You can test to see if the alternator is overcharging, using a simple voltmeter.

Battery. Alternators that overcharge will typically produce excess voltage to the battery, making the battery case swell up, become very hot and lose its electrolyte through boiling. This surge disrupts the wiring in the alternator, causing an overcharging condition.

A voltage regulator is usually part of the alternator, and is used to keep a steady flow of voltage to the battery. If the voltage regulator is defective, it will send either too little or too much charge to the battery.

1. Start your vehicle and open the hood.
2. Locate the vehicle’s battery.
3. Turn the digital voltmeter on and adjust it to the proper settings, if necessary.
4. Connect the clamps or leads of the voltmeter to the battery.
5. Examine the voltmeter.

Alternators that overcharge will typically produce excess voltage to the battery, making the battery case swell up, become very hot and lose its electrolyte through boiling. Improperly jump-starting the vehicle can send a surge through the battery that destroys one or more cells in the battery or shorts it out.

Overcharging causes excessive heat to be produced in batteries which can cause explosion, melt-down, boiling away of acid, premature corrosion of electode plates within the battery cause premature failure of the battery, the elctrodes can warp inside the battery and short out the battery and take all the electronics in …

A car’s battery will overcharge if the voltage regulator isn’t working correctly. A voltage regulator is usually part of the alternator, and is used to keep a steady flow of voltage to the battery. If it sends too much, the car battery will overcharge.

Pro tip: a good rule of thumb to help avoid the trap of overcharging is to make sure you charge your battery after each discharge of 50% of its total capacity. If the battery will be stored for a month or more you should charge to full capacity before storing and then charge throughout the storage time.

Use A Multimeter When the vehicle is started, without the introduction of a load (the lights or air conditioner), the volts will usually rise to an average of 14 volts. If the multimeter reads at more than 14.8 volts, then this can be considered as overcharging.

about 12.6 to 12.8 volts

Connect a voltmeter across the battery and resistor to measure the battery voltage during discharge. Stop the discharge (disconnect the resistor) when the battery is down to the desired voltage.