SilverFox
Flashaholic
Wow!!! This is the charger/analyzer we have been hoping for.
Maha has stepped up to the line with a charger that offers a wide variety of charge rates, and also offers cycling, refreshing, and discharging at a wide variety of rates. It directly supports AA and AAA sized batteries, and charges/discharges/analyzes each of its four slots independently. The large lighted display is easy to read and gives you the information for each slot, one slot at a time. The buttons are well spaced and have a good "feel" to them. There is ample space between the cells so it is easy to remove and replace a cell, even if it is in a middle slot. The large backlit LCD display and the extra space between cells make the C9000 larger than most other four cell chargers, but it also has a more complete "feature set" than any other consumer charger on the market. It is suitable for charging NiMh and NiCd cells, including the new "low self discharge rate" cells.
One of the most important and beneficial features of the C9000 is the Break-In mode. Battery manufacturers rate their battery capacity and cycle life using a "standard" charge and a "standard discharge." The C9000's Break-In mode allows you to compare your batteries performance to what they are supposed to be. This allows you to know the condition of your batteries, and to compare various brands of batteries.
Sometimes batteries that have been abused or left in storage for an extended period of time can be brought back to life by a Break-In cycle. It doesn't always work, but since it is an automatic function on the C9000, it's worth a try.
Well, it's not completely automated. It's best to start with a discharge battery, so you may have to do a discharge first and then run the Break-In. Most cells should be able to handle the low charge rate of the Break-In mode without problems, but some cells have a higher internal resistance and they tend to heat up a lot when overcharged. Starting with a discharged cell eliminates the overcharge heating.
Keep in mind that the "standard" charge involves charging a cell at rate equal to one tenth of its labeled capacity for 16 hours. In the Break-In mode, this "standard" charge is followed by a one hour rest period, then the cell is discharged over five hours. After another rest period, another "standard" charge is done on the cell. Doing the math we come up with a 16 hour charge + 1 hour rest + 5 hour discharge + 1 hour rest + 16 hour charge = 39 hours.
39 hours seems like a long time to tie up your charger, but your cells will love you for it. Since it requires no input from you, other than selecting the mAh capacity of your cell when you start, you can just set it and leave it.
Those who can figure out a way to charge C and D sized cells external of the C9000 can use the Break-In mode for those cells as well. The maximum capacity for the C9000 in Break-In mode is 20000 mAh. Understand that these larger capacity cells will take longer to complete the Break-In than AA cells.
The alternative is to do several cycles. The C9000 allows you to program up to 12 cycles and allows you to set the charge and discharge rates for the cycling. It also stores the capacity data so you can review it and see what effect cycling is having. The default charge rate is 1000 mA and the default discharge rate is 500 mA in Cycle mode.
These features alone make it worth having this charger, but there is more…
The C9000 has a discharge only mode.
Have you ever wondered how much capacity you loose with your cells sitting on the shelf for a week or so? It is often widely stated that NiMh cells will loose almost all of their capacity in a very short time, however with the discharge mode of the C9000 you can put those reports to bed and know that is not the case. With the introduction of the new low self discharge rate batteries like the Sanyo Eneloop cells, you can also check to see if they are holding up to their claims. You can also determine how much of an improvement a higher capacity battery offers.
You can even check out the various brands of Alkaline cells to see which offers the highest capacity for the discharge rate you are interested in. The C9000 will not charge Alkaline cells, but it does allow you to do a discharge on them. Ever wonder how much better a Lithium primary cell is than an Alkaline cell? Now you can check it out for yourself.
The discharge mode defaults at 500 mA, but allows you to select a discharge rate from 100 mA to 1000 mA, in 100 mA steps. It continues until the cell reaches 0.9 volts and the display shows the capacity in mAh, the voltage of the cell, and the time involved with the discharge. This information is displayed until the cell is removed.
In multi cell applications, your device will stop working when the lowest capacity cell runs out. To get the best performance in multi cell applications, you need to match your cells on capacity. This way they all run out at the same time. The discharge mode of the C9000 allows you to do this.
Make sure you also get the 12 volt adaptor cord for the C9000. In many parts of the world there are times when an emergency occurs and the power goes out. During an extended power outage the C9000's ability to operate from 12 volts gives you the ability to recharge batteries when the main power is out.
The AC adapter for the C9000 works worldwide accepting 100-240 volts 50/60 Hz input.
Now that we have worked our way through all of the "bonus" features of this charger, let's take a look at how it charges.
To charge your batteries, insert them in the charger and take them out when "Done" is displayed.
If you are interested in a "fuller" charge, wait two hours after "Done" for the top off charge to complete.
That's it.
Can it really be that simple? YES!!!
As cells age their internal resistance increases. The C9000 checks for this and will display "HIGH" if the internal resistance is increased to the point that it is not healthy enough for high rate charging.
