Car jump starts but won’t stay running
You successfully jump started your car and engine started right a way. After removing jumper cables the engine started to slow down and stopped or when trying to drive away the car just turned off.
It is very confusing when car starts with a jump start, but then cut off when you take the jumper cables off. Here are two possible reasons why your car doesn’t stay running.
Reason #1
You have alternator issues like a bad alternator, a bad relay or fuse, broken or slipping alternator belt or loose, corroded wiring.
Your alternator is charging your car battery when engine is running. It keeps it fully charged when driving and powers all the electronics in the car.
When alternator is not working properly, your battery will eventually runs out of power and car dies. A jump start from another car will charge it enough to start, but after you remove jumper cables the power runs out again and car stops.
Reason #2
Battery is too weak to power essential vehicle components like ignition coils, fuel pump and electric power steering. Many newer cars have electric power steering that puts large draw on the battery. If battery is bad (lower capacity) or not holding enough charge, the car turns off each time you try to use A/C or Power Steering. Getting new car battery will solve these problems.
How to tell if bad alternator or battery?
Most vehicles will stay running with bad battery in them or even the battery is disconnected. If alternator and voltage regulator are working good, most cars you can drive with bad battery they will stay running. If you have a red battery light stay on while driving it’s usually a warning that alternator is not recharging your battery.
If your car starts after jump but won’t start again after you drove 15 minutes, then its 90% chance that you need new battery and current battery in your car just not taking in any charge.
What to do after jump starting car?
When vehicles stays running after jump start you will need to drive it for at least 30 minutes until you can attempt to shut it off and try to restart the engine. Half hour is usually enough to fully recharge good battery and if car was able to restart – your battery is still good. Each time you completely let car battery discharge below 6 volts it diminishes the capacity and battery life. It is a higher chance that car battery may not recover after jump start and may need to be replaced soon.