Lock-down: should you start your engine?

Posted on May 4th, 2020 by Rob Marshall

Lock-down: should you start your engine?

Many people have asked us whether, or not, they should start their engines to charge batteries. If you do not own a Smart charger, or have easy access to mains electricity, starting your car may be the only option you have. Yet, not only do you have to replenish the charge that starting the engine has taken out of the battery but also most car charging systems do not restore the battery to its preferred 90-100% state of charge and, even if it did, it would take around five hours at the very least.


Therefore, starting the car and letting it idle on your drive is not necessarily the best thing for the battery. It may not be the best thing for your engine, either. Despite the huge advances made in motorcar engine development, starting the car from cold creates the most amount of wear. Not letting it warm-up can also be harmful.


One reason is that burning a litre of petrol produces the same quantity of water. This not only condenses within the exhaust system but also contaminates the engine oil. If your car is not driven subsequently, the oil and exhaust systems tend not to reach high enough temperatures so that the water can evaporate. The result is increased engine wear and corrosion; pictured are rusty stains from an exhaust system that has rusted internally. Incidentally, modern self-charging petrol Hybrids have engines that switch on-and-off frequently; it is no coincidence that one of the largest manufacturers of replacement exhaust systems in the UK reports that Toyota Prius systems are among its most popular products.


Therefore, running an engine without taking it for a drive can be more harmful and wasteful than leaving it for several weeks. However, much depends on how long lock-down lasts. As the weather has been very fair, cars should not be deteriorating too markedly, by not being used. A further consideration is balancing harm to other components. The battery has been mentioned at length previously but consider that it is worth moving the car every 7-10 days slightly to reduce the chance of flat-spots developing on the tyres. Air conditioning also suffers when not used and so, should you decide to start your car, activate the system, which helps to keep it lubricated internally and reduces the risk of failure.