Motorists urged to check 12V battery health as winter sets in
Low temperatures and unprecedented demands on 12V vehicle battery systems has seen Clarios, the company behind the Varta brand, warn of the risks of failing to check battery health.
With increased demands on the battery, across both electric vehicles (EVs) and those with combustion engines, door lock-outs, starting difficulties and other problems often occur in winter when temperatures are low. Battery capacities are reduced in low temperatures, especially if the battery has already been damaged by high temperatures in summer.
The 12V battery remains by far the most common cause of a breakdown – and more so for electric vehicles. Germany’s ADAC has reported a greater proportion of EVs requiring assistance with the 12V system, than those of conventional combustion engines. According to ADAC’s 2022 figures, in 43.2 per cent of these cases the fault was caused by the failure of the 12V battery, while electric cars accounted for 55.6 per cent of defective 12V batteries.
AA Ireland has also previously reported that the majority of breakdown cases are due to battery difficultly. And with the cumulative number of EVs on Ireland’s roads at an all-time high, this is a trend that is most likely set to continue.
Andy Cook from Varta said: “Batteries must be looked after, a battery test-check is an essential part of preparing for all weathers, but only trained specialists can ensure the correct replacement battery for a vehicle. This ensures that essential performance and safety functions continue to operate correctly.”
Why do low voltage batteries in electric cars fail?
The 12V batteries in the first generation of electric cars have now reached the end of their service life, usually needing to be replaced after three to five years. With some models, the failure is due to the usage of the 12V battery in the electrical system of the car.
“In some EV’s systems, the charging strategy for the 12V battery has not yet been perfected,” said Clarios design engineering lead, Nadine Dehnert.
“This often leads to the 12V battery being deep-discharged, as more power is demanded than is available. If the battery is not recharged fully, for example because the vehicle is left without power for a longer period, or not sufficiently charged by the high-voltage battery during a drive cycle, this can ultimately lead to failure.
“Through better charging strategies for the 12V battery or by using larger battery types, vehicle manufacturers could minimise or even completely prevent the problem.”
System updates need a great deal of power
Regular software updates for EVs consume power, which is supplied by the 12V circuit. The high voltage battery is often powered up several times during the update, or the car is ‘woken up’ up again-and-again for other reasons. If this happens several times without the battery being recharged, it may not be possible to unlock or start.
Box: Top tips for EV drivers
- Park the car in a garage overnight, if possible. This avoids excessive load on the high voltage battery and is also good for the 12V battery.
- Pre-heat an electric car only while it is connected to the charging point, to maximise the driving range. In most cases, the heat is provided by the power outlet, which means less heating is needed during the journey. This reduces the load on the high voltage battery.
- Check if your vehicle’s 12V battery still draws heat during charging. If so, if the battery is discharged before the high voltage battery is fully charged, it may not be possible to remove the charging plug, as this is controlled by a circuit powered by the 12V battery.