Peugeot 308 12 V Battery and Jump Starting (2021-2025)

Hello and welcome. In this article we look at the 12 V battery on the Peugeot 308 III (2021-2025). We will cover battery safety, reaching the battery, jump starting, charging with a charger, and disconnecting and reconnecting it on petrol, Diesel, hybrid and rechargeable hybrid versions.

Quick Reference

Lead-acid starter batteries

Your 308's starter battery is a lead-acid battery. It contains harmful substances: sulphuric acid and lead. Never throw it away with household waste. Dispose of a used battery at a designated collection point, in line with regulations.

Before you work on the battery:

• Protect your eyes and face before handling the battery.
• Always work in a well ventilated area, away from naked flames and sources of sparks, to avoid any risk of explosion or fire.
• Wash your hands when you have finished.
• Never connect the negative jump lead to the metal part of the electronic control units or to the back of the headlamps. This can destroy the control units and/or the LED headlamps. Use the remote earth point provided for this purpose.
• Never try to charge a frozen battery, as it can explode. If the battery has frozen, have it checked by a PEUGEOT dealer or a qualified workshop. They will check that the internal components are not damaged and that the case has not cracked, because a cracked case could leak toxic and corrosive acid.
• On a car with an automatic gearbox, never try to start the engine by pushing the car.

Electric vehicles: if the accessory battery is flat, you can no longer start the motor or recharge the traction battery. Before you work on the accessory battery, select mode P, switch off the ignition, check that the instrument panel is off and make sure the car is not charging. Do not use the accessory battery to jump start another vehicle or to charge another vehicle's battery.

Symbols on the battery:

• No sparks or naked flames, no smoking.
• Always protect your eyes. Explosive gases can cause blindness and injury.
• Keep the battery out of the reach of children.
• The battery contains sulphuric acid, which can make you go blind or cause severe burns.
• For more information, refer to the handbook.
• Explosive gases can be present close to the battery.

For petrol/Diesel versions

This section explains how to start a petrol or Diesel 308 using another battery, and how to charge a flat battery.

Accessing the battery: the battery is under the bonnet.

1. Release the bonnet: pull the internal release lever, then the external safety catch.
2. Open up: raise the bonnet.

• (+) terminal: positive terminal with a quick-release terminal.
• (-) terminal: negative terminal. You cannot reach it, so a remote earth point is fitted near the battery.

Starting using another battery: if your battery is flat, you can start the engine with a backup battery (external or from another vehicle) and jump leads, or with a battery booster.

• Never start the engine by connecting a battery charger.
• Never use a 24 V or higher battery booster.
• Check first that the backup battery has a nominal voltage of 12 V and a capacity at least equal to that of your flat battery.
• Make sure the two vehicles are not touching each other.
• Switch off all electrical equipment on both vehicles (audio system, wipers, lighting, etc.).
• Keep the jump leads well away from the engine's moving parts (fan, belt, etc.).
• Do not disconnect the (+) terminal while the engine is running.

1. Uncover the terminal: lift the plastic cover on the (+) terminal, if your car has one.
2. Red cable: connect it to the (+) terminal of flat battery A (at the metal elbow), then to the (+) terminal of backup battery B or of the booster.
3. Green or black cable, first end: connect it to the (-) terminal of backup battery B or of the booster (or to an earth point on the assisting vehicle).
4. Green or black cable, other end: connect it to earth point C.
5. Assisting vehicle: start its engine and leave it running for a few minutes.
6. Your car: operate the starter and let the engine run. If the engine does not start straight away, switch off the ignition and wait a few moments before trying again.
7. Idle: wait for the engine to return to idle.
8. Disconnect: remove the jump leads in reverse order.
9. Cover the terminal: refit the plastic cover to the (+) terminal, if your car has one.
10. Recharge: let the engine run for at least 30 minutes with the car stationary, so the battery reaches an adequate state of charge.

If you drive off straight away before the battery has enough charge, some functions, such as Stop & Start, may be affected.

Charging the battery using a battery charger: keeping the battery properly charged gives it the best service life. You may need to charge it if you mainly make short journeys, or if the car will be off the road for several weeks. Consult a PEUGEOT dealer or a qualified workshop.

• To charge the battery yourself, use only a charger compatible with lead-acid batteries with a nominal voltage of 12 V.
• Follow the charger manufacturer's instructions.
• Never reverse the polarities.
• You do not need to disconnect the battery.
• If your car has the 12 V charger label shown in the handbook, use only a 12 V charger, to avoid irreversible damage to the electrical components.

