(Precautions on charging)
1. As the battery continues to be charged over a long period, a small difference in charging voltage may result in a significant difference in the battery life.
Therefore, charge voltage should be controlled within a narrow range and with little variation for a long period.
2. As charge characteristics of the battery are dependent on temperature, compensation for temperature variation is required when the battery is used over a broad temperature range, and the system should be
designed so that the battery and the charger are kept at the same temperature.
Float charging
Float system is the system in which the battery and the load are connected in parallel to the rectifier, which should supply a constant-voltage current.
In the above-illustrated model, output current of the rectifier is expressed as:
lo = lc + lL where lc is charge current and lL is load
current. Consideration should be given to secure adequate charging because, in fact, load current is
not constant but irregular in most cases.
In the float system, capacity of the constant-voltage power source should be more than sufficient against the load. Usually, the rectifier capacity is set at the sum of the normal load current plus the current needed in order to charge the battery.