If you get the "HIGH" message, recycle the cell and move on.
Now if great grandfather gave you that cell and you just can't stand to part with it, there are a few things you can do. Hold it in your hand to warm it up. Internal resistance goes down with heat. A discharge at a higher rate will also warm the cell up. If that does not work, you will have to use a charger that does not check for internal resistance, but don't expect to get peak performance from it. If it does start to charge, do a Break-In on it and explain to great grandfather that this battery may die before he does…
The C9000 has a default charge rate of 1000 mA. This charge rate works great for all AA cells and also is well suited for AAA cells. It may be a little high for some of the older low capacity (600 mAh) AAA cells, but if the cell is in good condition, it will do fine at the default rate.
If you don't like the default settings, and think you know something about battery charging, the C9000 allows you to select a charging rate from 200 mA up to 2000 mA in 100 mA steps. The NiMh battery manufacturers recommend charging at a 0.5C to 1.0C charge rate to insure a strong "end of charge" signal. C refers to the labeled capacity of the battery. If we had a 2000 mAh battery, a 0.5C charging rate would be 1000 mA, and a 1C charging rate would be 2000 mA.
So, what happens if you want to charge everything at 200 mA?
Well, first of all, it takes longer, and secondly, the end of charge signal may be too weak for the charger to recognize it and terminate the charge. This will result in overcharging the cell. The C9000 will "time out" at 4000 mAh, but it is probably better to set a timer and manually check to see if the charger missed the termination signal. If it did, you can manually shut it off. I have charged a wide variety of brands and capacities of both AA and AAA cells at 200 mA and have not had a missed termination, but my sample is too small to make a broad statement. Usually the C9000 will properly terminate, but I am sure there will be some cases where it will continue to charge at this low rate until it "times out."
At the other end of the spectrum is charging everything at 2000 mA. When charging four AA cells at 2000 mA, the C9000 heats up. This heat is radiated to the cells that are charging, and they heat up as well. The amount the cells heat up is dependent on their internal resistance and general condition.
Here are some actual test results while charging 4 cells at 2000 mA:
AAA 850 mAh cells got up to 118 F. These cells were not in very good condition.
AAA 900 mAh cells got up to 115 F. These were in pretty good condition.
AAA 700 mAh cells got up to 112 F. These are old, well used cells.
AA 2300 mAh cells got up to 130 F. These are well used cells that have a slightly increased internal resistance.
AA 1800 mAh cells got up to 112 F. These cells are designed for high current and have very low internal resistance.
AA 2500 mAh cells got up to 125 F. These are new cells in good condition.
AA 2600 mAh cells got up to 137 F at mid cell and 135 F at the negative end where the C9000 monitors the cell temperature. These are also new cells, but they have high internal resistance and are not suited to high charge rates, or high discharge rates. At high charge and discharge rates, they heat up.
AA 2650 mAh cells got up to 128 F. These are new cells with moderate use.
AA 2600 mAh cells got up to 129 F. These are older cells with hard use.
Keep in mind that these are the peak temperatures that occurred during the last stage of the charge. The temperature actually peaks a few moments after the charge terminates. The cell temperatures during the bulk of the charge were in the 95 – 100 F range.
The C9000 monitors the temperature of each battery slot and terminates the charge if the cell temperature (measured at the negative end of the cell) exceeds around 135 F. There is no alarm indication when a cell terminates on high temperature. The C9000 simply terminates the charge and displays "Done" along with the charge time and mAh put into the cell.
The C9000 utilizes a very tight battery holder. A good connection is required for high rate charging. I have found that the easiest way to insert cells is to put the negative end in first and snap in the positive end. To remove the cell, press back to compress the spring at the negative end and tip the cell out positive end first.
The C9000 is about 6.5 inches tall, 4.5 inches wide and 1.5 inches thick. It has a lift rod that raises the back of the charger up for easier viewing and better air circulation. The power adaptor is roughly 2.875 inches tall, 1.875 inches wide, and 1.5 inches deep, not including the prongs that plug in.
A top off charge of 100 mA is applied at the end of the charge cycle for two hours. After that, a maintenance charge of 10 mA is applied for as long as the battery is in the slot.
Maha has a three year warranty on the C9000. To view more information on this excellent charger and to check out the owners manual, visit www.mahaenergy.com .
The C9000 was released in late December 2006. Early units had some difficulty terminating with a few cells, especially at lower charge rates. This review was done on a C9000 received in February 2007, and reflects improvements Maha has made to the charge algorithm.
Another big "thumbs up" to Maha. This is an excellent charger/analyzer. Simple enough for casual use, but offering advanced, sophisticated features for those times when we are trying to better understand the condition of our batteries, or when we are matching cells for multi cell use.