1. Ignition: switch the ignition off.
2. Electrical consumers: switch off the audio system, lighting, wipers, etc.
3. Charger off: switch off charger B before connecting the cables to the battery, to avoid dangerous sparks.
4. Check the cables: make sure the charger cables are in good condition.
5. Uncover the terminal: lift the plastic cover on the (+) terminal, if your car has one.
6. Red cable: connect the positive (+) red cable of charger B to the (+) terminal of battery A.
7. Black cable: connect the negative (-) black cable of charger B to earth point C on the car.
8. Finish: when charging is complete, switch off charger B before disconnecting the cables from battery A.

Disconnecting/reconnecting the battery: if the car will be unused for an extended period, disconnecting the battery helps keep enough charge to start the engine. Before you disconnect it:

1. Openings: close all doors, the boot, the windows and the roof.
2. Electrical devices: switch off the audio system, wipers, lamps, etc.
3. Wait: switch off the ignition and wait for 4 minutes.

Once you have reached the battery, you only need to disconnect the (+) terminal, which has a quick-release clamp.

Disconnecting the (+) terminal:

1. Cover: depending on equipment, lift the plastic cover on the (+) terminal.
2. Release: raise lever A fully to release clamp B.
3. Remove: lift clamp B off.

Reconnecting the (+) terminal:

1. Lever up: raise lever A fully.
2. Refit: place open clamp B on the (+) terminal.
3. Push down: push clamp B fully down.
4. Lock: lower lever A to lock clamp B.
5. Cover: depending on equipment, lower the plastic cover on the (+) terminal.

Do not force the lever. If the clamp is not positioned correctly, it will not lock, so start the procedure again. Stop & Start may not work during the trip after the first engine start. It will only be available again after the car has been left still for a continuous period, which depends on the outside temperature and the battery's state of charge (up to about 8 hours).

For hybrid versions

This section covers starting a hybrid 308 using another battery, and charging a flat 12 V or 48 V battery.

Accessing the battery: the battery is under the bonnet.

1. Release the bonnet: pull the internal release lever, then the external safety catch.
2. Open up: raise the bonnet.

• (+) terminal: positive terminal with a quick-release terminal.
• (-) terminal: negative terminal. You cannot reach it, so a remote earth point is fitted near the battery.

Starting using another battery: the hybrid system starts the car, but it needs a 12 V supply, and there are several reasons why the car may not start. If the 12 V battery is flat, you can provide the 12 V supply with a backup battery (external or from another vehicle) and jump leads, with a battery booster or with a battery charger.

• Never use a 24 V or higher battery booster.
• Check first that the backup battery has a nominal voltage of 12 V and a capacity at least equal to that of your flat battery.
• Make sure the two vehicles are not touching each other.
• Switch off all electrical equipment on both vehicles (audio system, wipers, lighting, etc.).
• Keep the jump leads well away from the engine's moving parts (fan, belt, etc.).
• Do not disconnect the (+) terminal while the engine is running.

1. Uncover the terminal: lift the plastic cover on the (+) terminal, if your car has one.
2. Red cable: connect it to the (+) terminal of flat battery A (at the metal elbow), then to the (+) terminal of backup battery B or of the booster.
3. Green or black cable, first end: connect it to the (-) terminal of backup battery B or of the booster (or to an earth point on the assisting vehicle).
4. Green or black cable, other end: connect it to earth point C.
5. Assisting vehicle: start its engine and leave it running for a few minutes.
6. Your car: operate the starter and let the engine run. If the engine does not start straight away, switch off the ignition and wait a few moments before trying again.
7. Idle: wait for the engine to return to idle.
8. Disconnect: remove the jump leads in reverse order.
9. Cover the terminal: refit the plastic cover to the (+) terminal, if your car has one.
10. Recharge: let the engine run for at least 20 minutes with the car stationary, in a ventilated area so exhaust gases do not build up, so the battery reaches an adequate state of charge.

If you drive off straight away before the battery has enough charge, some functions, such as e-Auto mode, may be affected.

Charging the 12 V battery using a battery charger: keeping the battery properly charged gives it the best service life. You may need to charge it, for example if the car will be off the road for several weeks. Consult a PEUGEOT dealer or a qualified workshop.

