Bad voltage regulator
Low voltage from battery
Voltage regulator or loose wire.
they will test it for you at napa. Check the voltage at the battery terminals with the engine off and running. The voltage should increase and be greater than 12.
Bad Alternator or the Battery possibly is losing voltage. I replaced the alternator and serpentine belt before thinking it was the battery. The battery was only 16 months old. But it turned out to be the bad source.
One possible cause is a defective alternator, Have the charging system checked.
What type of battery do i need for a 2002 ford focus
Check if there is voltage to the starter "S" terminal (if starter does not have the small wire, ensure the starter relay is working). Go from there
Alternator is rated at 110 amps. The alternator should provide the voltage required to run the engine. It should handle the system current load. Check the alternator if there is a charge voltage. Turn the engine off and measure the voltage across the two battery terminals with a DC volt meter. Start the engine and measure the voltage across the battery terminals. Look for an increase in voltage on the volt meter. Typically it can go as high as 14.7 volts. If the voltage stays the same as when measuring the across the terminals with the engine off, the alternator is probably bad. If the voltage is charging but not much higher than when the engine is in the off position, some diodes could have burned out in the alternator. Also check the charging wires and ground wires coming from the battery.
sure connect the positive terminal directly to the booster battery and the negative battery terminal to the body
The regulator is within the alternator
good question i have a focus and its rpms jump all the time...i ask my mechanic what was doing it and he replied carbon build up....its very common with ford focus. Try putting higher test gas in your vehicle
how to open and change the battery of ford focus 56 reg