Skip's Corner

Annunciator light functionality - NiCads

The Question –

Working on King Air 300 FA-85 with RG380E/44 installed. Have minor issue with Batt charge annunciator and can not locate wiring changes made when ACFT went from NiCad to Lead acid. If you could assist or point me in direction who could please do. Thanks for your time.

The Answer –

The CONCORDE King Air STC has the option of taking one of the battery charging cable shunt sensing lead off if the charge light is a nuisance to the operator.

But, it is a great system and the light comes on as long as at least 7 to 10 amps are charging the battery. Normally, with a healthy battery the light goes out before takeoff. IF THE CHARGING SYSTEM IS SET PER THE BEECH MM AT 28 TO 28.5 DCV.

Most of the NiCad's are 20 cell and the charging system is set upwards of 29DCV which is too high for our 24V batteries and the charge light stays on for a long time .

The reason we like to leave the charge light system functional is that it is a CURRENT SENSING SYSTEM And if the light comes on during flight, the pilot merely disconnects the battery that is just showing signs of an internal short , but fully charged and if later the generating system fails, the charged battery can be put back on line to support the load requirements.