Tom
Maha has stepped up to the line with a charger that offers a wide variety of charge rates, and also offers cycling, refreshing, and discharging at a wide variety of rates. It directly supports AA and AAA sized batteries, and charges/discharges/analyzes each of its four slots independently. The large lighted display is easy to read and gives you the information for each slot, one slot at a time. The buttons are well spaced and have a good "feel" to them. There is ample space between the cells so it is easy to remove and replace a cell, even if it is in a middle slot. The large backlit LCD display and the extra space between cells make the C9000 larger than most other four cell chargers, but it also has a more complete "feature set" than any other consumer charger on the market. It is suitable for charging NiMh and NiCd cells, including the new "low self discharge rate" cells.
One of the most important and beneficial features of the C9000 is the Break-In mode. Battery manufacturers rate their battery capacity and cycle life using a "standard" charge and a "standard discharge." The C9000's Break-In mode allows you to compare your batteries performance to what they are supposed to be. This allows you to know the condition of your batteries, and to compare various brands of batteries.
Sometimes batteries that have been abused or left in storage for an extended period of time can be brought back to life by a Break-In cycle. It doesn't always work, but since it is an automatic function on the C9000, it's worth a try.
Well, it's not completely automated. It's best to start with a discharge battery, so you may have to do a discharge first and then run the Break-In. Most cells should be able to handle the low charge rate of the Break-In mode without problems, but some cells have a higher internal resistance and they tend to heat up a lot when overcharged. Starting with a discharged cell eliminates the overcharge heating.
Keep in mind that the "standard" charge involves charging a cell at rate equal to one tenth of its labeled capacity for 16 hours. In the Break-In mode, this "standard" charge is followed by a one hour rest period, then the cell is discharged over five hours. After another rest period, another "standard" charge is done on the cell. Doing the math we come up with a 16 hour charge + 1 hour rest + 5 hour discharge + 1 hour rest + 16 hour charge = 39 hours.
39 hours seems like a long time to tie up your charger, but your cells will love you for it. Since it requires no input from you, other than selecting the mAh capacity of your cell when you start, you can just set it and leave it.
Those who can figure out a way to charge C and D sized cells external of the C9000 can use the Break-In mode for those cells as well. The maximum capacity for the C9000 in Break-In mode is 20000 mAh. Understand that these larger capacity cells will take longer to complete the Break-In than AA cells.
The alternative is to do several cycles. The C9000 allows you to program up to 12 cycles and allows you to set the charge and discharge rates for the cycling. It also stores the capacity data so you can review it and see what effect cycling is having. The default charge rate is 1000 mA and the default discharge rate is 500 mA in Cycle mode.
These features alone make it worth having this charger, but there is more…
The C9000 has a discharge only mode.
Have you ever wondered how much capacity you loose with your cells sitting on the shelf for a week or so? It is often widely stated that NiMh cells will loose almost all of their capacity in a very short time, however with the discharge mode of the C9000 you can put those reports to bed and know that is not the case. With the introduction of the new low self discharge rate batteries like the Sanyo Eneloop cells, you can also check to see if they are holding up to their claims. You can also determine how much of an improvement a higher capacity battery offers.
You can even check out the various brands of Alkaline cells to see which offers the highest capacity for the discharge rate you are interested in. The C9000 will not charge Alkaline cells, but it does allow you to do a discharge on them. Ever wonder how much better a Lithium primary cell is than an Alkaline cell? Now you can check it out for yourself.
The discharge mode defaults at 500 mA, but allows you to select a discharge rate from 100 mA to 1000 mA, in 100 mA steps. It continues until the cell reaches 0.9 volts and the display shows the capacity in mAh, the voltage of the cell, and the time involved with the discharge. This information is displayed until the cell is removed.
In multi cell applications, your device will stop working when the lowest capacity cell runs out. To get the best performance in multi cell applications, you need to match your cells on capacity. This way they all run out at the same time. The discharge mode of the C9000 allows you to do this.
Make sure you also get the 12 volt adaptor cord for the C9000. In many parts of the world there are times when an emergency occurs and the power goes out. During an extended power outage the C9000's ability to operate from 12 volts gives you the ability to recharge batteries when the main power is out.
The AC adapter for the C9000 works worldwide accepting 100-240 volts 50/60 Hz input.
Now that we have worked our way through all of the "bonus" features of this charger, let's take a look at how it charges.
To charge your batteries, insert them in the charger and take them out when "Done" is displayed.
If you are interested in a "fuller" charge, wait two hours after "Done" for the top off charge to complete.
That's it.
Can it really be that simple? YES!!!
As cells age their internal resistance increases. The C9000 checks for this and will display "HIGH" if the internal resistance is increased to the point that it is not healthy enough for high rate charging.
