 0.5C to 0.8C (use the label capacity for C). Watch this process and monitor how warm they get (if they get uncomfortably hot you might stop the charge prematurely). What you are looking for is to see how the charge terminates. Does the voltage reach 1.47 V and then say DONE soon after, or does the voltage fail to reach 1.47 V and let the cells continue charging for a bit longer before saying DONE? Newer and better batteries will tend to hit 1.47 V whereas older batteries will not reach it. Before you leave the charger unattended you want confidence in how effectively the charge process will terminate. The ideal is for the supplied charge to be no more than 110-120% of the label capacity.

After DONE appears, leave them on the charger for another two hours and then discharge them at 500 mA. See how this capacity compares to the label. Also watch the voltage during the discharge. For good batteries the voltage will start out above 1.30 V and will hit 1.20 V about half way through the discharge. For bad batteries the voltage will be noticeably lower. Check the capacity reported at the end. Good batteries will be within 90% of the label, bad batteries significantly lower.

If you have bad batteries, my experience is just go straight to a Break-In cycle. This is the "big gun". I have not found it worth messing around with Refresh/Analyze cycles for improving battery health.

[NeoteriX]

Does the voltage reach 1.47 V and then say DONE soon after, or does the voltage fail to reach 1.47 V and let the cells continue charging for a bit longer before saying DONE? Newer and better batteries will tend to hit 1.47 V whereas older batteries will not reach it. Before you leave the charger unattended you want confidence in how effectively the charge process will terminate. The ideal is for the supplied charge to be no more than 110-120% of the label capacity.

Thanks for the information! It's really helpful!

So for all niMH batteries, the 1.47V figure is key? How long do I have to watch to determine that it is not hitting 1.47 and still going on?

[NiOOH]

Thanks for the information! It's really helpful!

So for all niMH batteries, the 1.47V figure is key? How long do I have to watch to determine that it is not hitting 1.47 and still going on?

As a rough guide, charging at 0.5-1 C, the 1.47 V point is reached when the input capacity is roughly equal to 90% of the capacity of the cells. Thus, for Eneloops you should be watching them when the input capacity reaches 1800 mA, or 2 hours after the begining of the charge at 1 Amp. If some of the cells cannot reach 1.47 V they will get considerably warmer than the others. You may be even able to see the voltage dropping by 0.01 V a short while before the charger terminates.
This however is unlkely to happen with good quality cells. I've used the c9000 with 16 eneloops 8 Hybryos, 4 2500 mAh Sanyos and 8 1700 mAh Sanyos and all of them terminate without problems at 1.47 V. The only cells that may have problems are two (out ot four) Varta Ready 2 Use cells that reach 1.46 V

[Turbo DV8]

The C-9000 just missed a termination on a AAA ROV Hybrid @ 300 mA charge rate. I got home and it had put 2200 mAh through it. It wasn't particularly hot, but should I just toss it anyway?

[SilverFox]

Hello Turbo DV8,

Do a discharge at 400 mA, then do a charge at 600 mA and see what happens.

If your discharge capacity is less than 80% of the original capacity, you can stop with that and recycle the cell. On the other hand, if it has decent capacity, it may just need some exercise to get back into shape.

Tom

[Turbo DV8]

Hello Turbo DV8,

Do a discharge at 400 mA, then do a charge at 600 mA and see what happens. If your discharge capacity is less than 80% of the original capacity, you can stop with that and recycle the cell.

I did a discharge on it @ 400 mA this morning, and got back 668 mAh, which is on par with the lowest performing Hybrids I have, one of which is known to have high self-discharge. But at this point, I have no confidence in the 668 mAh figure, as well as waning confidence in the charger in general, due to the following.

When the Hybrid missed it's termination last night, I took it off the charger for an hour. My plan was to drain it and do a R&A. Before I went to bed, I set it to discharge at 100 mA, so it would be ready for R&A this morning. When I got up, the charger said DONE, but it indicated it had been in charge mode, not discharge, and it displayed "839 mAh." I know I did not accidentally set it to charge mode instead of discharge, as there is no 100 mA charge rate! This is the second time I have come back to the charger to find it finished in a mode other than what I set it for. Has this happened to anyone else?

So at this point, the 668 mAh figure and 839 mAh figure are worhtless to me. Did it charge, discharge, who knows? I am finding this charger to be just too finicky in several respects. I know some people don't trust the La Crosse, but I tell you, so far this Maha has given me more grief and strange occurences than my three La Crosse's ever have (since adding the filter caps, of course!) So I shall charge at 600 mA and do another 400 mA drain, and see what happens... if the C-9000 will let me. As far as the discharge capacity being less than 80% of the original capacity, unfortunately, I have no prior capacity data from this cell drained on the Maha, only the BC-900, so I won't be able to really compare before and after capacities.

[Power Me Up]

Before I went to bed, I set it to discharge at 100 mA, so it would be ready for R&A this morning. When I got up, the charger said DONE, but it indicated it had been in charge mode, not discharge, and it displayed "839 mAh." I know I did not accidentally set it to charge mode instead of discharge, as there is no 100 mA charge rate! This is the second time I have come back to the charger to find it finished in a mode other than what I set it for. Has this happened to anyone else?

It sounds like you might have had a very short power outage - long enough for the C9000 to reset. When the C9000 resets, it defaults to charging at 1000 mA after a few seconds, so I'd say that it had finished the discharge before the reset and then fully charged the cell - hence the 839 mAh being displayed...

[Turbo DV8]

It sounds like you might have had a very short power outage - long enough for the C9000 to reset. When the C9000 resets, it defaults to charging at 1000 mA after a few seconds, so I'd say that it had finished the discharge before the reset and then fully charged the cell - hence the 839 mAh being displayed...

Good to know. If it happens again, I should note charge current and time also. However, I was concurrently running break-ins on the second C-9000 at the same time, and there was no disruption on that unit. They were still in break-in mode.

[TakeTheActive]

...So for all niMH batteries, the 1.47V figure is key? How long do I have to watch to determine that it is not hitting 1.47 and still going on?

For *ALL* recent versions of the Maha MH-C9000 (SEARCH the CPF Archives for the *exact* version of the update), for *ALL* supported cell chemistries (NiCD and NiMH), MaxV has been reduced to 1.47VDC.

This does not apply to any other manufacturer's chargers.

[Bones]

Good to know. If it happens again, I should note charge current and time also. However, I was concurrently running break-ins on the second C-9000 at the same time, and there was no disruption on that unit. They were still in break-in mode.

It's curious that only one would have re-set. Perhaps a more sensitive power supply?

As well, have you been encountering problems with both your units, or have the problems you've been periodically reporting all been with the same unit?