Words of Wisdom:
Over many years of capacity testing hundreds and hundreds of batteries, flooded, GEL and AGM I have yet to see a lead acid battery that could delivers its full storage potential at anything less than 0.75%1)
in tail current at absorption voltage. MaineSail2)
Battery murder (or Batterycide) is the murder of batteries by newbs (new users), poor quality chargers, etc. The term is commonly used by SternWake: “my goal here is to prevent batterycide.”3)
It is so common for new RVers to wreck their first set of house batteries that some recommend using cheap wally world batteries as sacrificial lambs to the learning process.4) As the RVers learns more and gets charging set up correctly they would invest in better quality batteries and have them last several years.
murdering flooded lead-acid
Flooded lead-acid (FLA) batteries are the most resillient to mistreatment but they too can be killed.
AGM have benefits but are easier to murder.
the lead-acid list above8)
Low current charging. Cheap AGM require C/5
current minimum in Bulk, and expensive ones require C/3.
overvoltage. 13.8v is a safe upper limit
without BMS and will charge the bank completely. Some experienced folk use slightly higher voltages for faster charging but it must be terminated quickly as the bank approaches 100% state of charge. Exception: Lithium banks with BMS typically overcharge intentionally to balance cells. The overcharge is consumed by resistors and does not actually go into the cell.
long periods of 100% state of charge; cease all charging at 100% and only charge that high if you know some loads will be applied immediately. Lithium chemistries do not care about partial state of charge so use that to your advantage.
exposure to high heat
attempting to charge at below freezing
poor quality BMS
high [dis]charge rates without BMS