Can a bad alternator cause a bad battery?

Can a bad alternator cause a bad battery?

But, before you condemn it, run a voltage drop test between the alternator and battery. GM typically runs a fusible link wire between them for overload protection and they can go bad, mimicking a bad alternator. A voltage drop of .25 volts or less is Ok and the alternator is bad.

Why does the Volt gauge go up and down?

The voltage always fluctuates, goes up and down depending on how much current is being used by the accessories, and the engine rpm, the charge state of the battery, the ambient temperate, all affect the voltage. Fluctuation is normal, it’s like the stock market.

What happens when you change the batteries in a thermostat?

In most new electronic thermostats, the batteries are used to power the memories in the thermostat to hold the user settings if the power fails. A small battery on the thermostat performs this function for a few minutes while you change the batteries.

Can a alternator charge a battery after a jump start?

Alternator is not designed to charge up a battery but only top it off while headlights etc are on. After a jump start (which you should never need or do) you MUST put that battery on a charger for 12 – 24 hours. A battery that has gone dead twice for any reason is no good.

What causes an alternator to over charge a battery?

Measure voltage across the battery with your DMM. You should get 0.5 to 2 volts higher than base voltage. If you are getting more than 2 volts above base voltage, most likely your alternator is over-charging the battery or the battery is faulty. Other potential problems are a faulty voltage regulator or a problem in the charging system wiring.

When to troubleshoot an unusual voltage system drop?

Troubleshooting for Unusual Voltage System Drops Usually, the first sign that your charging system is in trouble is a “battery,” “ALT,” or “CHARGE” warning light illuminating on your instrument panel while driving. It means that for some reason, the alternator has stopped charging the battery and your car is running on battery power.

What happens if you replace the battery in your car?

This can cause something minor, like the clock to lose its time, but it can also lead to engine stalling or even a failed smog inspection. In order to avoid this issue, it has become more and more critical that power is supplied to the electrical system while the battery is disconnected, for any reason, including replacement.

What to do if you have electrical issues after replacing a battery?

If you’re experiencing electrical issues immediately after a battery replacement or disconnect, make sure the battery cables were re-attached and tightened down properly. Herculean strength isn’t necessary, but the cables should be snug and not move around or come off of the battery posts.