I was fortunate to be involved in a conversation with a senior manager at the company where I work today. I am told that the company I work for is putting pressure on the airline industry to update the 30+ year old technology used by the pinger system and to aim to have FDR's use a transponder system, so they will not transmit until interrogated. This will mean that the battery life will increase, to up to 5 years.
We can do with support from those in the aviation industry to take this further, I am sure.