• The hybrid system is connected to the 12 V network through the DC/DC converter, so any work on it may affect how the whole system behaves.
• To charge the battery yourself, use only a charger compatible with lead-acid batteries with a nominal voltage of 12 V.
• Follow the charger manufacturer's instructions.
• Never reverse the polarities.
• You do not need to disconnect the battery.

1. Ignition: switch the ignition off.
2. Electrical consumers: switch off the audio system, lighting, wipers, etc.
3. Charger off: switch off charger B before connecting the cables to the battery, to avoid dangerous sparks.
4. Check the cables: make sure the charger cables are in good condition.
5. Uncover the terminal: lift the plastic cover on the (+) terminal, if your car has one.
6. Red cable: connect the positive (+) red cable of charger B to the (+) terminal of battery A.
7. Black cable: connect the negative (-) black cable of charger B to earth point C on the car.
8. Finish: when charging is complete, switch off charger B before disconnecting the cables from battery A.

Charging the 48 V battery using a 12 V battery charger: if the car fails to start, first follow the "Starting using another battery" procedure above. If that fails, especially after long storage, the 48 V battery may be discharged and need charging.

• Do not try to charge the hybrid system directly.
• The hybrid system is connected to the 12 V network through the DC/DC converter, so any work on it may affect how the whole system behaves.
• Only use a specific 12 V battery charger capable of maintaining 13.5 V with a high level of current 40-50 A (approx. 600 W).
• Use only a charger compatible with lead-acid batteries with a nominal voltage of 12 V.
• Never use a 24 V or higher battery booster.
• Follow the charger manufacturer's instructions.
• Never reverse the polarities.
• You do not need to disconnect the battery.

1. Ignition: switch the ignition off.
2. Electrical consumers: switch off the audio system, lighting, wipers, etc.
3. Charger off: switch off charger B before connecting the cables to the 12 V battery, to avoid dangerous sparks.
4. Check the cables: make sure the charger cables are in good condition.
5. Uncover the terminal: lift the plastic cover on the (+) terminal, if your car has one.
6. Red cable: connect the positive (+) red cable of charger B to the (+) terminal of battery A.
7. Black cable: connect the negative (-) black cable of charger B to earth point C on the car.
8. Wake the car: open the driver's door and turn the ignition on without pressing the brake pedal.
9. Let it charge: after 1 minute with a 12 V supply higher than 13.5 V, the hybrid system starts charging the 48 V battery automatically. The charger should supply about 30-50A. The system stops charging by itself once the 48 V battery reaches the right energy level, which takes between 30 to 40 minutes depending on the 12 V battery's state of charge.
10. Charger off: switch off charger B before disconnecting the cables from 12 V battery A.
11. Cover the terminal: refit the plastic cover to the (+) terminal, if your car has one.
12. Start: operate the starter and let the engine run.
13. Idle: wait for the engine to return to idle.
14. Recharge: let the engine run for at least 20 minutes with the car stationary, in a ventilated area so exhaust gases do not build up, so the 48 V battery reaches an adequate state of charge.

Disconnecting/reconnecting the battery: if the car will be unused for an extended period, disconnecting the battery helps keep enough charge to start the engine. Before you disconnect it:

1. Openings: close all doors, the boot, the windows and the roof.
2. Electrical devices: switch off the audio system, wipers, lamps, etc.
3. Wait: switch off the ignition and wait for 4 minutes.

Once you have reached the battery, you only need to disconnect the (+) terminal, which has a quick-release clamp.

Disconnecting the (+) terminal:

1. Cover: depending on equipment, lift the plastic cover on the (+) terminal.
2. Release: raise lever A fully to release clamp B.
3. Remove: lift clamp B off.

Reconnecting the (+) terminal:

1. Lever up: raise lever A fully.
2. Refit: place open clamp B on the (+) terminal.
3. Push down: push clamp B fully down.
4. Lock: lower lever A to lock clamp B.
5. Cover: depending on equipment, lower the plastic cover on the (+) terminal.

Do not force the lever. If the clamp is not positioned correctly, it will not lock, so start the procedure again.

For rechargeable hybrid versions

The rechargeable hybrid 308 has two accessory batteries: one at the front and one in the centre of the car. To replace either of them, contact a PEUGEOT dealer or a qualified workshop. Do not use these batteries to start or jump start another vehicle.

Front battery: it is under the bonnet.

1. Release the bonnet: pull the internal release lever, then the external safety catch.
2. Open up: raise the bonnet.

• (+) terminal: positive terminal with a quick-release terminal.
• (-) terminal: negative terminal. You cannot reach it, so a remote earth point is fitted near the battery.

