TorchBoy
Flashlight Enthusiast
I have one from this year that stops at 1.46V or 1.47V with my Eneloops, before the top-up charge which takes them to 1.50V or sometimes 1.51V. Which version is yours, jusko?
Maha MH-C9000 SUPPORT / FAQ - continuation
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Mr Happy
Flashlight Enthusiast
I have 0G0B01 and it stops at 1.48 V, but you have to watch very carefully to catch that. Once it stops charging the voltage drops in a few seconds to 1.47 V or lower so if you blink you will miss it.
The voltage actually drops all the way down to about 1.45 V and then slowly creeps up over the next hour to maybe 1.49 V on the top off charge before eventually resting back down to 1.44 V after two or three more hours.
The voltage actually drops all the way down to about 1.45 V and then slowly creeps up over the next hour to maybe 1.49 V on the top off charge before eventually resting back down to 1.44 V after two or three more hours.
Handlobraesing
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So, I've found this charger is no good at discharging batteries in not so good health or testing the capacity of batteries suffering a high internal resistance.
The termination voltage on discharge is fixed at 0.90v. The discharge current is fixed at 0.9-1A and you can not change it. Changing the current setting only changes the discharge duty cycle.
The discharge voltage is taken during on cycle, so the voltage is actually the voltage under 1A load. A deteriorating cell that works fine at 250mA that can't maintain 0.9v at 1A will cause this device to stop discharging immediately only to find that the battery still holds an open circuit voltage of 1.3v
If you want to cycle the cell to improve their health, this charger won't do it, because the discharging process will immediately terminate if the voltage under 1A load falls below 0.9v
So, 500mA discharge is really more like 1A discharge for one second, no discharge for one second, 1A discharge for one second and so on.
This charger is loaded with a lot of cool OPTIONS, but the method of modulating the current is flawed in my opinion.
Both the charging and discharging current is the maximum current and changing the setting only changes the 2 second time weighed average.
The termination voltage on discharge is fixed at 0.90v. The discharge current is fixed at 0.9-1A and you can not change it. Changing the current setting only changes the discharge duty cycle.
The discharge voltage is taken during on cycle, so the voltage is actually the voltage under 1A load. A deteriorating cell that works fine at 250mA that can't maintain 0.9v at 1A will cause this device to stop discharging immediately only to find that the battery still holds an open circuit voltage of 1.3v
If you want to cycle the cell to improve their health, this charger won't do it, because the discharging process will immediately terminate if the voltage under 1A load falls below 0.9v
So, 500mA discharge is really more like 1A discharge for one second, no discharge for one second, 1A discharge for one second and so on.
This charger is loaded with a lot of cool OPTIONS, but the method of modulating the current is flawed in my opinion.
Both the charging and discharging current is the maximum current and changing the setting only changes the 2 second time weighed average.
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SilverFox
Flashaholic
Hello Handlobraesing,
You have made an important discovery... Crap cells don't perform well. :devil:
I have found that it is far less frustrating to recycle crap cells and replace them with new cells that are performing well. However, there can be some educational opportunities from playing with crap cells.
If you want to play, try this...
Charge your cells at 1000 mA. When Done is displayed, set a timer for 3 hours. When the timer goes off, start a 500 mA discharge.
Record the capacity you get and compare it to the labeled capacity of the cell.
Leave the cells in the C9000 and set a timer for 30 minutes. Then do another discharge at 200 mA.
When that discharge is completed, once again, set the timer for 30 minutes, then do another discharge, this time at 100 mA.
Next, do a Break-In cycle. Once again, record the capacity and compare it to the labeled capacity.
Set a timer for 1 hour, then discharge at 500 mA.
Record the capacity and compare it with what you got during the first 500 mA discharge. If you see an improvement in capacity, the cell is starting to recover and you can repeat this process again.
After 10 rounds of this, if your crap cells are going to recover, they should be at or above about 80% of their labeled capacity.
On the other hand, if your crap cells are still crap, recycle them and move on. If you have a secial "attachment" to them, find a crap application for them and don't be frustrated when they crap out on you.
Have you tried running any healthy cells through charge/discharge cycles on the C9000? How did they do?
Tom
You have made an important discovery... Crap cells don't perform well. :devil:
I have found that it is far less frustrating to recycle crap cells and replace them with new cells that are performing well. However, there can be some educational opportunities from playing with crap cells.
If you want to play, try this...
Charge your cells at 1000 mA. When Done is displayed, set a timer for 3 hours. When the timer goes off, start a 500 mA discharge.
Record the capacity you get and compare it to the labeled capacity of the cell.
Leave the cells in the C9000 and set a timer for 30 minutes. Then do another discharge at 200 mA.
