Power Me Up
Enlightened
The version that you've got includes the improved charge termination algorithm - it's only the versions starting with 0F that had that problem.
Maha MH-C9000, the Wizard One Charger (Part 2)
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SilverFox
Flashaholic
Hello Burgess,
If your charger works properly, I don't see any reason to be concerned. The original release of the C-9000 worked very well with healthy cells. The "improvements" were added because a large number of people were trying to use and recover "crap" cells.
This is not entirely true, but you get my drift...
In order to check out your unit, you will need to find a source of crap cells, because it is harder to get healthy cells to malfunction.
[sarcastic mode on]
You may be able to borrow some cells from a friend or neighbor that leaves them on the charger 24/7 to make sure they are always ready to go. This is one of the best ways to turn a healthy cell into a crap cell. The other source is to find cells that have been thrown into the back of the junk drawer. These are cells that stopped working well a while ago and were tossed into the back of the drawer instead of the recycle bin, hoping for a miracle to bring them back to life.
[sarcastic mode off]
To test your unit, you need to charge at the lowest charge rate, and set a timer. The charge should terminate after around 120-140% of the cells capacity has been put back in. The timer is a back up for you to terminate the charge if necessary.
The other issue is that the charger heats up when charging 4 cells at 2 amps. It is best to run this test with cells that are broken in and have been in constant use (i.e. NOT crap cells). Charge a set of 4 cells at 2 amps and check the temperature of the cells at the end of the charge. The cells should stay below around 140 F. Temperature is monitored at the negative end of the cell, so make sure your cells have good contact with the temperature monitoring strip when doing this test. This is not a test to run on new cells, or cells that have been in storage, until they have been properly broken in. The charger heats up while charging at 2 amps and some of this heat is passed on to the cells. If the cells are in a questionable condition, they will also heat up during a charge at this rate, and the combination can overheat the cells, sometimes melting the shrink wrap and sometimes causing the cell to vent. In the improved units, thermal paste has been applied to the junction of the temperature probe and the metal band that contacts the battery for better heat transfer.
My cells run up to around 120 - 130 F during 2 amp charging.
If everything checks out and works well, you are good to go.
Tom
If your charger works properly, I don't see any reason to be concerned. The original release of the C-9000 worked very well with healthy cells. The "improvements" were added because a large number of people were trying to use and recover "crap" cells.
This is not entirely true, but you get my drift...
In order to check out your unit, you will need to find a source of crap cells, because it is harder to get healthy cells to malfunction.
[sarcastic mode on]
You may be able to borrow some cells from a friend or neighbor that leaves them on the charger 24/7 to make sure they are always ready to go. This is one of the best ways to turn a healthy cell into a crap cell. The other source is to find cells that have been thrown into the back of the junk drawer. These are cells that stopped working well a while ago and were tossed into the back of the drawer instead of the recycle bin, hoping for a miracle to bring them back to life.
[sarcastic mode off]
To test your unit, you need to charge at the lowest charge rate, and set a timer. The charge should terminate after around 120-140% of the cells capacity has been put back in. The timer is a back up for you to terminate the charge if necessary.
The other issue is that the charger heats up when charging 4 cells at 2 amps. It is best to run this test with cells that are broken in and have been in constant use (i.e. NOT crap cells). Charge a set of 4 cells at 2 amps and check the temperature of the cells at the end of the charge. The cells should stay below around 140 F. Temperature is monitored at the negative end of the cell, so make sure your cells have good contact with the temperature monitoring strip when doing this test. This is not a test to run on new cells, or cells that have been in storage, until they have been properly broken in. The charger heats up while charging at 2 amps and some of this heat is passed on to the cells. If the cells are in a questionable condition, they will also heat up during a charge at this rate, and the combination can overheat the cells, sometimes melting the shrink wrap and sometimes causing the cell to vent. In the improved units, thermal paste has been applied to the junction of the temperature probe and the metal band that contacts the battery for better heat transfer.
My cells run up to around 120 - 130 F during 2 amp charging.
If everything checks out and works well, you are good to go.
Tom
SilverFox
Flashaholic
Hello Power Me Up,
Just to further confuse things, I have a 0F "improved" unit...
Tom
Just to further confuse things, I have a 0F "improved" unit...
Tom
Hello Power Me Up,
Just to further confuse things, I have a 0F "improved" unit...
Tom
Tom, what do you think is the primary termination criteria on the improved unit. It looks like my 0G0E01 unit terminates on maxV set to 1.47V (or 1.48V actuallysince i could see it hitting 1.47V mark and staying there for a minute or two).
