It depends. When is Armageddon going to get here?
Awww! I am just spoofing you Patrick.
It is however (and you have probably heard this too) a lot like asking, "I have a 20 gal. tank of gas, how long will it last in my car?" What you want to know is "what is the shelf life of that gas?"
I don't know that I can answer your question to your satisfaction, but maybe I can at least help you to formulate your own.
A lot of it has to do with cycles and how deep the cycles go. In your case, if the batteries are just sitting there "self discharging" during times of no Sunlight, then the cycles are extremely low, possibly < 5%, and this will, in effect, promote more than advertised cycles which if stated at all, is stated in terms of "number of cycles at a __ depth of discharge" which could be, 20% or 50%, possibly as low as 80% depth of discharge.
Now!, when "Armageddon"
gets here and you start to use the batteries, obviously that < 5% depth of discharge between times of no Sunlight will change and this in effect will change the number of cycles available and the over all life expectancy of the batteries.
It would seem that, right about now we have the need for a calculator capable of ciphering a balance between, depth of discharge and number of cycles, and it could be very complicated or very easy "depending" on how exact of an answer one is expecting. Variables that could change the outcome would involve such things as chemical composition, impurities, temperature, humidity, and time from date of conception. Some might argue that the date, time, and location of conception could be an aspect of the ratio's within the computations (astrologists). We are afterall, trying to foretell a future event. Give me a little time and I'll see what I can find. Later.