Roguebooks,
I have pretty much the same system you have. My Ollie is a year older, but the Lifelines are still going strong (13.8 V under solar float). I have not had any major short or electrical malfunction though. It has been stored outside since we brought her home and the sun has done the maintenance. I agree with Back of Beyond that the simple approach may give you the best option if you find that your Lifelines are done. As you can imagine, I am watching this closely and appreciate your sharing this. Like you, We hope to use our LE1 for at least another 5-6 years.
Best of luck,