I posted a separate thread about this, but no one cared to comment.
NiOOH, Maybe there is something totally different about AA Nimhs, but in my experience charging sub-C Nimhs, peak detection is never controlled by a particular max voltage. It is always controlled by a combination of voltage drop (in the range of a few thousandths of a volt) over time and cell temperature increase. I have had some of my better AA cells get to 1.50V at the end of a 2A charge.
One improvement idea for the the C9000 would be to have it display the voltage to a thousandth of a volt, and display it continuously during charging...
One improvement idea for the the C9000 would be to have it display the voltage to a thousandth of a volt, and display it continuously during charging...
PJbatman, I am not arguing against that, quite the opposite actually. In my experience the peak voltage depends on charging current, ambient temperature and the state of health of the battery.
That is why I find it interesting that my unit allways (no matter what cells and charging current I select) terminates the quick charge about a minute after the cells show 1.47V
I have a reason to believe that it terminates on maxV as I explained here
https://www.candlepowerforums.com/threads/175531
SilverFox
Flashaholic
Hello NiOOH,
I believe the C-9000 utilizes -dV termination. The difference between the original and the improved units has to do with the method of detection and the -dV value. I also believe there is a peak voltage cut off, but I think it is set to 1.6 - 1.7 volts. The display during charging shows the resting voltage and not the voltage under load, so that may explain why you often see 1.47 volts at the end of the charge.
I have not checked this, but it would be interesting to charge some NiCd cells and see if you get the same voltage at the end of the charge. NiCd cells usually terminate at a higher voltage than NiMh cells.
Tom
I believe the C-9000 utilizes -dV termination. The difference between the original and the improved units has to do with the method of detection and the -dV value. I also believe there is a peak voltage cut off, but I think it is set to 1.6 - 1.7 volts. The display during charging shows the resting voltage and not the voltage under load, so that may explain why you often see 1.47 volts at the end of the charge.
I have not checked this, but it would be interesting to charge some NiCd cells and see if you get the same voltage at the end of the charge. NiCd cells usually terminate at a higher voltage than NiMh cells.
Tom
I received my Wizard today from Thomas Distributing, and like PJbatman got revision 0G0B01.
Say, for instance, my, uh, neighbor had some of those crap cells he wanted to to miraculously bring back to life.I guess it would be wise to monitor the temperatures as Tom posted above.
Any reason to consider exchanging for a more recent iteration?
Say, for instance, my, uh, neighbor had some of those crap cells he wanted to to miraculously bring back to life.
I guess it would be wise to monitor the temperatures as Tom posted above.Any reason to consider exchanging for a more recent iteration?
GaryF
Enlightened
I managed to resist this for so long, but in a moment of weakness today I placed an order with Thomas Distribution for the MH-C9000. 
Tom,
If you read what I reported in this thread
https://www.candlepowerforums.com/threads/175531
you will see that there is a reason to believe that the peak voltage and much the less -dV is not reached during fast charging. Currently, I do not have any NiCd cells to try it with, but the fact that fast charge is terminated at 1.47V and the cells rearch 1.49V during top-off is strange.
It is true that the charger reports the offline voltage, i.e. with no load, but as far as I know the termination is also based on this measurement, i.e. the charger "looks" for -dV signal also offline. I agree that the voltage under the charge pulse will be higher (how much higher depends on the IR of the cell), but as long as the termination is based on offline voltage reading nothing is changed.
I also find it interesting that the charger cuts at 1.47V no matter what cells and chaging currents are selected. Older cells with higher IR typically run at higher voltages. Higher charging rates also bumps the voltage towards the end of charge. My BC900 and CCrane before that showed this higher voltages, but the c9000 is always terminating at 1.47V. Isn't that strange? You can check it for yourself. Take a 2Ah cell and charge it at 500 mA. Watch the display for the lasdt couple of minutes before done. Discharge and charge the same cell at 1.5-2 Amps and watch again. On my c9000 in both cases the charger terinates about a minute after the cell voltage has reached 1.47 V.
It is probably way overkill, but I have been keeping a small cooling fan on mine so far... I charged (4) @ 1.8A last night and they stayed cool. I also charged a few older 2300mah cells at 600 ma and they all perfectly stopped @~2550 mah input (they had all previously rated @ ~2250 on the C9000)
In my experience, the only time I overheated nimh cells was when I was charging a pack of 6 or 7 and they were not matched. The 0G0B01 seems to have a very good peak detection algorithm, and the higher the charge rate, the easier it should be...
