After the appearance of the Ni-Cd (nickel-cadmium) batteries in the late 1970s and early 1980s, many senior players realized that the rechargeable battery has a unique “personality”. In order to obtain the highest performance and longest life, rechargeable batteries must be charged in a specific way. Whenever a new battery launched, a difficult task is to identify its characteristics, and then to find the means which can obtain the best results.
Later, NiMH battery (nickel-metal hydride batteries, also called green battery) was born, which have ranged from 3000mAh to 3300 to 3600, 3800, 4200 recently. NiMh battery capacity and performance are constantly leap pushing the car to achieve a more alarming rate and longer discharge time. However, due to the inherent characteristics of NiMH battery, rechargeable batteries of different capacities and maintenance processes are in similarity. Below here we look at each common charging problems.
Please note: we are talking about the values are based on ordinary tenth tram power batteries, namely the size of Sub-C.
1; With how much amperage to charge?
In the era of Ni-Cd, we typically charge with the twice capacity value of the battery, such as a battery which is 1800mAh (mAh: mA * h); 1.8 multiplied by 2 is 3.6 , then with 3-4 amperes is safe to charge , and the charge is relatively full. For NiMh battery, this law basically applies. larger capacity battery can be charged with a higher current, but the factor should be kept. Generally speaking, 5 amps is a good start value, then we can try to improve the current, such as 5.5 amps, 6 amps, installed in the car running, to feel about what is the difference; in the end you can find a suitable current value. Typically, the current is high, the battery will be stronger and more explosive, but may be not full as the current lows. Please note: the high current, such as 8, 9A, may be unable to improve performance, even to damage your battery. Recommended between 4.0 to 6.5 amps.
The basic rules: charge too full, but do not damage the battery.
Almost all of the type of the “peak detection” charger can be used to charge the NiMH battery. However, please be careful not to use unspecifically designed for NiMH charger. Peak detection is by detecting the amount of the charger voltage drop to indicate that the battery capacity has reached maximum. When Ni-Cd batteries are in the charging process, the voltage fluctuation is larger, and in the last paragraph of the charging voltage drop is also larger. While the NiMH battery voltage during the charging process is more stable, lower volatility, the time to reach the maximum capacity of the voltage drop is also smaller. So, the charge designed for the Ni-Cd battery willnot stop charging until the battery produces relatively large voltage, so to use this charger will cause over-charging. So, do not buy some relatively cheap, but can not adjust the value of the peak detection charger.
3; How much detect peak should be used?
If your detect peak of charger is adjustable, then the best set is from 0.02 to 0.03 volts (for whole row 6 batteries). The drop of the voltage detected by charger can trigger to stop the charging. With a smaller value, such as 0.01 volts, the charge often have better results, but for some with the not so good performance, this low value may cause a “false charge full” phenomenon.
That is some normal voltage fluctuations, triggered stop charging.g.
Temperature sensor control: Some chargers have a temperature sensing probe. NiMH battery’s probe will be hotter than the Ni-Cd’s when the formmer reaches to maximum capacity. For the excellent performance of batteries, Ni-Cd is in 35 to 37 degrees, while NiMH 40-45 degrees. Remember, this is the probe readings rather than the feeling of your hand feels. Temperature sensor detection is a good supplement to peak detection. It is sensitive to temperature changes of the battery, to help determine whether the battery reaches maximum capacity, avoiding overheating while charging the battery and damage the battery at the same time.
4; With what mode to charge?
Chargers have many models to choose. Some models are specifically designed to increase the performance of Ni-Cd batteries, but it will damage the NiMH batteries itself. No matter what brand of chargers, NiMH batteries should be charged with “linear” mode (Linear). The current process of linear mode will not be inverted by the fluctuation control, or polarity in the charging process. Occasionally to charge NiMH batteries in the wrong mode will not have any major impact on the discharge time, but will reduce the battery voltage.
Basic rules: using a linear model to charge. This is the only mode the default mode for the vast majority of high-grade and low-grade charger charger.
5; Will the trickle charging harm NiMH battery?
Trickle charge (Trickle Charging) should be avoided to be used in the NiMh batteries. Some quick charger after charging, then trickle charging. This model is for a Ni-Cd battery, making it maintain the highest voltage between the time from the full power to the little period to be used, but this pattern is unfavorable for NiMH batteries. We should set the charger drip mode to “off” state, if it can not be set, then when the battery is full, disconnect it from the charger immediately.
When you do not use a fully charged battery for an extended length of time (even a few days), its internal resistance increases, resulting in a loss of punch and capacity. However, this becomes most significant when storing for a week or more. To prevent battery damage, when storing do not fully charge a battery. Charging it to about 80-85% is best for the battery and will result in a greatly reduced rate of aging. Also, storing batteries in the REFRIGERATOR will help to reduce the effects of storing (assuming your fridge doesn’t freeze the milk all the time).
This should have you thinking that if you fly your electric RC helicopter or plane in the winter time, you might keep your RC battery in a more proper way.