Hot Topics for New Owners

Q: I am seeing "Err3" at the end of the charge when charging my battery pack. Is this normal?

Err3 indicates a normal charging termination due to high temperature. It is the equivalence of a full charge. This is the MH-C777PLUS's way of telling you that it stopped charging because it sensed a temperature value which corresponded to full charge. This does not necessary imply overcharging. Err3 will appear more frequently especially if you are charging less than 3 battery cells (or battery pack 3.6V or less). When charging battery cells, they will appear to be somewhat warmer because they are not enclosed in a plastic case like other battery packs.

Q: I am charging a Lithium Ion battery pack. The charger seems to take very long (>10 hours) to fully charge my battery pack. Is this normal?

When operating in the Lithium Ion mode, the charging current is not constant. In fact, because Lithium Ion batteries are sensitive to overcharging, the MH-C777PLUS has been designed in such a way that the charging current is continuously decreased as the battery pack approaches full charge. Therefore, a significant portion (~95%) of the battery pack is fully charged in the first few hours. However, to finish up the final 5% of the battery pack, the charger does so at a much slower current, taking almost as much time to charge the remaining 5% of the battery pack as charging the 95%. The charger will not show full charge until the battery pack is 100% charged.

To illustrate, when charging a fully depleted 1200mAh Li-Ion battery pack, the accumulated charging capacity may be 300mAh at the first hour, 550mAh at the second hour, and 1150mAh at the fourth hour. However, the remaining 50mAh can take up as much as 3-5 hours to charge. Thus, the FULL charge symbol does not appear some 10 hours later. However, for all practical purposes, the battery pack is considered fully charged at 1150mAh. 

Therefore, when charging Lithium Ion battery packs, you can safely remove the battery pack (for all practical purposes, this is considered as a full charge) when the capacity on the screen is close to the rated capacity and when the capacity accumulation increases very slowly, even though the FULL symbol is not shown. 

Q: The battery pack seems to be hot after the charge. Is this normal?

Because the MH-C777PLUS is charging battery packs at a relatively high current, the battery pack is expected to increase in temperature during charging. The temperature can be as high as 131 degree F (55 deg C).

Q: The "charging capacity" is significantly higher than the rated capacity of the battery pack. Does this mean that the charger is overcharging my battery pack?

No. Battery pack charging capacity is generally higher than the actual capacity, sometimes up to 15%. This is a chemical property of the battery pack, as some of the energy inputted to the battery pack is lost as heat. To accurately measure the capacity of the battery pack, use the discharging capacity instead.

Q: I am charging a Lithium Ion battery pack and the charger display is switching between charging and standby and beeping like something is wrong. How can I fix this?

When you interrupt the charging of a Lithium Ion battery pack (including putting on and taking it off quickly when you are configuring the charging pins), the charger's self-logic will lock up. To fix this problem, simply reset the unit by unplugging the unit and plugging it back.

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Pre-sales / Basic Questions

Q: Explain the new "voltage detection algorithm" on the MH-C777PLUS.

The MH-C777PLUS features a new "voltage detection algorithm" that is designed to work properly even in the most abnormal conditions. The charger will apply a 3-minute "surface charge" prior to both charging and discharging. This surface charge is designed to give a voltage boost to the battery pack so that it can be recognized correctly. This feature is especially helpful for applications such as two-way radio where users often "over-drain" batteries below their nominal voltage.

Q: Explain the various techniques the MH-C777PLUS uses to determine when to terminate the rapid charging.

The MH-C777PLUS features three main sensors to determine if the battery pack is fully charged:

• Negative Delta Voltage: When a battery reaches full charge, its voltage will begin to drop. The charger has a highly sensitive circuit that will pickup the drop and terminate the charge.
  
  
• Zero Delta V: When a battery voltage does not change in a period of time, the charge will be terminated automatically.
  
  
• Maximum Temperature: The MH-C777PLUS features a temperature sensor that mounts externally to the battery pack. When temperature exceeds 51 degree Celsius or 123 degree F, the charge will be terminated.

Q: I will be traveling abroad. Does the MH-C777PLUS require additional transformers?

The standard power supply unit included with the MH-C777PLUS is a auto-switching travel adapter that will accept 80V to 240VAC 50/60Hz input. You can use this adapter almost in any AC power system, provided you have the proper adapter converter. No step-down transformer is needed.

Q: How long will the MH-C777PLUS take to charge my battery packs?

The charging time, which is different for each battery pack, is determined by dividing the capacity of the battery pack by the charging current. The capacity is given in "milliampere hours" and is generally found on the battery label. Take this number and divide it by the MH-C777PLUS charging current, which is 800mAh for NiMH & NiCD batteries and 400mA for Lithium Ion battery pack. The resulting value is the number of hours needed to quick charge the battery pack.

Q: How does the charger sense whether the battery pack is Lithium Ion or Nickel Metal Hydride?

The battery chemistry is selected via a "battery selector switch" on the MH-C777PLUS. Prior to the beginning of the charge, the user must make a proper selection.

