I use my seldom used 100A tractor battery for buffer. Instead of reminding myself every couple of months to keep it charged (I use it like three times a year),

I use my seldom used 100A tractor battery for buffer. Instead of reminding myself every couple of months to keep it charged (I use it like three times a year), its now on purpose. I have a guard to prevent the lead-acid battery from a deep decharge.