The proper care of batteries in portable handheld radio system is typically the most significant problem experienced by the users of two-way radio systems. Proper procedures with significantly extend battery life while improper procedures will result in premature battery failure necessitating replacement of the battery at significant expense. Therefore, following the proper procedures will result in significant cost savings over the lift of the radio system.
There are four different battery chemistries in use today. Three of them are in current used for new equipment and one is an older technology used in legacy radios. These are:
|Battery Chemistry Name||Abbr.||Pronounced|
|Nickel Metal Hydride||Ni-Mh||“Nimhh”|
Nickel Cadmium is the oldest of the battery technologies. Current production radio equipment does not use Ni-Cd batteries, but they exist in many older legacy radio systems. The battery is becoming far less popular due to the Ni-Cd memory effect which is very pronounced with these batteries. When you use 40% of the battery capacity repeatedly, eventually the battery only has 40% of its original capacity. There is some ability to recover some of the capacity through conditioners, but it generally will never recover 100% of the original capacity.
Nickel Metal Hydride is a better battery chemistry which has replaced most Nickel Cadmium batteries in legacy radios. Ni-Mh batteries do not develop the deep battery memory like Ni-Cd batteries, but we find that they will also do it to some extent. They are more tolerant of abuse than Ni-Cd batteries. They tend to be heavy batteries which is an undesirable feature.
Lithium Ion battery is the current and most popular battery chemistry in use today. They do not tend to develop memory and they are extremely light weight, thus making them a better battery technology.
Lithium Polymer battery is the newest battery chemistry to arrive on the market. The lithium polymer battery gives the greatest battery capacity per weight and size than any of the other battery chemistries and tends to be the most expensive.
All batteries are rated for capacity in terms of how much current the radio can supply for a period of time. The unit of measure is amp-hours which are used for larger batteries such as car batteries and batteries for UPS systems that keep your computers working during power outages that last about 15-45 minutes. Fifteen amp-hours is a battery that can supply 7.5 amp of current for two hours. Batteries for portable radios are measured in smaller units which are milliamp-hours. An example of this is a medium duty battery for the Kenwood NX-300 portable radio which is 2550 mAh (or milliamp-hour) and will provide 255 milliamps for 10 hours. Therefore, you cannot tell how long the battery will last unless you know the capacity of the battery and the amount of power that is drawn by the load that is being powered by the battery.
Radios do not use the same amount of current for all operations. As an example, a radio may use 15 milliamps during standby which is when the radio is turned on and waiting for someone to call, but no one is talking. The same radio will use anywhere from 50 milliamps to 150 milliamps depending upon the setting of the volume control while it is receiving a transmission. When the transmit button is depressed, the same radio will draw between 750 milliamps to 2000 milliamps depending upon the output power of the radio. Therefore, a small amount of talking time equals a lot of listening time and even more standby time.
Batteries for portable radios are rated by the ratios of time that the battery is used for the different functions. The two most common ratings for battery comparison are:
- 5-5-90 5% transmit, 5% receive, 90% standby
- 10-10-80 10% transmit, 10% receive, 80% standby
Therefore, when you compare battery life of radios, you need to know which one of the scales are used and compare batteries on the same scale.
There are several types of chargers for batteries. They start with trickle chargers that charge the battery very slowly. These are the most economical chargers, but they can easily ruin a battery if you do not take care to remove the battery from charge when it is fully charged. Rapid chargers are the most popular type of battery charger which will charge the battery rapidly until it is typically 80% charged, then switch to a slower charge to finish the charge cycle. Once the battery is fully charged, the charger typically switches again to a trickle charge.
There is a third type of battery charger that is used in the more expensive radio systems, typically when the user of the radios had hundred or thousands of radios. These batteries have a computer chip inside the battery pack that stores information about the condition of the battery, how many times it has been charged, the serial number of the battery, who is using the battery, its current charge level, its current capacity compared to when it was new, etc. When you place the battery in a compatible “smart” charger, the battery information is transferred to the charger which is connected to a computer LAN. The battery and charger both communicate with a central computer that keeps track of these parameters so that the health of the batteries for the entire system can be monitored from a single location. This eliminates the biggest problem in portable radio systems.
Each type of battery requires a different method to charge the battery. There are many “smart” chargers on the market that detect the type of battery chemistry and automatically adjust their charging method for the type of battery in the charger. Most chargers will charge Ni-Cd and Ni-Mh batteries. Some chargers with charge Ni-Cd, Ni-Mh, Li and Li-Po batteries. Some chargers will only charge a single battery chemistry. Therefore, you should make certain that you have the correct type of charger for your application and battery type.
Battery Charging Instructions
Each battery manufacturer and battery charger manufacturer will design their battery and charger differently than another manufacturer. The procedure described herein is for a typical Kenwood rapid charger. The following is the best procedure to follow when charging and storing batteries:
- Turn off the radio
- Make certain that the battery contacts are clean and unobstructed by tape or any other material. Clean contacts if necessary due to grease, grime or goo on the battery before you place in the charger.
- Most battery chargers will allow charging of the battery either by itself or while attached to the radio. If you charger is designed for only one of these methods, use the appropriate method for your charger.
- Insert the radio into the battery charger with the battery still attached. Some batteries have grooves on the side of the battery to keep the battery aligned with the battery contacts so that it will charge with or without a battery. Make certain that if your battery does have the grooves, you align the grooves of the battery with the protrusions in the charger so that the battery properly sits in the charger pocket and engages with the charger.
- The charger LED will turn on RED to indicate that it is charging. The charger analyzes the state of the battery and will do one of the following:
- Stay RED and continue to charge the battery.
- Flash RED to indicate that the charger thinks the battery has some issue. Typically, it means that the battery is faulty. Sometimes you can “clear” the fault by removing and reinserting the battery. If that does not clear the fault, try using another battery charger to see if the other charger agrees. If multiple chargers indicate a fault, it is time to replace the battery.
- Turn GREEN when the rapid charging is complete.
- When the LED turns green, it is OK to leave the battery in the charger for a while, typically overnight or over a weekend.
- Do not leave batteries in the charger for extended periods of time such as while on vacation for weeks, summer breaks or continuously. It is only likely to ruin the battery.
- Batteries will discharge by themselves, typically at a rate of 2% per month if it is a healthy battery. If the battery has developed internal leakage, it can discharge by up to 20% per day or more depending upon how much internal leakage is in the battery.
- When a battery is charged and attached to a radio that is turned off, the battery will discharge by itself over time. Most radios still draw a small amount of energy from the battery when turned off, so the longer the battery sits, the more it will be drained. Different models of radios act differently, so there is no universal number, but you can expect a healthy battery attached to a good radio to discharge at the rate of 3% per month or more while not in use. Therefore, for extended storage, it is better to disconnect the battery from the radio.
- It is best to never fully discharge a battery. Some batteries will never recover fully when the battery is drained completely. Most radios will stop working well before the battery is fully discharged. If you leave a radio turned on for extended periods, it will drain the battery to the point where the radio stops working and continue to drain the battery until it eventually goes to zero volts. At that point, the battery is unlikely to recover when charged. If the battery is charged well before it gets to zero volts, it may mostly or fully recover.
- Batteries should be fully charged as soon as possible after being discharged. The longer you wait to charge the battery when it is fully discharged, the greater the likelihood that the battery will be damaged.
- New batteries come with a “dry” charge which is OK to store for reasonable periods of time, typically 1-2 years. After that, the battery should be charged to sit on the shelf.
- Once a battery has been placed into service, the battery should be stored in the fully charged condition
I hope that this discussion of battery treatment is informative and will help you get maximum performance from your fleet of batteries.