But, I guess anything is possible with an older, unknown condition cell...
Bottom line is that you guys are going to love this charger!
wptski
Flashlight Enthusiast
Am I reading this correctly? Voltage doesn't peak and no dip either?? How could it ever work then?
SilverFox
Flashaholic
Hello NiOOH,
Interesting...
I charged some NiCd cells. At 1000 mA, the peak voltage displayed on the C-9000 was 1.47 volts, but I did see a 1.48 volt reading once. I then tried charging at 200 mA. The peak voltage displayed when charging at 200 mA was the same 1.47 volts.
Tom
Interesting...
I charged some NiCd cells. At 1000 mA, the peak voltage displayed on the C-9000 was 1.47 volts, but I did see a 1.48 volt reading once. I then tried charging at 200 mA. The peak voltage displayed when charging at 200 mA was the same 1.47 volts.
Tom
SilverFox
Flashaholic
Even more interesting...
I ran another batch of NiCd cells through and this time I had two of them signal Done at 1.54 volts. The other two signaled Done at 1.47 volts.
Tom
I ran another batch of NiCd cells through and this time I had two of them signal Done at 1.54 volts. The other two signaled Done at 1.47 volts.
Tom
I don't have any NiCd cells to try ot with, but with all my AA and AAA NiMH cells (these are in total 25 AA and 6 AAA in differenet capacity, age and condition) my 0G0E01 batch charger never exceeded 1.47V during the fast charge stage.
Wptski,
it could work by simply cutting-of at some predetermined voltage, which is IMO 1.47V.
In the past I've used two such chargers. One was a Kodak (don't remember the model #) which charged at 300 mA and cut-off around 1.4V It undercharged by about 20%. The other charger that I still own is an even slower overnight charger made by a Chinease company named Konnoc. It charges at 170 mA and cuts off below 1.4 V.
Actually, maxV is the only semi-reliable method to terminate at charging currents below 0.4-0.5C. Usually it is set too low for safety reasons resulting in undercharged cells.
Wptski,
it could work by simply cutting-of at some predetermined voltage, which is IMO 1.47V.
In the past I've used two such chargers. One was a Kodak (don't remember the model #) which charged at 300 mA and cut-off around 1.4V It undercharged by about 20%. The other charger that I still own is an even slower overnight charger made by a Chinease company named Konnoc. It charges at 170 mA and cuts off below 1.4 V.
Actually, maxV is the only semi-reliable method to terminate at charging currents below 0.4-0.5C. Usually it is set too low for safety reasons resulting in undercharged cells.
2 interesting MH-C9000 experiences lately...
1) I ordered a second MH-C9000 last week from ThomasDist and it was yet another 0G0B01 model, after I have seen several people report getting 0G0C01, 0G0D01, 0G0E01 .... It is running great though, just like my first one, so I am very happy!
2) On the issue of a particular maxV termination level, I was charging a few nimh AA, I think 2100mah, that were already ~50% charged. They peaked at 1.51V just prior to terminating. I think I was charging at ~1amp...
Have Fun!!
1) I ordered a second MH-C9000 last week from ThomasDist and it was yet another 0G0B01 model, after I have seen several people report getting 0G0C01, 0G0D01, 0G0E01 .... It is running great though, just like my first one, so I am very happy!
2) On the issue of a particular maxV termination level, I was charging a few nimh AA, I think 2100mah, that were already ~50% charged. They peaked at 1.51V just prior to terminating. I think I was charging at ~1amp...
Have Fun!!
We know this charger terminates based on voltage and negative delta V, but has anyone considered temperature into the equation? The reason I bring this up is because of the small metal strips about 1/4 up the charging channels. It's obvious they're not there for looks nor do they make contact with the electrical components of the battery, which leads me to believe they're used for measuring temperature. I know Maha is tight lipped about the charging algorithm, but that doesn't mean those of us here can't speculate.
Codeman
Flashlight Enthusiast
- Joined
- Nov 26, 2004
- Messages
- 2,690
No need to speculate. Those are temp sensors. I don't believe they play a part in the charging algorithms, though - they're simply a safety feature.
TorchBoy
Flashlight Enthusiast
My Eneloop AAAs terminate at 1.51V and hold there for some time after "done" is displayed, presumeably while the top off charge is still going. I normally remove them when the voltage starts to drop again. Just once recently I had one cell increase to 1.52V while being topped off.
