There are many factors that determine the type of charger required for a particular application.
Choosing the right charger is very important to insure not only all requirements are met but also the charger is not over specified resulting in a more costly solution than required.
1. Input AC voltage range:
Will the charger be operating from 110VAC, 220VAC or 440VAC ? "KONGU ENGINEERS" offers units in all input ranges.
2. Number of batteries required to be charged:
How many batteries are required to be charged? Is it possible to save cost by using a multi-bank charger as opposed to a single output unit. For example, consider a 24V system comprised of two 12V batteries in series. The entire battery pack can be charged with a single 24V unit.
3. Type of battery chemistry:
"KONGU ENGINEERS" offer chargers for several battery chemistries. While the standard units are lead-acid types, "KONGU ENGINEERS" has the capabilities do custom applications for other chemistries such as Lithium Ion, Ni-Cd, Ni-MH, etc.
4. Depth of Discharge:
Is your application one where the battery is only moderately used or will it undergo deep discharges. Is it heavily discharged infrequently or very often? Is there a requirement to charge quickly or is there "plenty of time". The following procedure will provide a good rule of thumb in determining your charger requirements:
(a). Calculate the amount of drain on the battery in terms of amp hours. For example, if your battery is providing 10 amps for 3 hours this is equal to 30 amp hours (number of amps multiplied by number of hours) Similarly, 3 amps for 10 hours is also 30 Amp hours. (For a more exact calculation, refer to the discharge curves of the Battery manufacturer's specification where discharge time as a function of current is provided.)
(b). Now that the number of amp hours is calculated, divide this amount by the number of hours you have available to charge to determine charging current. For example, if you have only six hours to charge, you will require a 6 amp charger (30 amp hours divided by 6 hours = 5 Amps.)
(c). Multiply the number obtained in (b) by 1.2 to provide for charge acceptance and energy lost during charging: (5 Amps * 1.2= 6 Amps)
(d). Now check the battery specification to insure that the battery can accept 6 amps and charge effectively. If not, the recharge time you allowed will have to be increased.
5. Is a maintenance or three-state charger required?
Maintenance Use: Will the charger be used to maintain the charge on a battery, a maintenance charger can be used for these types of applications.
Three State Charger: If the charger will be the primary charger for the battery then the three state charger is what you need. This will return 100% capacity every time and reduce the voltage when complete to maintain the battery at full capacity indefinitely.
6. Voltage Rating:
The battery must have the proper charging voltage applied. For example, it is acceptable to apply a 12V charger to two 6V batteries in series since this equals 12V but not to use the charger to charge the batteries individually.
7. Charging Current
The charging current is one of the most important criteria in choosing a charger. An excessive amount of current will overheat the battery resulting in reduced battery life and poor capacity. Some batteries are able to accept very large charging currents while others are more sensitive. You must check your battery specification to insure that you are not applying current in excess of the recommended amount.
