Micropower’s product range includes everything from simple unregulated Wa chargers to computer-controlled thyristor or transistor-regulated 50Hz or HF chargers. The choice of charger is based on the type of battery, area of use and charging time.
When charging a freely ventilated lead battery at normal temperature and charging depth and an available charging time of 8-14 hours, a simpler Wa charger like the STC is quite sufficient.
Charging batteries in 2-3 shifts, with or without acid circulation and a short charging time, however, requires a regulated charger, for example the MTM or the MTM-HF. The same applies when charging batteries with special charging curves, such as valve-regulated (maintenance-free) batteries.
Wa chargers are characterised by the charging current of the charger being reciprocally proportional to the counter voltage of the battery. The charger delivers high current at low battery voltages and low current at high battery voltages. To be precise, the charger delivers the rated current at 2.1 V/cell, 50% of rated current at 2.4 V/cell and finally 25% at 2.6 V/cell.
Wa chargers are not regulated. The Wa curve is created by correctly dimensioning the transformer and the choke coil. The charging process is affected by variations in mains voltage. In order to compensate for major deviations in mains voltage, the chargers can be switched between low and normal mains voltage.
Using thyristor regulation, the charging process can be actively controlled without being affected by variations in mains voltage.
The thyristors are controlled by a microprocessor, and by providing the charger with different charging programmes (charging curves), batteries with different characteristics can be charged.
The IU curve allows the charger to give full charging current, often I5 (the battery’s 5-hour current) up to 2.4 V/cell. This makes for shorter charging times than with a Wa charger, or in other words the same charging time but with one charger size smaller.
For 10 years, Micropower has delivered the TTMV charger for a number of different applications. The TTMV charger has been used both for charging valve-regulated batteries and a charger in AGV systems. A number of different charging curves have been developed in collaboration with battery suppliers.
The TTMV charger has been replaced by the MTM charger, which is a more modern variant with new functions such as a real-time clock, predefined charging curves, etc.