TC reported battery charge loss. SM (AMK) checked and confirmed no fault found. ERS-15 ~~~~~ 3610 found no FC on battery charge loss on all 6 cars. Checked all 6 cars line voltage, APS output, BATK, AC voltage, DC voltage, Battery voltage - All OK. Physically checked all battery temp. stickers & use multimeter to check battery fuse - All OK & in position. Battery Voltage (VDC) : Bank No.1     Bank No.2    Total 3609                  :  46.80         51.80       98.60 1609                  :  46.60         5174        98.34 2609                  :  46.71         5180        98.51 2610                  :  46.70         50.95       97.65 1610                  :  46.62         51.82       98.44 3610                  :  46.10         51.70       97.80  Chan SW/Hanafi. 21/12/2020.  3610 Line 53 found with 16.15v when train was AUX O . Further checked found #2610 wires 53 & 5301 with 16.15v.  Goh at/Chan GF. 21/12/2020.  EMU 609/610 joint inspection with RSW staff. After removed wire 6621 at APS control box from diode base plate joined to 6606 & reconnected back, fault cleared. No 16.15v was present at wire 5301 to GND.  Goh AT/Chan GF. 22/12/2020.