When that discharge is completed, once again, set the timer for 30 minutes, then do another discharge, this time at 100 mA.
Next, do a Break-In cycle. Once again, record the capacity and compare it to the labeled capacity.
Set a timer for 1 hour, then discharge at 500 mA.
Record the capacity and compare it with what you got during the first 500 mA discharge. If you see an improvement in capacity, the cell is starting to recover and you can repeat this process again.
After 10 rounds of this, if your crap cells are going to recover, they should be at or above about 80% of their labeled capacity.
On the other hand, if your crap cells are still crap, recycle them and move on. If you have a secial "attachment" to them, find a crap application for them and don't be frustrated when they crap out on you.
Have you tried running any healthy cells through charge/discharge cycles on the C9000? How did they do?
Tom
Handlobraesing
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Simple. There is almost no difference in read-out voltage in 100mA or 1,000mA, because the voltage reading is taken under load and 100mA is just 1A at 10% duty cycle.
The voltage falls below 0.90v(which is 0.95v at the terminals measured externally), then it immediately displays DONE Avail. cap 0mAh
The voltage falls below 0.90v(which is 0.95v at the terminals measured externally), then it immediately displays DONE Avail. cap 0mAh
Black Rose
Flashlight Enthusiast
Wow, thats a lot of time to try and recover a set of cells. I guestimated that process would take approx 25 days for 2000 mAh cells.
It would be interesting to see how much electricity would be used by the C9000 during that process compared to the results (i.e. is it worth investing $X.00 of electricity to attempt to revive the cells).
As a test to see how much power is used by the C9000, I currently have it hooked up to an energy meter to see how much power it uses for a 1A discharge cycle followed by a break-in cycle. I noticed a sizable spike on my last electricty bill, so I'm curious to see how much the break-in cycles played into that.
SilverFox
Flashaholic
Hello Handlobraesing,
OK, so your crap cells show 0 mAh under a 100 mA discharge on the C9000. What do you get after running the Break-In cycle?
Tom
OK, so your crap cells show 0 mAh under a 100 mA discharge on the C9000. What do you get after running the Break-In cycle?
Tom
Handlobraesing
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It wouldn't complete the break-in cycle. It would force charging at 2A * n% duty cycle and once it's done, it rests, and switch over to discharge, drops <0.90v and says "done".
If the cell can't hold 0.90v at full one amp, MH-C9000 will terminate prematurely. The voltage measurement is taken under pulse load which causes the voltage to drop to what you'd get under 1A load.
Mr Happy
Flashlight Enthusiast
I think the important part of the break-in cycle is the charging part. If the 16 hour 0.1C charge did not improve the performance of the cell to the point where it can sustain any discharge at all, then the cell is toast methinks.
SilverFox
Flashaholic
Hello Handlobraesing,
OK, we are making progress here...
So far your crap cells have 0 mAh capacity after a normal charge and a 500 mA discharge, and 0 mAh capacity after a 0.1C charge and 0.2C discharge.
Yet you claim that under a 250 mA constant load they work fine.
It's time to put them in a direct drive light, turn it on and let it run for around 4 hours. Hopefully you have a single cell light. If you need to run a pair of cells, you will have to watch it to make sure you don't ruin your crap cells further by reverse charging.
At the end of this, you will need to jump start the cells to get them to have enough voltage to start the C9000. Once you get the voltage of the cell up to where the C9000 recognizes it, you can run another charge/discharge and see if you get past 0 mAh.
Tom
OK, we are making progress here...
So far your crap cells have 0 mAh capacity after a normal charge and a 500 mA discharge, and 0 mAh capacity after a 0.1C charge and 0.2C discharge.
Yet you claim that under a 250 mA constant load they work fine.
It's time to put them in a direct drive light, turn it on and let it run for around 4 hours. Hopefully you have a single cell light. If you need to run a pair of cells, you will have to watch it to make sure you don't ruin your crap cells further by reverse charging.
At the end of this, you will need to jump start the cells to get them to have enough voltage to start the C9000. Once you get the voltage of the cell up to where the C9000 recognizes it, you can run another charge/discharge and see if you get past 0 mAh.
Tom
Handlobraesing
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That's basically what I'm saying... because it only samples voltage under 1A load, it terminates prematurely, so it's not a useful discharge device to actually get say... discharge to 0.9v at 0.1A.
SilverFox
Flashaholic
Hello Handlobraesing,
Actually, because of the pulsed discharge, it give slightly optimistic results compared to constant current discharging...