If you get the "HIGH" message, recycle the cell and move on.
Now if great grandfather gave you that cell and you just can't stand to part with it, there are a few things you can do. Hold it in your hand to warm it up. Internal resistance goes down with heat. A discharge at a higher rate will also warm the cell up. If that does not work, you will have to use a charger that does not check for internal resistance, but don't expect to get peak performance from it. If it does start to charge, do a Break-In on it and explain to great grandfather that this battery may die before he does…
The C9000 has a default charge rate of 1000 mA. This charge rate works great for all AA cells and also is well suited for AAA cells. It may be a little high for some of the older low capacity (600 mAh) AAA cells, but if the cell is in good condition, it will do fine at the default rate.
If you don't like the default settings, and think you know something about battery charging, the C9000 allows you to select a charging rate from 200 mA up to 2000 mA in 100 mA steps. The NiMh battery manufacturers recommend charging at a 0.5C to 1.0C charge rate to insure a strong "end of charge" signal. C refers to the labeled capacity of the battery. If we had a 2000 mAh battery, a 0.5C charging rate would be 1000 mA, and a 1C charging rate would be 2000 mA.
So, what happens if you want to charge everything at 200 mA?
Well, first of all, it takes longer, and secondly, the end of charge signal may be too weak for the charger to recognize it and terminate the charge. This will result in overcharging the cell. The C9000 will "time out" at 4000 mAh, but it is probably better to set a timer and manually check to see if the charger missed the termination signal. If it did, you can manually shut it off. I have charged a wide variety of brands and capacities of both AA and AAA cells at 200 mA and have not had a missed termination, but my sample is too small to make a broad statement. Usually the C9000 will properly terminate, but I am sure there will be some cases where it will continue to charge at this low rate until it "times out."
At the other end of the spectrum is charging everything at 2000 mA. When charging four AA cells at 2000 mA, the C9000 heats up. This heat is radiated to the cells that are charging, and they heat up as well. The amount the cells heat up is dependent on their internal resistance and general condition.
Here are some actual test results while charging 4 cells at 2000 mA:
AAA 850 mAh cells got up to 118 F. These cells were not in very good condition.
AAA 900 mAh cells got up to 115 F. These were in pretty good condition.
AAA 700 mAh cells got up to 112 F. These are old, well used cells.
AA 2300 mAh cells got up to 130 F. These are well used cells that have a slightly increased internal resistance.
AA 1800 mAh cells got up to 112 F. These cells are designed for high current and have very low internal resistance.
AA 2500 mAh cells got up to 125 F. These are new cells in good condition.
AA 2600 mAh cells got up to 137 F at mid cell and 135 F at the negative end where the C9000 monitors the cell temperature. These are also new cells, but they have high internal resistance and are not suited to high charge rates, or high discharge rates. At high charge and discharge rates, they heat up.
AA 2650 mAh cells got up to 128 F. These are new cells with moderate use.
AA 2600 mAh cells got up to 129 F. These are older cells with hard use.
Keep in mind that these are the peak temperatures that occurred during the last stage of the charge. The temperature actually peaks a few moments after the charge terminates. The cell temperatures during the bulk of the charge were in the 95 – 100 F range.
The C9000 monitors the temperature of each battery slot and terminates the charge if the cell temperature (measured at the negative end of the cell) exceeds around 135 F. There is no alarm indication when a cell terminates on high temperature. The C9000 simply terminates the charge and displays "Done" along with the charge time and mAh put into the cell.
The C9000 utilizes a very tight battery holder. A good connection is required for high rate charging. I have found that the easiest way to insert cells is to put the negative end in first and snap in the positive end. To remove the cell, press back to compress the spring at the negative end and tip the cell out positive end first.
The C9000 is about 6.5 inches tall, 4.5 inches wide and 1.5 inches thick. It has a lift rod that raises the back of the charger up for easier viewing and better air circulation. The power adaptor is roughly 2.875 inches tall, 1.875 inches wide, and 1.5 inches deep, not including the prongs that plug in.
A top off charge of 100 mA is applied at the end of the charge cycle for two hours. After that, a maintenance charge of 10 mA is applied for as long as the battery is in the slot.
Maha has a three year warranty on the C9000. To view more information on this excellent charger and to check out the owners manual, visit www.mahaenergy.com .
The C9000 was released in late December 2006. Early units had some difficulty terminating with a few cells, especially at lower charge rates. This review was done on a C9000 received in February 2007, and reflects improvements Maha has made to the charge algorithm.
Another big "thumbs up" to Maha. This is an excellent charger/analyzer. Simple enough for casual use, but offering advanced, sophisticated features for those times when we are trying to better understand the condition of our batteries, or when we are matching cells for multi cell use.
Tom
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