Can a car run without a battery once started?

Perhaps you have a flat battery and you figured out to borrow one from a neighbor just to start the car engine and go to the auto parts store miles away for a new car battery… And that raises a question, can a car run without a battery once started? Well, there is a simple and complex answer to this question, and for both the answers are not very promising.

The car battery serves as a smooth power output to the car electronic system. If you turn on too much electronic devices into your car then alternator must work harder to be able to provide enough power to the system. Battery and alternator compensate each other in this situation. If you start the car engine and then remove battery, alternator must work much much harder to produce enough power to the system. Without the battery alternator will eventually die. And there’s more. Alternator produces also spikes and transients, and battery serves as a load dump for this. Without a batter  electronic system such as ECU, radio, air conditioner etc. are in very high danger of getting those spikes and transients on itself and get damaged. Which will eventually leave you standing beside your broken car. So, simple answer is, Yes it can, but… Complex answer comes after the “but”. But you will be in danger to fry your car electronic system.

So, you have a flat car battery? No problem there. Read my experience on how I was able to recondition my battery  even it was completely dead! You will never run out of batteries again, I promise!

Can a car run without an alternator?

The answer is Yes. But it will running as long as the battery have enough power to feed the electric system of the vehicle.

It is really essential to keep a jumper cables in the vehicle. For a different types of vehicles you will get different timings on how long it will run just on car battery alone.

If you driving older car without a lot electronics, and by electronics I mean on ECU and all system that are controlled by the ECU, car will probably run longer just on the battery.

Newer cars will run a lot less because of the ECU systems that controls, monitor and regulate car engine.

This is not suggested because running car on limited power will cause components necessary to operate running car to fail.

Nonetheless, sometimes we need to do what we need to do in order to get from point A to point B to get out of a unpleasant situation.

If you are in this situation where alternator goes bad and if you can chose another way of getting out of that situation, please chose that other way.

Always check your alternator and replace it with a new suitable one.

Alternator plays essential part in the performance of the car by producing suitable volume of power to the battery. It’s best to inspect the alternator at every regular interval and replace it if the alternator is week or bad.

Can a car run with a dead battery?

Before you see an answer go and check my awesome car battery care instructions, and prevent your battery to die prematurely.

It can run. But, you are putting your car alternator to the stress which will affect it negatively, so the alternator could be damaged this way or most likely to die.

And if your alternator dies too, in case you have a petrol engine your car will stop because your alternator will not provide electricity to the spark plugs, In case it is a diesel engine it will run, because diesels don’t have spark plugs, they only have heater elements plugged into the engine cylinders.

In case your battery is dead you can do a push start car down the hill if you stuck there, or you can stop someone passing to help you with a pushing your car.

This way when you put it in a gear your engine will turn on and you can go to the shop or to the safe place, running an alternator without a battery practically.

Now, when you know the answer, you also wanna check my very best suggestion on how to enhance your car battery life in order to last much more longer.

If i disconnect my car battery will it die?

To be able to charge the battery, alternator must produce 14 Volts and above, and the car battery is about 12.6 Volts.

The danger here is, if you disconnect your battery, in fact that the alternator will send those spikes and transients to the rest of the electronic system, and will damage it, and car will stop running. In the old days when cars didn’t depend on electronics so much but had a generator, detaching the battery would cause a voltage spikes and transients which could damage the radio and the ignition system. So once again, car batteries does more than just produce the electric power.

Remember those spikes and transients, alternator will send them to the battery ground and all electronic devices will be safe that way.

Disconnecting the battery will allow spikes and transients to travel around the car electronic system and potentially damage every semiconductor circuit in your car.

Some of the electronics into your car are ECU, radio, electric windows, electric mirrors, cruise control, air conditioner, etc.

As you can see now, disconnecting the battery is very dangerous, because you could do more harm than good, not just to the alternator but the entire electric system of the car.

Does car run off alternator or battery?

This two works together to power the car engine and car electronics. Car engine need a burst of current energy to be able to start.

Device that is responsible for  this power is a battery. Car battery produce sufficient amount of power till the engine starts.

While engine starts, alternator kicks in and start to providing power to charge battery and to power all the other electronic devices built into your car.

Alternator produce electric power needed to run electronic devices such as radio, air conditioner, headlights, turn signals until is more than alternator can produce.

Then battery kicks in and help alternator to produce power needed to the electronics car system.

Now battery takes charge and alternator just charging the battery until power requirements is decreased and sufficient for the alternator, then again alternator takes charge.

To summarise, while car engine running, all electronics runs out of an alternator and charging the battery.

When car engine stops, all electronics runs out of a battery. While engine is running and when requirements for the power raise than what alternator can produce, battery starts producing electric power and alternator just charge the battery.

When you driving at night and if you see your lights output dim, and when you increase the speed you will see higher lights output, which means that your battery getting weaker.

Can you push start a car without battery?

In theory you can, but it all depends on the type of the car, and or is it a newer or older car. There is a problem with the modern cars.

All of them use electronics which are controlled by ECU, the cars brain or just the computer.

And without the car battery no electronic will work. And by electronic I mean on spark control, fuel injection and so on.

Even this is very difficult and if not impossible, to have sufficient amount of voltage from the generator to the spark plugs of the car being pushed, and also there is a good chance that electronic will not collaborate with the push start method.

You’re better off to jump start the car engine even with the flat battery, because of the battery is in place and terminals attached.

So, the answer is you must try first to really see will it start and can you drive car without battery, because every car is different in one way or another this days.

How long will a battery last with a bad alternator?

With a bad alternator, and lets say a fully charged battery you will probably run a car for a 30 miles or so before battery goes flat and discharge completely.

My suggestion is that if you must use your vehicle with a bad alternator use it when it’s a day, because you will not have to use headlights, also don’t turn on the radio or air conditioner, or fan.

And make sure you bring your jumper cables with you just in case if your car suddenly stops and you have no juice left to start your vehicle.

It is very advisable not to drive car with the bad alternator.

If you can just use the battery juice that is left and take a car to the mechanic to check the problem and replace the alternator for  good.

Once alternator is replaced, take your battery and recharge it on a wall charger for the car batteries.

When it’s fully charged place it inside the engine bay where it belongs, connect the plus and minus terminals, and use like alternator never broke on you.