How long can you drive a car powered by a battery - without recharging by alternator?

Modern cars have many consumers in the form of various servos, heaters, electric power steering, as well as electronic control systems in the suspension and braking systems. Electricity in a modern car requires a lot of power, and the alternator is the only one that has to provide it fully and uninterruptedly.

If the alternator fails, how long will the battery last without it to keep the car moving? There is no clear answer to this question. There are too many factors that influence this:

• whether the vehicle is a car or a lorry
• whether the engine is petrol or diesel;
• climatic conditions: winter or summer;
• the equipment of the car, i.e. the number of appliances that consume electricity.

How long can you drive on battery power alone?

If the alternator is not charging the battery, driving the car is quite possible. Some alternators stop producing electricity, under heavy acceleration or at idle speed. However, these are special cases, designed by the car's designers. When the alternator stops working, the battery takes over the load.

The main characteristic of a battery is its capacity. You can also find a parameter on the battery called – reserve capacity. This parameter indicates how long a serviceable and charged battery can deliver 25A of current before its voltage drops to 10.5V. If this parameter is not indicated on the case, it can be roughly calculated by knowing the capacity of the battery installed in the car. For a 65Ah battery, the operating time would be approximately 100 – 120 minutes.

It turns out that a car without a serviceable alternator can drive for about two hours. And how many kilometres can be driven in that time is difficult to predict, depending on traffic conditions.

The following point should also be noted. If the cause of inoperability of the generator is a broken drive belt, it is not recommended to drive further. Because on some engines, together with the generator drive, the engine cooling system pump is driven. And if you continue driving, the engine may overheat and fail.

To prevent such unpleasant events from happening to the car owner, it is necessary to keep an eye on the condition of your car, to undergo regular maintenance of the vehicle, all its important elements and systems. If there are any signs of malfunction, the alternator should be diagnosed. The alternator can be checked at a specialised service.

Equipment for generator diagnostics

The MSG Equipment line of alternator and starter diagnostic equipment includes equipment that can provide a full range of possible diagnostic work:

• Express diagnostics of the alternator on the car, using testers: MS016, MS015 COM, MS013 COM;
• complete diagnostics of the dismantled unit on stands: MS005, MS008, MS006 COM, MS002 COM, MS004 COM;
• For diagnostics of generator assemblies, the following testers are used: MS012 COM, MS014, MS021.

Find out more about the features of equipment for diagnostics of starters and alternators on the website or by contacting the company's managers.