The DDP Boost Voltage Charger is designed specifically for fast charging nicad packs used for electric flight of capacities 1000mA and over. It can charge battery packs from 6 to 14 cells from a 12 volt car battery source. Normal fast chargers powered from a car battery will not satisfactorily handle any pack greater than 7 cells. In order to charge pack sizes above this, the DDP charger is equipped with a sophisticated 'switch mode' power supply which is able to boost the supply voltage when charging larger batteries. The variable voltage booster only comes into operation when it is needed. This limits the energy required from the car battery and keeps down heat losses. Delta Peak Detection for determining end of charge is now accepted as the most practical method. Traditional and simple Delta Peak circuits can behave erratically and are not always ideal for charging differing pack sizes. MAINLINK has developed a microprocessor controlled system (Digital Delta Peak Detection ) that overcomes these limitations. This way, the peak detection algorithm is automatically graded to suit the number of battery cells. By using this technology, battery heating is kept to a minimum and the shut-off point is detected accurately.
In keeping with MAINLINK policy, we have added as much protection to the system as possible. The charger will not operate if either the 12 volt car battery or the nicad pack is connected incorrectly. To prevent accidentally charging the battery twice, the nicad pack has to be disconnected and reconnected before the unit can be re-started. Top-up charges will only run for the necessary time which can be upwards of 30 seconds. The charge time for nicads does vary slightly. Six cell 1200mA packs taking just under half an hour. Seven cell and upwards take just over half an hour. Trials have shown these to be optimum times for battery longevity.
Reviewed: Jun/Jul '92 R/C Model World, Jun '93 RCM&E, Jun '93 BMFA Newsletter, Sep '93 Radio Modeller.