Q: What is the maximum battery capacity supported by the MH-C777PLUS?

The charger has a safety timer at 13 hours. Therefore, the maximum supported capacity is 10400mAh. However, you can still charge battery packs with higher capacity: you need to charge the battery pack "twice" by restarting the charger after the safety timer expires.

Q: Can I charge a "9V-shape" battery pack or other capacity with capacity lower than 400mA?

It is highly not recommended to charge battery packs with capacity lower than 400mA, which includes "9V-shape" consumer batteries, due to the charger's rapid charging current at 800mA.

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Charging Individual Battery Cells

Q: How can I charge AA, AAA, C and D individual battery cells?

Using optional battery holders, you can charge AA, AAA, C and D individual battery cells. You can charge anywhere from 1 to 12 cells simultaneously. However, all the batteries being charged together must be similar in condition and specification.

Q: How many battery cells can I charge at the same time?

You can charge 1 to 12 battery cells simultaneously.

Q: Can I charge battery cells from different devices at the same time?

No. You must charge batteries from the same manufacturer and preferably used in the same device. In order to maximize battery life, it is important to charge batteries that have similar conditions.

Q:  Can I use the MAHA C-777 charger to recharge and condition individual 9 Volt NiMH / Nicad Batteries ?

No. The C777Plus II charger is not designed to recharge individual 9V NiMH or NiCD batteries. Although the MAHA C777Plus II is designed to handle most NiMH / NiCD batteries that fall between 4.8 and 13.6 volts,  it charges at too fast a rate for the small 9V batteries.  Please note that this applies only to the small  standard 9V batteries.  This has nothing to do with the fact that they are 9V batteries.  We have had several emails asking if the Maha C-777Plus II could be used to charge 9V ham radio packs because they read on our web site that the C-777Plus II should not be used to charge 9V Ham radio battery packs.  The answer is YES you can charge 9V packs but not the small 9V batteries.  

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Charging Battery Packs & LCD Display

Q: I am getting a continuous beeping when I place the battery pack on the charger. What is wrong?

If you are getting a continuous beep right after installing the battery pack on the charger, the polarity is incorrect. To resolve this issue, simply flip the "polarity switch" and the charge will begin.

Q: I am charging a Lithium Ion battery pack and the charger display is switching between charging and standby and beeping like something is wrong. How can I fix this?

When you interrupt the charging of a Lithium Ion battery pack (including putting on and taking it off quickly when you are configuring the charging pins), the charger's self-logic will lock up. To fix this problem, simply reset the unit by unplugging the unit and plugging it back.

Q: I am charging a Lithium Ion battery pack. The charger seems to take very long (>10 hours) to fully charge my battery pack. Is this normal?

When operating in the Lithium Ion mode, the charging current is not constant. In fact, because Lithium Ion batteries are sensitive to overcharging, the MH-C777PLUS has been designed in such a way that the charging current is continuously decreased as the battery pack approaches full charge. Therefore, a significant portion (~95%) of the battery pack is fully charged in the first few hours. However, to finish up the final 5% of the battery pack, the charger does so at a much slower current, taking almost as much time to charge the remaining 5% of the battery pack as charging the 95%. The charger will not show full charge until the battery pack is 100% charged.

To illustrate, when charging a fully depleted 1200mAh Li-Ion battery pack, the accumulated charging capacity may be 300mAh at the first hour, 550mAh at the second hour, and 1150mAh at the fourth hour. However, the remaining 50mAh can take up as much as 3-5 hours to charge. Thus, the FULL charge symbol does not appear some 10 hours later. However, for all practical purposes, the battery pack is considered fully charged at 1150mAh. 

Therefore, when charging Lithium Ion battery packs, you can safely remove the battery pack (for all practical purposes, this is considered as a full charge) when the capacity on the screen is close to the rated capacity and when the capacity accumulation increases very slowly, even though the FULL symbol is not shown. 

Q: The "charging capacity" at the end of the charge is significantly less than my battery pack's rating. Is this normal?

The final charging capacity refers to the total energy "absorbed" by the battery pack. Therefore, if the battery pack was not fully drained prior to charging, it cannot absorb as much energy as it is capable to. Charging capacity is more accurate when you charge a fully drained battery pack. However, for an accurate reference to the actual battery capacity, you should always refer to the discharging capacity. Another possibility for a low final charging capacity is that the battery pack is reaching the end of its useful life.

Q: In the first three minutes of the charge, the charging capacity seems to accumulate very rapidly. Then, after 3 minutes, the accumulated capacity resets to zero and restarts. Is this normal?

The first 3 minutes of both charging and discharging is the "surface charge" which is needed to properly detect the battery voltage. In the first three minute, the capacity on the screen may accumulate very rapidly. However, after the first 3-minute, the capacity will reset to zero and restart.

Q: When I place my diode-protected battery pack on the MH-C777PLUS, it takes very long for the charger to register the battery pack. Is this normal?

