Last Saturday I activated Place Fell, G/LD-027, and started with 2 metres SSB, intending to go on to FM and then 5 and 7 megs. At first all went well,but my fifth contact, Mike GW0DSP, reported problems with my modulation being distorted and difficult to tune in. It seemed better when I reduced power so I signed with him and went on to call CQ. It was at this point that I noticed that the battery voltage had dropped to 10.0 on receive. Clearly there was something wrong with the battery, which had been charged up two days earlier, so I terminated the activation and descended.
Yesterday I tested the battery and it seemed alright with plenty of life in it; I charged it up fully and found it ran the rig perfectly well, even at 50 watts output. The battery is a Yuasa 12 volt 7 ampere hour gel cell. I have had it for about five years so I suppose it doesn’t owe me anything! The question is, does the first sign of a battery passing its use-by date consist of a voltage drop at low temperatures (it was just below freezing at the summit) or must I look elsewhere for the cause of the problem?