Excellent point about fresh lead
My daily commute is 10 miles (5 each way) so instead of hauling around an extra 130 pounds of batteries, I went with six 8v (less expensive as well). My SOC doesn't get below 50%, so I should get good battery life. I planned the number of batteries based on the information in the 'battery FAQ'. Time will tell if it works out.
If I had to go 15 or 20 miles a day, it would have been worth getting the extra two batteries so the SOC wouldn't get too low, and I wouldn't worry about an extra mile or two beyond 20 miles for errands.
From the 'battery FAQ' -
If a battery is discharged to 50% every day, it will last about twice as long as if it is cycled to 80% DOD. If cycled only 10% DOD, it will last about 5 times as long as one cycled to 50%. Obviously, there are some practical limitations on this - you don't usually want to have a 5 ton pile of batteries sitting there just to reduce the DOD. The most practical number to use is 50% DOD on a regular basis. This does NOT mean you cannot go to 80% once in a while. It's just that when designing a system when you have some idea of the loads,
you should figure on an average DOD of around 50% for the best storage vs cost factor. Also, there is an upper limit - a battery that is continually cycled 5% or less will usually not last as long as one cycled down 10%.