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How to Read Battery Specifications

Key Specifications

Voltage

  • 12V — Standard for all passenger and commercial vehicle starting batteries
  • 24V systems use two 12V batteries in series

Capacity (Ah — Ampere-Hour)

  • Typically rated at C20 (20-hour discharge rate)
  • Example: 65Ah means the battery can deliver 3.25A for 20 hours
  • Higher Ah = longer runtime, more energy storage

CCA (Cold Cranking Amps)

  • Current delivered at -18degC for 30 seconds, maintaining >7.2V
  • Most important spec for cold-climate starting
  • Different standards use different test methods:
Standard Test Method Compared to SAE
SAE -18degC, 30 sec Reference
EN -18degC, 10 sec ~1.1x SAE
DIN -18degC, 30 sec ~0.9x SAE
JIS -15degC, varies ~0.7-0.8x SAE

CCA Is Not Universal

A battery rated 500 CCA (SAE) may be rated ~550 EN or ~450 DIN. Always check which standard the CCA rating refers to.

RC (Reserve Capacity)

  • Minutes at 25A discharge, 27degC, before dropping below 10.5V
  • Important for vehicles with heavy electrical loads

Dimensions

  • Length x Width x Height (in mm)
  • Total height may differ from case height (includes terminals)
  • Must match vehicle battery tray

Terminal Type & Polarity

  • Must match vehicle cable configuration
  • Wrong polarity can damage vehicle electronics

Understanding Battery Labels

Example battery label:

12V  65Ah  C20
CCA 550A (SAE)
260 x 173 x 225 mm
L- R+  [0]

Reads as:
- 12 volt system
- 65 amp-hours (C20 rate)
- 550 cold cranking amps (SAE standard)
- Case dimensions in mm
- Left negative, right positive, polarity type 0