2020 Tesla Model Y — Battery Size & Group (BCI), CCA, Replacement & Reset Guide

Quick answer

• BCI group size: H5 (aka Group 47, DIN/LN2)
• Cold cranking amps (CCA): Target ≥450 CCA; many AGM H5 options are 550–680 CCA
• Reserve capacity (RC): Approximately 90–100 minutes typical for AGM H5
• AGM vs flooded: AGM required (sealed, maintenance‑free). Do not use flooded
• Terminal layout: Standard H5 top posts; positive on right when posts are closest. Tesla’s OEM uses threaded studs—ensure compatible terminals/adapters
• Physical dimensions (H5/L2): ~9.6 x 6.9 x 7.5 in (242 x 175 x 190 mm)
• Dual‑battery setup: Not applicable (single 12V auxiliary battery)

Note: 2020 Model Y ships with a 12V lead‑acid AGM battery. Some later 2021+ vehicles use a lithium 12V pack that is not the same physical form factor. This page covers the 12V AGM configuration.

Replacement battery options

These are popular, direct‑fit AGM choices in BCI Group 47/H5. Use Tesla‑specific terminal adapters or a battery with dual SAE/threaded posts to match the factory cables. Never substitute a flooded (wet) battery.

• Interstate AGM — Group 47/H5 (AGM)
• DieHard Platinum AGM — Group H5
• Odyssey Performance AGM — Group 47 (H5)
• ACDelco Gold (Professional) AGM — Group 47/H5

If your Model Y has already been converted by Tesla to the lithium 12V module, use only the Tesla‑specified lithium assembly for your VIN; H5 lead‑acid batteries will not fit or function in that configuration.

AGM vs flooded — which does this vehicle need?

The 2020 Model Y requires an AGM (Absorbed Glass Mat) sealed battery:

• Location and ventilation: The 12V battery sits in the front compartment. AGM is sealed, spill‑proof, and tolerant of mounting angle and vibration.
• Charge profile: Tesla’s DC‑DC charging strategy is tuned for sealed VRLA/AGM chemistries. Flooded batteries can vent acid and may not charge correctly, leading to short life.
• Accessory loads: Sentry Mode, overheat protection, telematics, and frequent wake/sleep cycles benefit from AGM’s lower self‑discharge and better deep‑cycle tolerance compared to flooded.

Post-installation relearn / reset procedure

After installing the new 12V AGM battery and reconnecting the HV loop per Tesla procedures, allow the car to complete its startup and calibrations:

1. Initial boot: Close doors and frunk. Reconnect 12V first, then HV loop as specified by Tesla. Do not press the brake for 3–5 minutes while systems initialize.
2. Wake cycle: Let the vehicle sit powered (screen on) for ~5–10 minutes. You may hear relays and HVAC actuators calibrate; this is normal.
3. Window indexing: For each window, hold the switch fully up for 5 seconds, then fully down for 5 seconds to re‑teach auto‑up/auto‑down if needed.
4. Liftgate calibration (if behavior seems off): Manually open to desired height, then press and hold the close button until a chime.
5. Clock/GPS: Time/date should auto‑sync via LTE/Wi‑Fi. If not, connect to Wi‑Fi and allow a few minutes.
6. Driver profiles and settings: Verify mirrors, steering, and seat memory; re‑enable Sentry Mode, Cabin Overheat Protection, and charge limits as desired.
7. Drive verification: Take a short drive; any transient 12V or steering assist messages should clear on their own. If warnings persist, recheck connections and grounds.

Signs of a failing battery

• On‑screen alerts such as “12V battery needs service” or “Electrical system power reduced”
• Intermittent no‑start (won’t shift out of Park) despite a charged high‑voltage pack
• Charge port or door actuators slow to respond; contactor clicking on wakeup
• Sentry Mode disabled unexpectedly or frequent system reboots
• Headlights/infotainment flicker when accessories switch on

Most OE 12V AGMs in early Model Y vehicles last 2–4 years depending on climate and feature usage (Sentry, overheat protection).

Common battery issues for this generation

• High cycling from software updates and telematics: Frequent wake/sleep cycles can deep‑cycle the 12V more than in ICE cars, shortening life.
• Accessory drain: Extended Sentry Mode or cabin overheat protection in hot climates increases cycling; consider reducing usage when parked for days.
• Cold‑weather behavior: In freezing temps, voltage sag can trigger temporary 12V warnings; a healthy AGM with ≥450 CCA mitigates this.
• Ground and connection integrity: Ensure the negative ground strap and terminal fasteners in the frunk are tight and corrosion‑free; poor connections mimic battery failure.
• Wrong replacement type: Flooded or undersized batteries don’t tolerate Tesla’s charge profile and fail early. Stick with AGM Group H5 (47/L2).
• Lithium retrofit confusion: The Tesla lithium 12V module introduced later is not a drop‑in for 2020s without the proper harness and firmware. Use the correct part for your VIN.

Specs recap for 2020 Model Y (AGM configuration):

• Group: H5 / 47 / L2
• CCA: Aim for ≥450 CCA (many quality AGMs in this group are 550–680 CCA)
• RC: ~90–100 minutes typical
• Dimensions: ~242 x 175 x 190 mm (9.6 x 6.9 x 7.5 in)
• Terminals: Positive on right; use Tesla‑compatible threaded posts/adapters

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