Choosing the right battery capacity to support key-off and anti-idle loads

Avoid premature battery failure by choosing the proper battery technology to match the frequency and duration of key-off or anti-idle loads.

Every cycle, the battery will only recover to “very near” its original capacity if adequately charged. Even if properly charged, a lead-acid battery incrementally loses some of its original capacity with each successive discharge event. A standard starting battery can only be regularly discharged to <3% before it experiences negative consequences. A high-capacity (high Reserve Capacity - RC, or Amp hour- Ah) heavy-duty battery with a deep-cycle design can only regularly use a maximum of 30% of its rated capacity before causing incremental and permanent damage. Discharging a starting battery to 50% or a lower depth of discharge will dramatically reduce battery life.

The battery you choose needs to have adequate specifications to support the job it's being asked to do. Your maintenance supervisors and operators should be trained in best maintenance practices to protect this investment.

Choose battery technology that includes: 

  • Countermeasures against acid stratification by introducing acid mixing or immobilization technology. 
  • Deep and micro-cycle capability through enhanced active material ratios, densities and alloys (less of a starting battery and more of a cycling battery). 
  • Fibre dividers reinforce active material against shedding caused by acid stratification and vibration. 
  • Enhanced negative plate performance through increased carbon and/or other additives. 
  • Element bonding that protects against positive grid growth and vibration. 
  • Anchor bonding that protects against shock and vibration. 
  • Higher lead content using thicker or more plates may be sufficient to secure the increased positive and negative plate active material for increased capacity (high reserve capacity or amp hour) and cycle life while maintaining enough surface area to produce adequate cold cranking performance (CCA).

A few words about acid mixing and acid immobilization...

Acid mixing technology uses components that mix the acid to equalize the acid’s specific gravity evenly throughout the battery’s cells. Acid immobilization technology uses absorbent glass-mat material to suspend acid to slow stratification in the battery’s cell (“AGM” batteries). While the same electrochemical reactions take place, the negative consequences of acid stratification are delayed in acid mixing and AGM batteries because acid mixing technology defeats acid stratification and acid immobilization technology slows (but does not entirely stop) the stratifying effect of gravity on battery acid.