11:40 UTC very unstable oscillator frequency (howling beacon) due to low battery voltage

RX setup: SDR# and FUNcube Dongle Pro+
54 F0 E5 80 00 45 01 00 02 86 03 02 04 00 05 00 06 00
54 F0 E4 80 00 45 01 00 02 86 03 02 04 00 05 00 06 00
54 F0 E3 00 00 46 01 00 02 87 03 02 04 00 05 00 06 00
54 F0 E2 80 00 46 01 00 02 86 03 02 04 00 05 00 06 00
54 F0 E1 80 00 46 01 00 02 86 03 02 04 00 05 00 06 00

normal range is above 11 volts