Maha MH-C9000 SUPPORT / FAQ - continuation

[jhellwig]

I suppose I have a question about my c9000.


It seam like when I run the cycle mode my cells keep losing capacity until about the 4th cycle and then they even out. Does anyone else's do this? It isn't much maybe 10-30 mAh every time.

 

[CliveBurt]

I was wondering if someone knows if the discharge algorithm changed at some point in time on the C9000's?

I have two C9000's, one bought in early 2007 with a date code of 0G0B01 (we'll call that one "Charger A"), and the other bought in 2008 with a date code of 0G0KA (we'll call that one "Charger B"). If I take a battery and run any kind of test that tells me the capacity of the cell, be that a break in or refresh and analyse or discharge, charger B is anywhere from 93mAh to 130mAh lower than charger A. For instance, I just bought 8 new Eneloops and ran a refresh and analyse (C = 1000mAh, D = 500mAh) on each cell in both chargers and got the following results:

Cell/Charger A/Charger B/Difference
1/2008/1891/117
2/2017/1899/118
3/1952/1859/93
4/2005/1900/105
5/2030/1900/130
6/2045/1918/127
7/1978/1882/96
8/2020/1890/130

As far as I know both chargers use 0.9v as the termination voltage, so that only leaves the current measurement or the time measurement that isn't as accurate on charger B. I say charger B because charger A reads much closer to an Eneloops rated capacity and from my experience with Eneloops they are very consistent. I keep pretty good records of my batteries but never connected the dots, till now, that charger B reports lower capacities all the time. Is this a well known firmware change or is my charger B out of calibration?

Thank you in advance for any thoughts and help you can provide.

Clive

 

[Mr Happy]

I don't know, but to my mind charger B seems more likely to be true than charger A. I'm surprised though, that there could be such a difference between them.

What happens if you compare readings on the break-in cycle?

 

[CliveBurt]

Mr Happy,

Thank you for taking the time to reply. Is there any particular reason that you think charger B is correct?

As far as comparing Break-In cycles, that would be no, not yet. I have one under way right now that should provide the second part of a comparison but that won't finish the discharge till this time tomorrow. Is there a particular reason why you have asked about break-in cycles? If it is in order to know that the batteries were completely charged before the discharge was started then maybe the following will set your mind to rest.

I charged cells 1-4 on charger A for 6 hours at a charge rate of 1000mAh.
So that should have given them plenty of time for "Top off" charging and also start trickle charging. To my knowledge of the C9000 that should make these cells well charged. Then I discharged them at 500mAh. I then recharged them on charger A for 6 hours and discharged them on charger B at 500mAh. Here are the results:

Cell/Charger A/Charger B/Difference

1/1992/1885/107
2/2000/1887/113
3/1935/1846/89
4/2004/1886/118

I charged cells 5-8 on charger B for 6 hours at a charge rate of 1000mAh.
So that should have given them plenty of time for "Top off" charging and also start trickle charging. To my knowledge of the C9000 that should make these cells well charged. Then I discharged them at 500mAh. I then recharged them on charger B for 6 hours and discharged them on charger A at 500mAh. Here are the results:

Cell/Charger B/Charger A/Difference

5/1880/2007/127
6/1893/2021/128
7/1851/1954/103
8/1874/2001/127

These are the same cells as used in the Refresh and Analyse (RA) testing from my earlier post.

I have borrowed my brothers C9000 that was bought at the same time as my Charger B and has the same date code. I'm just charging up cells 1-4 so that I can run a discharge using my brothers charger. Should have those results later on today and also have break-ins running on chargers A & B that should be finished tomorrow. However, the cells being broken-in (BI) aren't the same cells that I've used so far, but I do have their history recorded.

Has anyone compared capacity results from Hobby chargers to C9000 for new Eneloops? I was wondering what sort of capacity to expect from a 2000mAh Eneloop.

 

[Mr Happy]

The reason I thought charger B was correct was a comparison with my own charger. I usually find that Eneloops measure in the 1850-1900 range when discharged after a normal charge on my C9000, compared to a measurement in the 1900-2000 range after a break-in. Therefore your charger B numbers seemed closer to what I am familiar with than charger A. Capacities much above 2000 mAh are quite unusual for Eneloops, and so measurements up to 2045 mAh seemed remarkable to me.

