2019 Subaru Forester — Battery Size & Group

Quick answer

• BCI group size: Group 35 (top‑post)
• Cold cranking amps (CCA): OEM ~550 CCA; recommended replacement 600–650+ CCA
• Reserve capacity (RC): ~95–100 minutes (typical for quality Group 35)
• AGM vs flooded: Came with standard flooded; AGM/EFB strongly recommended for vehicles with Auto Start‑Stop or in harsh climates
• Terminal layout: Top SAE posts; positive on right when posts are closest (BCI orientation “A”)
• Physical dimensions (Group 35): approx. 9.1" L × 6.9" W × 8.9" H (230 × 175 × 225 mm)
• Dual‑battery (diesel): Not applicable — 2019 Forester was gasoline only

Replacement battery options

These are common, direct‑fit Group 35 choices. Always verify fitment and specs for your trim and climate.

• Interstate MT‑35 (flooded) — solid value around 640 CCA, ~100 RC
• Interstate MTX‑35 (AGM) — AGM upgrade, typically ~650 CCA
• DieHard Gold Group 35 (flooded) — robust everyday choice, around 640 CCA
• DieHard Platinum AGM Group 35 — AGM upgrade, ~650–680 CCA range
• Optima RedTop 35 — spiral‑cell AGM, high cranking performance (often ~720 CCA)
• Odyssey 35‑PC1400 (AGM) — premium AGM with strong reserve and cycle life
• ACDelco Gold Group 35 (AGM or flooded variants) — OE‑style fit and performance

Note: Listing names only where widely standardized; verify exact store SKU/part code at purchase.

AGM vs flooded — which does this vehicle need?

• Factory equipment: Most 2019 Subaru Foresters were supplied with a standard flooded Group 35 battery.
• Start‑Stop consideration: If your Forester is equipped with Auto Start‑Stop, an AGM (or at minimum an EFB) is strongly recommended. Start‑Stop cycles and short‑trip driving are hard on conventional flooded batteries.
• Why choose AGM:
  • Better tolerance for repeated discharge/charge cycles
  • Lower self‑discharge and improved performance in cold weather
  • Spill‑proof design and typically longer warranty
• Electrical system compatibility: The Forester’s charging system does not require coding when switching between flooded and AGM in Group 35. Just match the group size, terminal layout, and meet or exceed OEM CCA.

Post-installation relearn / reset procedure

After reconnecting the battery (negative last), perform these steps to restore normal operation:

1. Idle learn:
   • Turn off HVAC, lights, and accessories.
   • Start engine and let it idle in Park for ~10 minutes until warm and stable.
   • Turn A/C on and idle an additional ~10 minutes (helps the ECU adapt to load).
2. Steering angle/VDC lights:
   • With engine running, slowly turn the steering wheel full left, then full right, then center. Any VDC/traction lights should clear after driving a short distance.
3. Power window auto‑up/down:
   • For each window: key ON, close the window fully, then hold the switch UP for 3–5 seconds to re‑initialize auto function.
4. Radio/clock and presets:
   • Re‑set time, radio presets, and any user preferences.
5. EyeSight/driver‑assist messages:
   • Temporary warnings after a power loss are common. They typically clear after a short, straight drive with clean windshield/glass. If not, check for stored DTCs.

Tips:

• Use a memory saver to avoid resets where possible.
• Ensure terminal clamps are clean and snug; do not overtighten. Protect with dielectric grease.

Signs of a failing battery

• Slow or hesitant cranking, especially after overnight cold soak
• Flickering or dim interior/exterior lights at idle
• Auto Start‑Stop disabled or frequent “battery charge low” messages
• Multiple warning lights after start that clear as you drive (voltage sag)
• Sulfur/rotten‑egg smell, bulging case, or excessive corrosion on terminals
• Repeated jump‑starts or the need to charge after normal use

Common battery issues for this generation

• High accessory load and short‑trip driving: The Forester’s electronics and frequent short trips can leave the battery undercharged, accelerating sulfation.
• Start‑Stop stress: Conventional flooded batteries wear quickly under Start‑Stop cycling. Upgrading to AGM/EFB significantly improves durability.
• Parasitic draw complaints: Some owners report intermittent draws (modules staying awake). Keeping software updated and ruling out aftermarket accessories (dash cams, remote starters) helps.
• Ground/connection corrosion: Corroded terminals or body grounds cause charging and starting complaints. Clean and protect connections during replacement.
• Low‑temperature performance: The small physical footprint of Group 35 means selecting a battery with higher CCA is beneficial in cold climates (aim for 650+ CCA if possible).

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