If you would like to do a comparison, you will need to pick up a CBA from West Mountain Radio, and a couple of new Alkaline AA cells. You will have to take some time and adjust the calibration of the CBA so that it is accurate at low current levels, then discharge a cell on the CBA at 100 mA with a discharge limit set to 0.9 volts, and also discharge another cell on the C9000 at 100 mA. You will find that the C9000 will give a slightly higher capacity.
When you move on from crap cells to healthy cells, what are you finding?
Tom
Actually, because of the pulsed discharge, it give slightly optimistic results compared to constant current discharging...
If you would like to do a comparison, you will need to pick up a CBA from West Mountain Radio, and a couple of new Alkaline AA cells. You will have to take some time and adjust the calibration of the CBA so that it is accurate at low current levels, then discharge a cell on the CBA at 100 mA with a discharge limit set to 0.9 volts, and also discharge another cell on the C9000 at 100 mA. You will find that the C9000 will give a slightly higher capacity.
When you move on from crap cells to healthy cells, what are you finding?
Tom
pobox1475
Enlightened
I just got a C9000 last week and am in the middle of running a couple break in cycles on some new Eneloop AAA & AA and old Rayocac NiMH. When that is done which mode should I use get the most accurate display of their capacities? I also have some really old AA NiCad's with the name Millennium on them but no current capacity listed. I had intended to see what performance they would give or attempt to revive them. Should I just toss them in trash?
Mr Happy
Flashlight Enthusiast
It depends on what you want to measure.
I'd say you will get the most accurate display of their capacities if you measure it in the way that corresponds most closely to how the cells will normally be used.
You should discharge the cells and then charge them on whichever charger and using whichever mode you normally plan to use. After this, rest them for a few hours or a day, and then discharge them on the C9000 using the discharge current that again most closely resembles your intended use. Conservatively you would probably use the highest 1 amp setting.
This procedure will tell you what you can actually expect from the cells (rather than a theoretical maximum that you will never likely see). You can compare this with the capacity reported on the break-in charge and see what the difference is. I have also found it interesting to charge on different chargers and discharge on the C9000 to see which chargers do best at supplying a full charge.
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SilverFox
Flashaholic
Hello Pobox,
At the end of the Break-In cycle, the capacity you see should come close to matching the labeled capacity of the cell.
With you NiCd cells, charge them at 1000 mA and discharge them at 500 mA and see what you get. If you think there is hope for them, they will also benefit from a Break-In cycle.
I might add that it is better to recycle than to toss in the trash...
Tom
At the end of the Break-In cycle, the capacity you see should come close to matching the labeled capacity of the cell.
With you NiCd cells, charge them at 1000 mA and discharge them at 500 mA and see what you get. If you think there is hope for them, they will also benefit from a Break-In cycle.
I might add that it is better to recycle than to toss in the trash...
Tom
pobox1475
Enlightened
I am trying to keep it as simple as possible and hopefully match the cells in the process. From what you stated I can use the reading at the end of Break In to get an idea. I thought I might have to run a Refresh & Analyze or Cycle to get it.
Where can I do this and what kind of cell will they accept?
Mr Happy
Flashlight Enthusiast
Yes, you can. I have found the capacities reported by the break-in cycle to be quite repeatable and consistent. If one cell comes up low the first time round it will come up low the next time you test it too.
SilverFox
Flashaholic
Hello Pobox,
As far as recycling goes, here are some places that may take your cells.
There are a couple of ways to evaluate cells. One is to compare their capacity according to what is listed on the label. Another is to check them under the same loads you will be using them under. If you happen to know that your lights draw 1000 mA, then you can check your cells under a 1000 mA load.
Tom
As far as recycling goes, here are some places that may take your cells.
There are a couple of ways to evaluate cells. One is to compare their capacity according to what is listed on the label. Another is to check them under the same loads you will be using them under. If you happen to know that your lights draw 1000 mA, then you can check your cells under a 1000 mA load.
Tom
Handlobraesing
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That negates the theory that its method is IEC standard though. A standard is about running tests under same conditions and not about making the numbers look good.
So for a 2500mA cell, discharge current should be 500mA to 0.9v not an alternation of 1 second on and 1 second off at 1A as done by MH-C9000.
Alternating on 1 minute cycle instead would give the same time average current too, but I don't buy alternating between 1 minute at 1A and 1 minute at 0A as true 500mA.
I think even 0.5Hz is way too slow to claim the average as the true current. It's slower than car turn signals.
Then it can measure capacity just fine, however it doesn't serve its true purpose. Let's say you have a 2.5Ah cell that provides service at 100mA level. You couldn't care less about the voltage the cell can sustain at 1A.
If your purpose is to analyze the amount of usable capacity loss under the same rate found during service, MH-C9000 can falsely reject a cell as 0mAh because it can't hold >0.9v at 1A load.