Note that I originally didn't have your additional information about waiting 6 hours for the top off to complete. In that case the sub-1900 capacities from charger B do seem suspect.

The reason I asked about break-in was this post from William Chueh higher in the thread:

I trust the BREAK-IN capacity on the MH-C9000. It typically is within 2% of the capacity measured on a calibrated battery analyzer.

If break-in capacities are expected to be within 2% of the truth, then a variation of more than 5% between chargers for the same cells would be significant and would seem to indicate that one or other charger is out of calibration.

 

[CliveBurt]

My first post was the results from refresh and analyse cycles which I thought included a 2 hour rest cycle during which I assumed that the top up charge was being applied (Might be wrong on that) before the discharge cycle starts, so I figured that it would be a quicker comparison than doing a BI.

I'll just show you the history of a set of cells that I have on BI right now so that you can add that into your thinking. These are Nexcell 1600mAh that came with a charger I bought 3 years ago. This isn't the full history just RA's and BI's:

Date/Operation/Charger/Cell #1/Cell #2/Cell #3/Cell#4
05-07-08/RA/A/1247/1146/1452/1197
06-07-08/BI/A/1240/1145/1481/1166
27-07-08/RA/A/1221/1124/1540/1161
30-12-08/BI/B/1122/1033/1456/1067
05-02-09/BI/A........

As you can see they're not really what one might call a matched set! They just happen to be one of the two sets that have had BI's run on charger B. In between the RA on 27/07/08 and the BI on 30/12/08 these batteries sat for 125 days and then were discharged and then charged. They then sat for 21 days and then discharged and charged. Then sat for 7 days and discharged and charged. I then installed them in a set of electronic bathroom scales until this morning when I discharged them in order to start a BI on charger A just to verify that they haven't really lost 100mAh of capacity since their last BI on charger A.

In about 3.5 hours I should have the discharge results from my eneloops on my brothers charger. If they're the same as charger B then I'm still not really any the wiser. I don't know if it's a firmware change or if charger A is out of calibration. It would be really nice if they match charger A, in which case my brother can take charger B back to the USA when he goes in a couple of weeks time. Anyone know how long it takes Thomas Dist. to sort out replacements for this kind of thing?

 

[Turbo DV8]

Note that I originally didn't have your additional information about waiting 6 hours for the top off to complete. In that case the sub-1900 capacities from charger B do seem suspect.

My first post was the results from refresh and analyse cycles which I thought included a 2 hour rest cycle during which I assumed that the top up charge was being applied (Might be wrong on that) before the discharge cycle starts...

Of 30 AA Eneloop's I have, only 10% of them come in above 1900 mAh on a R&A at 500mA charge and discharge. Earlier, Maha posted here that the "2-Hour top-off charge is applied in all modes except in DISCHARGE and BREAK-IN."

 

[digitor]

FWIW, our local agent for the C9000 reckons that there is about a 6% difference in the capacities reported by the "old" and "new" versions of the charger. This seems to tally with the results obtained by CliveBurt.

Cheers

 

[CliveBurt]

Here are the results of cells 1-4 after being discharged on my brothers C9000 (Charger C) with the same date code as my Charger B:

Cell/Charger A/Charger B/Charger C

1/1992/1885/1885
2/2000/1887/1882
3/1935/1846/1839
4/2004/1886/1889

Thank you for your input Digitor, it confirms what I'm seeing.
I'm glad that my Battery history records have which particular charger the operation was carried out on. I have just recently retired a load of batteries not because of lost capacity but because of VERY rapid self discharge. A set of four Duracell 2650's 100% self discharge in 7 days!
I've gone through my histories and checked that this difference between chargers hasn't led me to the wrong conclusions. The only time it's led me astray was with some self discharge testing that I did to compare my Eneloops against some UniRoss Hybrios and Vapex instants. The UniRoss and Vapex were BI'd on charger A and then a long time later the discharge test was done on Charger B where as the Eneloops were discharged on Charger A so the Eneloops came off looking much better. It's just a pain in the rear having to now possibly wait to get a set of batteries on the "right" charger. That's why I bought a second C9000! So I didn't have to wait for a BI to finish.

I wonder if Thomas Dist. will exchange my old charger? Sod's Law says I'll end up with a new charger that will be different in it's firmware and I'll end up back where I started. Still, the AAA contacts couldn't be any worse than the ones on my Charger A.

 

[Mr Happy]

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

 

[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.