In theory, if your alternator is providing adequate power to the car while charging the battery, then once the car is started, disconnecting the battery should not cause the engine to stop running. …
What will happen if I disconnect my car battery?
Disconnecting your car battery will not cause any permanent damage to your computer or ECU (electronic control unit), but it can have some adverse effects. Those include canceling your preset radio stations, forgetting learned shift points, and your car’s ideal fuel/air mixture.
Can you disconnect battery to check alternator?
Tools Required. If you have a newer battery but your car won’t start, you may have a bad alternator. If you’re tempted to test an alternator by disconnecting the negative battery cable, don’t do it. … The second you disconnect the battery, the voltage regulator pegs the alternator to put out maximum power.
Can you drive a car with the battery disconnected?
If the engine’s already running, disconnecting the battery will still keep the engine running. If you’re trying to start a car without a battery or with a very dead battery, it won’t start (even with push start in a manual car) because there’s no electrical supply (spark) to the combustion chamber.
Can I just disconnect positive terminal?
Can you just disconnect the positive terminal? Just be careful and ALWAYS disconnect the POSITIVE terminal first. Keep the battery grounded ( negative is ground). Try not to touch the positive wire on metal as it possibly could be holding some charge after you disconnect it.
Should I disconnect battery if car parked long term?
“If someone is going away for a few months over the winter, they should definitely disconnect the battery. It’s the only way to prevent battery drain,” Rashidi said. … In some instances, more serious issues can arise when disconnecting or reconnecting the battery.
What are the signs of a bad alternator?
7 Signs of a Failing Alternator
- Dim or Overly Bright Lights. …
- Dead Battery. …
- Slow or Malfunctioning Accessories. …
- Trouble Starting or Frequent Stalling. …
- Growling or Whining Noises. …
- Smell of Burning Rubber or Wires. …
- Battery Warning Light on Dash.
Which battery terminal do you disconnect to check the alternator?
Safety: Always remove the negative cable first, then the positive cable. When you connect the battery, connect the positive end first. So the order is: Remove black, remove red, attach red, attach black.
How do I know if my battery is bad or my alternator?
An illuminated dashboard light can indicate a problem with an automobile charging system. However, a very simple way to check if the alternator is working is to run the car and disconnect the positive terminal of the battery. If the vehicle stops running, then you probably have a bad alternator.
How long will a car battery last if disconnected?
When the battery is removed, it can stay for six weeks to 6 months. However, you need to keep recharging the battery over time. Ideally, the battery should be recharged every 12 weeks when the battery is disconnected.
What happens if you disconnect the positive terminal first?
It can fall across either terminal and the car and nothing will happen. If you disconnect the positive terminal first and you drop a spanner, it is possible for it to fall across the positive terminal and any earth on the car, with spectacular and possible dangerous results.
Can you test an alternator with the car off?
First, test it with the engine turned off. Turn the engine off. Turn on your voltage meter and set it to DC volts. Connect the positive lead to the positive terminal (+) on the battery, then connect the negative lead to the negative terminal (-) on the battery.