If you own a gas powered car, and it has been parked in the garage for days, maybe several weeks, and the main concern so far has been: what is the state of the battery? Okay, in case I take the boosters or borrow them (the cables that connect the batteries from one vehicle to another). This is the situation so far with coronavirus quarantine, when it comes to internal combustion engine cars, the petrol or diesel ones, but what if we had instead made the “leap” forward by purchasing an electric car?
Here the discussion changes, and becomes more complex. Modern batteries that power electric motors (usually lithium-ion) ensure maximum efficiency in the ordinary recharge and discharge cycle, with a slight loss on a monthly scale of between 1 and 3%. Doing so can last up to 8-10 years . But if the car remains stationary for a long time – and the health emergency imposes long stops on vehicles – the batteries could be damaged.
The beauty is that the batteries are damaged both by keeping them fully charged and leaving them completely discharged. In the first case, the continuous voltage of being always charged will damage the efficiency of the battery, which will deteriorate before and without having been used. In the second, it gets even worse! Because a fully discharged lithium battery, in reality, maintains a small reserve charge, which cannot be used but which produces the so-called “self-discharge” of the battery, that is, it triggers chemical reactions (it loses liquids), damaging it irreversibly. In short, it should be thrown away and it must be seen if it did not cause damage to other components.
So what to do?
You can set the “sleep” function present in many (but not all) electric cars. On the Nissan Leaf there is for example the “deep sleep” function, which hibernates the battery but allows it to power some on-board devices. Tesla recommends keeping the battery connected only to supply the energy needed for the cooling or heating systems of the battery. In the absence of these “sleep” functions, the advice is then to set the recharge to about half of the capacity , and in any case never go beyond 75/80%, so as to avoid any risk of “self-discharge”.
The last tip then concerns the “normal” battery, that is, the 12 Volt one with which we usually power the on-board electrical devices. Let’s not forget it! It may seem counterintuitive, but some electric cars may fail because of this battery. At this point, those who already know that their car will remain idle for a long time, will do well to disconnect this battery, or get the booster cables.