In recent years, car manufactures have fitted Automatic Stop/Start technology to vehicles in a bid to reduce fuel consumption and emissions.  This system will shut down the engine when the vehicle is at a complete stop and re-engage the engine when you either put your foot on the clutch in a manual vehicle or press the accelerator in an automatic.

Fuel efficient and eco-friendly features sound good, but does Stop/Start technology affect battery health?

How does Automatic Stop/Start work?

In modern vehicles the engine is controlled by the Electronic Control Unit (ECU). This uses a variety of sensors and systems to control most functions, from controlling ignition timing to tracking wheel speed and braking power. The Electronic Control Unit is also responsible for Auto Stop/Start, which will only be engaged if the ECU determines that the vehicle has met the following criteria…

• The engine is warm.
• The brakes are fully engaged.
• The battery’s charge level is above 70%.

The ECU will also consider other factors such as transmission status.

If all of the above criteria is met, the engine will temporarily shut down. During this time, the vehicles other functions like air conditioning, infotainment systems and heated seats will all be powered by the 12v battery without any support from the vehicle. During this time the ECU will monitor the battery and when the charge level drops below a set threshold, the vehicle will re-start.

The strain on a 12V battery

The largest strain the battery is during the vehicles start cycle. This is why batteries account for the  large majority  of most non-starting vehicles. When starting up the engine again after using Auto Stop/Start technology, the same strain is placed upon the battery as when initially starting up the vehicle. There are a few potential issues with this…

1, With the engine restarting and the battery being placed under an intense strain multiple times in one journey, the number of discharge and recharge cycles will be much higher compared to a vehicle without Auto Stop/Start technology. This will contribute to the battery’s normal ‘wear and tear’ and can reduce the life span of the battery.

2, There is a higher starting load. The battery isn’t the only part to feel the pressure from Auto Stop/Start, there is also more strain put on the starter. Because of this vehicle manufacturers fit more durable and powerful starter motors. This is great for the vehicle but it requires more power and support from the 12v battery.

How to ensure battery longevity when using a vehicle with Auto Stop/Start Technology

To keep your vehicle in its best shape and to avoid battery failure we recommend the following…

Keep the battery clean.

As mentioned above, the engine will only shut down if the Electronic Control Unit (ECU) allows it. If there is anything hampering the ECU’s information then Auto Stop/Start will not function correctly and could cause your battery to drain. In most vehicles there is a small sensor next to the negative battery cable, which relays information to the ECU. We recommend checking your battery often and cleaning off any dirt and debris which could affect this sensor.

Regular battery testing

Like every vehicle we strongly recommend getting your battery tested and maintained at every opportunity. Regular battery testing allows you keep your battery in good condition and avoid the battery dying when you are out on the road. To test modern vehicles, battery testers such as Midtronics CPX-900 are fitted with Conductance Profiling technology that can simulate a load being placed on the battery to see if the battery can support your vehicle in its current state.

Regular Usage

A good way to keep your vehicle in good condition and on the road is to use it regularly. Using your vehicle regularly for at least 15 minutes or more ensures the battery gets charged and remains in a good state of health.