Electrical Precautions

  • 2023-05-01: Updated HV battery storage temperature guidance.

General

Avoid getting grease on electrical components and connectors. Grease collects dirt, which can cause electrical tracking (short-circuits) or high resistance.

Handle printed circuit boards at an electrostatic discharge (ESD) work station only. Hold printed circuit boards by the edges only.

Voltages

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The vehicle has low voltage (12V) and high voltage (400V) circuits. The High Voltage (HV) system can be energized any time the 12V battery and first responder loop are connected. To fully disconnect the HV system, refer to Service Manual procedure 17010000, Vehicle HV Disablement Procedure.
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Only technicians who have been trained in High Voltage Awareness and have completed all required certification courses (if applicable) are permitted to perform this procedure. Proper personal protective equipment (PPE) and insulating HV gloves with a minimum rating of class 0 (1000V) must be worn any time a high voltage cable is handled. Refer to Tech Note TN-15-92-003, "High Voltage Awareness Care Points" for additional safety information.
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Make sure that multimeters and leads are capable of handling at least 500V before performing a procedure that involves high voltage.
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Never disconnect or cut an orange high voltage power cable or high voltage component unless the HV system has been disabled.
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After disabling the vehicle, power is maintained for 30 seconds in the SRS system and 1 minute in the high voltage electrical system.
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Never cut into the HV battery enclosure.

HV battery

The HV battery stores all of the energy for the motor and vehicle electrical systems. The battery can sense a variety of conditions that could potentially damage the vehicle or pose a safety risk. Its primary response in these circumstances is to disconnect the high voltage from the rest of the vehicle.

When the battery is not in a vehicle, high voltage is not accessible without removing the enclosure cover.

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Always remove the HV Battery before performing any procedure that might require using a drill near the HV Battery, especially drilling downward from inside the vehicle.
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A HV battery poses a significant high voltage and electrocution risk if the outer enclosure or safety circuits have been compromised or have been significantly damaged.
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If the battery or vehicle displays signs of escaping gases, smoke, flames, excessive heat, sparks or arcing, contact the local emergency department and refer to the Model S First Responder Guide, available at http://www.teslamotors.com/firstresponders and/or the Model S Lithium-Ion Battery Emergency Response Guide, TN-13-16-007. Gases or smoke exiting a lithium-ion HV battery are likely flammable and could ignite at any time.

12V battery

The 12V battery used in Model S is an AGM (Absorbed Glass Matt) type similar to the lead acid batteries used in some internal combustion engine vehicles. The acid electrolyte is absorbed into the glass mats so it is non-spillable.

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Lead acid batteries contain an electrolyte with dilute sulfuric acid, which can cause severe chemical burns if it comes in contact with skin.
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Lead acid batteries can emit hydrogen and oxygen, which can result in an explosion under certain conditions. Only charge the 12V battery in a well-ventilated area that is free from sparks or open flame.
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Keep the 12V battery upright at all times. The 12V battery is vented (not sealed), allowing the sulfuric acid to spill out if the battery is not kept upright.
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Use only battery chargers specified by Tesla. Charging the battery outside of the recommended specification can cause the battery to overheat and increase the possibility that acid and hydrogen gas will be released, possibly causing personal injury, damage to the vehicle, fire, or an explosion.
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Batteries can be a source of high electrical current and can cause an electrical shock in certain situations, such as a short circuit.
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To avoid personal injury, use proper lifting techniques when handling the 12V battery.
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CAUTION
The HV battery in Model X will support a damaged/over discharged 12V battery whether or not the car is being driven. However, upon detection of 12V battery degradation, the vehicle provides alerts indicating that the 12V battery needs replacement. If these alerts are ignored for a considerable period of time, the HV battery can become discharged to the point of no longer supporting the 12V battery (and the vehicle will have to be jump-started), or the 12V battery may become overheated due to nearly continuous charging.
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CAUTION
Over discharging a battery can cause permanent damage to the battery and increase the likelihood of overheating during charging. If a vehicle has an over discharged or "dead" 12V battery, always replace the 12V battery. Even if an over discharged battery is charged again successfully, the damage incurred is likely to cause future reliability problems.
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CAUTION
Prevent unnecessary 12V battery replacement. If a vehicle is unable to support the 12V battery or has a low HV State of Charge (SOC) and is unable to be recharged, disconnect 12V power (refer to procedure). Keeping the 12V battery connected on these vehicles might result in damaging the 12V battery through over-discharge.
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Note
An overheated 12V battery can begin to leak acid from the vent hose, begin to smell of “rotten eggs”, and may become swollen.