The charger has to charge up a capacitor circuit when sensing diode-protected battery packs. Therefore allow 3 to 15 seconds for the charger to register the battery pack if it is diode protected.

Q: The "charging capacity" is significantly higher than the rated capacity of the battery pack. Does this mean that the charger is overcharging my battery pack?

No. Battery pack's charging capacity is generally higher than the actual capacity, sometimes up to 15%. This is a chemical property of the battery pack.

Q: The battery pack feel quite warm after the charge. Is this normal?

Like any other rapid charger, temperature will rise substantially during a quick charge. The MH-C777PLUS is equipped with both voltage sensor and temperature sensor to prevent overcharge.

Q: I am seeing "Err3" at the end of the charge when charging my battery pack. Is this normal?

Err3 indicates a normal charging termination due to high temperature. It is the equivalence of a full charge. This is the MH-C777PLUS's way of telling you that it stopped charging because it sensed a temperature value which corresponded to full charge. This does not necessary imply overcharging. Err3 will appear more frequently especially if you are charging less than 3 battery cells (or battery pack 3.6V or less). When charging battery cells, they will appear to be somewhat warmer because they are not enclosed in a plastic case like other battery packs.

Q: Explain the various error codes: Err1, Err2, Err3 and Err5.

• Err1: Battery Fault. This generally indicates a reverse polarity. This issue may be resolved by flipping the polarity switch. This is accompanied by continuous beeps.
• Err2: Insufficient Input voltage. Make sure that the input voltage is high enough to charge your battery pack if you are using DC power sources other than the supplied AC adapter. Refer to the table below for minimal input voltage levels:

• Err3: High Temperature. This symbol indicates that the charger has terminated the charging due to high temperature. This is normal for certain batteries that produce more heat than others. This usually does not indicate a problem with the battery pack. Note: If you are charging 1 to 2 battery cells, the probability for Err3 to occur is higher.
• Err5: Battery pack detected during power on. This does not indicate a problem, but merely informs the user that a battery pack is connected when the charger powered up. It is recommended to disconnect any battery pack prior to powering the charger.

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Conditioning & Analyzing

Q: What is meant by "Conditioning" and "analyzing"?

Conditioning is a automatic cycle that first discharges the battery pack then charges it fully. Conditioning can be used to eliminate the memory effect which is common on NiCD battery packs. It also can be used to maintain Lithium Ion and NiMH battery packs. Another function of conditioning found on the MH-C777PLUS is its ability to "analyze" the battery pack. During discharging, the charger accumulates the capacity of the battery pack and digitally displays the capacity at the end of the discharge. This number determines the health of the battery pack.

Q: What is the difference between "Charging capacity" and "discharging capacity"? How should I interpret the "charging capacity" and "discharging capacity".

Charging capacity refers to the amount of the energy "absorbed" by the battery pack. However, this number does not imply the condition of the battery pack (meaning how long you can use it); instead, it merely indicates the progress of the charge. For example, a 1851mAh reading on the charging capacity display for a 2000mAh battery pack would indicate that the charge is approaching completion. The charging capacity, due to battery chemical properties, can be as high as 15% higher than the rated capacity.

On the other hand, "discharging capacity" refers to the actual energy "stored" in the battery pack. This number refers to how long the battery pack can last. If the final discharging capacity is close to the rated capacity of the battery pack, then the battery pack is in good condition.

Q: When I press the discharge button, it lasts only for about 3 minutes, then the charger goes to the charging mode. Why isn't the charger discharging my battery pack?

The first 3 minute of the discharging is the "surface charge" which is explained above. If after the first 3 minute, the discharging terminates and goes into charging, this means the battery pack could not be discharged due to a diode protection. Diode-protected terminals, which are generally referred to as the "drop-in charging terminals" can be used for charging but not discharging. To resolve the issue, you should use the "discharging contacts", metal plates that your device uses to drain power. On a two-way radio, for example, the discharging contacts are the radio-end contacts.

Q: My charger will not properly discharge a 1 cell or 2 cell battery pack. Is this normal?

The MH-C777PLUS will not discharge 1 or 2 cell batteries (or battery pack 2.4V and less).

Q: After the discharging is finished, what happens?

Discharging is part of the "conditioning cycle" which will first discharge the battery pack then rapid charge it completely. After discharging is finished, the charger will sound loud beeps to let you know discharging is done. The final discharging capacity will be retained on the screen for 15 minutes. After that, the MH-C777PLUS will automatically start the charging cycle. None of this will require user-intervention.

Car Operations

Q: What is the limitation when using the MH-C777PLUS in a car? What precautions should I be aware of when using the unit in a car?

When using the MH-C777PLUS on a 13.8VDC power supply (such as a car), the voltage range supported will be reduced to 1.2V to 4.8V for NiMH and NiCD battery packs and 3.6V to 7.2V for Lithium Ion battery packs.

When powering the unit using vehicular power, make sure that the charger is disconnected when starting the vehicle. Failure to do so may permanently damage the charger.