Lock-down advice for Hybrid cars

Posted on May 1st, 2020 by Rob Marshall

Lock-down advice for Hybrid cars


While batteries are, probably, the most likely item affected by short-term storage, most of our advice so far has focussed on the 12-volt lead-acid item. However, members have contacted us for advice about how to maintain the high-voltage battery that is fitted typically to electric and hybrid cars.


12v battery advice is still relevant

Most owners are surprised that their hybrid and electric cars still possess a 12-volt battery. Apart from powering the car’s ancillary circuits, the 12-volt battery activates the high-voltage system that powers the road wheels. Should it become discharged, the 300+ volts circuit will not be triggered and the car cannot be driven, even if the high-voltage battery is in good order. In conventional parlance, the car will not ‘start’. Therefore, GEM’s advice on maintaining 12-volt batteries is just as relevant to hybrids and EVs as it is to cars with combustion engines alone. < https://blog.motoringassist.com/news/how-to-look-after-your-car-battery-during-lockdown/>


A major difference, however, is that the 12-volt battery may not be charged by a conventional alternator but by the high voltage circuit. In these cases, the simplest way to keep the 12-volt battery topped-up is to activate the high voltage system, by depressing the ‘Start’ button (in the case of keyless models) and note that a ‘ready’ (or similar) message/lamp appears on the fascia. In effect, this means that the car is ready to be driven and so it must not be left unattended. Lexus, for example, recommends you have the car activated in its ‘ready’ state for around an hour every few weeks, so take a good book with you!


However, on certain hybrids, this may mean that the internal combustion engine will start in order to charge the high voltage system. Therefore, ensure the car is out of the garage, where lethal carbon monoxide gas can build-up.

It is also worth noting that engines prefer not to be run occasionally, when not driven – we shall explain more in our next blog. Therefore, our best advice to keep a 12-volt battery fully charged is not to start the car but to use an intelligent mains-powered Smart Charger instead.