Electrical connectors and harnesses

  • Never pull on a wiring harness to disconnect an electrical connector.
  • Never use tools to force connectors apart.
  • Ensure that disconnected connectors and sensors are protected from oil, coolant, water, or other contaminants.
  • Ensure that electrical items are dry and free of oil or grease before disconnecting and connecting test equipment.
  • After reconnecting an electrical connector, lightly pull on it to ensure that it is secured.
  • When replacing a component, keep oily hands away from electrical connection areas.
  • Ensure that any protection (cover, insulation, etc.) is replaced if disturbed.

Grease for electrical connectors

Some underhood and underbody connectors might be protected against corrosion by the application of a special grease during vehicle assembly. Apply the appropriate grease when repairing or replacing these connectors. Do not use other greases. Incorrect greases can migrate into relays, switches, etc. contaminating the contacts and leading to intermittent operation or failure.

Do not apply grease to any connectors that do not have grease applied from the factory.

First aid measures

Seek immediate medical assistance if an electrical shock or electrocution has occurred or is suspected.

Under normal conditions, technicians are not exposed to the contents of the HV battery cells. If materials from a ruptured or otherwise damaged battery contact skin, flush immediately with water and wash the affected area with soap and water. Avoid inhaling any vented gases. If a chemical burn occurs or if irritation persists, seek medical assistance. For eye contact, flush with significant amounts of water for 15 minutes and see a physician immediately.

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An HV battery poses a significant high voltage and electrocution risk if the outer enclosure or safety circuits have been compromised or have been significantly damaged.
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Avoid contact with gases escaping from a damaged battery. Vented gases might irritate the eyes, skin, and throat. Vent gas temperatures can exceed 600 ºC (1,110 ºF). Contact with hot gases can cause burns.

HV battery storage precautions

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Warning
  • Do not store HV batteries below -20 ºC (-4 ºF).
  • Do not store HV batteries for over 10 days above 40 ºC (104 ºF).
  • Do not charge or discharge an HV battery below 0 ºC (32 ºF).
  • Do not store HV batteries for over 30 days at full state of charge (SOC) or completely discharged.
  • Do not weld near HV batteries.

Install the following covers on the HV battery rapid mate connectors before storing the HV battery:

  • Coolant rapid mate cover (TPN 1005706-00-C) on the coolant connector.
  • HV battery rapid mate safety cover (TPN 1016196-00-A) on the high voltage connector.
  • LV rapid mate safety cover (TPN 1016197-00-A) on the low voltage connector.
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Note
If either rapid mate safety cover is not available, cover the connector with 3M 2480S masking tape or 3M 471 vinyl tape.

HV batteries should be stored in a dry area, in approved packaging or on non-conductive surfaces. To reduce the risk of accidental shorting, ensure that there is no loose metal or other conductive materials near stored batteries.

HV batteries should not be stored longer than 9 months since battery service life likely will be affected. If longer storage is anticipated, contact Tesla for instructions.

HV battery disposal procedures

The lithium-ion cells contained in the battery do not contain heavy metals such as lead, cadmium, or mercury.

HV Batteries should be disposed of or recycled in accordance with local, state, and federal regulations. Regulations regarding disposal of batteries vary by jurisdiction. In the United States, batteries are classified as Universal Waste, and in addition, many individual states have specific regulations regarding disposal of batteries.

HV batteries contain recyclable materials. Tesla strongly encourages recycling. Tesla recommends that that all HV batteries be taken to a Tesla Service Center so that the batteries can be evaluated, and, if appropriate, be recycled in a safe and efficient manner.

If disposing of a battery without returning it to Tesla, consult with local, state and /or federal authorities on the appropriate methods for disposal and recycling.