Side-by-Side Comparison
Electrical & Ignition Standards
Automotive Relays & ISO Pinouts vs. Car Battery BCI Group Sizes
Comparing 2 standards across 16 specifications. 16 key differences identified.
Comparing:
Automotive Relays & ISO Pinouts
Car Battery BCI Group Sizes
Automotive electromechanical relays switch high-current vehicle loads (cooling fans, fuel pumps, headlights, starter solenoids) using low-current control signals, standardized under ISO 7588 into Mini (1-inch cube) and Micro form factors with standard DIN 72552 terminal numbering (30, 85, 86, 87, 87a).
Lead-acid and AGM 12V starter batteries are standardized by the Battery Council International (BCI) and EN/DIN into group sizes defining physical box dimensions (length × width × height), terminal post orientation (top post vs side post vs recessed European DIN), hold-down ledge profiles, and Cold Cranking Amperage (CCA).
Specification Comparison Table
16 Parameters| Parameter / Spec | ||
|---|---|---|
|
Governing Standards
|
ISO 7588 / DIN 72552 / SAE J2544 | BCI Standards / EN 50342 / DIN 72311 / JIS D 5301 |
|
Form Factor Tiers
|
ISO Mini Relay (~28×28×25 mm) / ISO Micro Relay (~22×15×25 mm) / Maxi Relay | — |
|
Contact Switching Ratings
|
Mini: 30A to 50A at 14V DC | Micro: 20A to 35A at 14V DC | — |
|
Nominal Coil Voltages
|
12V DC (automotive passenger cars) / 24V DC (heavy commercial trucks) | — |
|
Terminal 30 (DIN 72552)
|
Common High-Current Power Input (Fused Battery B+ feed) | — |
|
Terminal 85 (DIN 72552)
|
Relay Coil Ground / Trigger Return (connected to ECU or ground switch) | — |
|
Terminal 86 (DIN 72552)
|
Relay Coil Power (+12V ignition switch or control trigger) | — |
|
Terminal 87 (DIN 72552)
|
Normally Open (NO) Output — Energized when coil is activated | — |
|
Terminal 87a (DIN 72552)
|
Normally Closed (NC) Output — Energized when coil is unpowered (5-pin SPDT only) | — |
|
Primary Dimension Landmarks
|
— | Physical Length × Width × Total Height (including terminals) in mm and inches |
|
Group 24
|
— | 260 × 173 × 225 mm (10.25 × 6.81 × 8.88") | Standard Japanese/American SUV & Truck |
|
Group 35
|
— | 230 × 175 × 225 mm (9.06 × 6.88 × 8.88") | Honda, Toyota, Nissan, Subaru sedans |
|
Group 48 / H6 (DIN L3)
|
— | 278 × 175 × 190 mm (10.94 × 6.88 × 7.50") | Universal European/US modern vehicle standard |
|
Group 49 / H8 (DIN L5)
|
— | 353 × 175 × 190 mm (13.90 × 6.88 × 7.50") | Large luxury sedans, BMW, Audi, Mercedes, Porsche |
|
Group 51R
|
— | 238 × 129 × 223 mm (9.38 × 5.06 × 8.81") | Compact Honda Civic, Fit, S2000 (R = Reversed Polarity) |
|
Group 94R / H7 (DIN L4)
|
— | 315 × 175 × 190 mm (12.40 × 6.88 × 7.50") | Heavy-duty European crossovers & US pickups |