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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

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 Costco golf cart 6v batteries or wally world batteries as sacrificial lambs to the learning process.4) As the RVers learns more they would invest in better quality batteries.

murdering flooded lead-acid

Flooded lead-acid (FLA) batteries are the most resillient to mistreatment but they too can be killed.

murdering AGM

AGM have benefits but are easier to murder.

  • the lead-acid list above8)
  • overvoltage
    • Incorrect Absorption setpoints. AGM is commonly Absorped at ⇐ 14.4v while FLA is commonly Absorped higher (at 14.7v-14.8v). Check your manufacturer's recommendation and do not exceed it. Overvoltage causes irrepairable damage by outgassing, and AGM cannot be topped off again like FLA.
    • Equalization. Do not equalize AGM!9).
  • Low current charging. Cheap AGM require C/5 current minimum in Bulk, and expensive ones require C/3.

murdering lithium

  • 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
electrical/batterycide.txt · Last modified: 2020/10/11 19:48 (external edit)