Central battery: it is in the front armrest storage compartment.

1. Armrest: open the front armrest.
2. Floor: unclip the floor of the compartment.

• (+) terminal: protected by a red plastic cover and not accessible.
• (-) terminal: negative terminal with a black quick-release connector.

Charging the front battery using a battery charger: keeping the front battery properly charged gives it the best service life. You may need to charge it if you mainly make short journeys, or if the car will be off the road for several weeks. Consult a PEUGEOT dealer or a qualified workshop.

• To charge the front battery yourself, use only a charger compatible with lead-acid batteries with a nominal voltage of 12 V.
• Follow the charger manufacturer's instructions.
• Never reverse the polarities.
• You do not need to disconnect the battery.

1. Ignition: switch the ignition off.
2. Electrical consumers: switch off the audio system, lighting, wipers, etc.
3. Charger off: switch off charger B before connecting the cables to the battery, to avoid dangerous sparks.
4. Check the cables: make sure the charger cables are in good condition.
5. Uncover the terminal: lift the plastic cover on the (+) terminal, if your car has one.
6. Red cable: connect the positive (+) red cable of charger B to the (+) terminal on battery A.
7. Black cable: connect the negative (-) black cable of charger B to earth point C on the car.
8. Finish: when charging is complete, switch off charger B before disconnecting the cables from battery A.

Disconnecting/reconnecting the accessory batteries: use this procedure if the car will be immobilised for a long time (more than 1 month). Before you disconnect the batteries:

1. Driver's door: open the driver's door.
2. Other doors: close all the other doors.
3. Electrical consumers: switch off the audio system, wipers, lamps, etc.
4. Ignition: switch off the ignition and wait for the READY indicator lamp to go out.
5. Wait: wait for 4 minutes.

Never change the order of the disconnection and reconnection steps, as this risks irreversible damage.

Disconnection:

1. Central battery: disconnect the (-) terminal using the black quick-release connector.
2. Front battery, release: raise lever A of the red quick-release clamp fully to release clamp B.
3. Front battery, remove: lift clamp B off the (+) terminal.

Reconnection:

1. Front battery, lever up: raise lever A of the red quick-release clamp fully.
2. Front battery, refit: place open clamp B on the (+) terminal.
3. Front battery, push down: push clamp B fully down.
4. Front battery, lock: lower lever A to lock clamp B.
5. Central battery: connect the (-) terminal using the black quick-release connector.

Following reconnection

After reconnecting the battery, turn on the ignition and wait 1 minute before starting the engine, so the electronic systems can initialise. If minor problems remain after this, contact a PEUGEOT dealer or a qualified workshop.

Using the relevant section of the handbook, reinitialise this equipment:

• Electronic key.
• Sunroof.
• Electric windows.
• Date and time.
• Preset radio stations.

When you switch on the ignition after reconnecting, the message "Collision risk detection system fault" appears on the instrument panel. This is perfectly normal, and the message disappears while you drive.

Frequently Asked Questions

Can I push start my Peugeot 308 automatic with a flat battery?

No. The handbook says you must never try to start the engine by pushing the car if it has an automatic gearbox. Use a backup battery with jump leads or a battery booster instead.

How long should I run my Peugeot 308 after a jump start?

On petrol and Diesel versions, let the engine run for at least 30 minutes with the car stationary. On hybrid versions, let it run for at least 20 minutes with the car stationary, in a ventilated area.

Can I use my Peugeot 308 plug-in hybrid to jump start another car?

No. The handbook says you must not start or jump start another vehicle using the rechargeable hybrid's accessory batteries.

Why does my Peugeot 308 show "Collision risk detection system fault" after reconnecting the battery?

This message is perfectly normal after the battery has been reconnected. It disappears while you drive.

A flat battery is easy to deal with once you know the right connection order and the safety rules for your version of the 308. Keep this guide handy, and if you are unsure at any stage, contact a PEUGEOT dealer or a qualified workshop.

More Peugeot 308 Guides

If a warning lamp comes on after a battery problem, check our guides to Peugeot 308 red warning lights, Peugeot 308 orange warning lights and Peugeot 308 green and blue indicator lamps.

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For more on this model, visit our Peugeot 308 guides.

Cover adapted from a photograph by Rutger van der Maar: Wikimedia Commons, CC BY 2.0.