Is There a Problem If a Car's Alternator Gets Wet?
4 Answers
If a car's alternator gets wet but is not in operation, there is generally no issue. Below is relevant information about car alternators: Internal Drying is Sufficient: A car alternator operates at low voltage and will not cause electrical breakdown. Once internally dried, it can be used normally. The alternator serves as the primary power source for a vehicle, functioning to supply electricity to all electrical devices (except the starter) while simultaneously charging the battery when the engine is running normally. Driving Tips: Check Mirrors: Always use turn signals and reduce speed when turning or changing lanes. Before turning, check the rearview mirrors—left turns require checking the left mirror, right turns the right mirror, and both require checking the interior rearview mirror. Avoid Fixating on the Front: On open roads, keep your gaze level and focus about 100 meters ahead instead of staring directly in front of the vehicle. Clutch Usage: When decelerating above 40 km/h, avoid pressing the clutch initially; only depress it when speed drops to around 20 km/h. Steering: Turn the wheel slowly for high-speed maneuvers and quickly for low-speed turns.
Water entering the generator is absolutely a problem. I've worked in auto repair, and this can cause coil short circuits and rotor rust. Once water gets inside the generator, it damages the bearings and carbon brushes, preventing the motor from charging the battery, and may even cause smoking or burn out the circuit. This is most likely to happen when driving through water on rainy days—just a few hours of the motor being soaked can ruin it. From my experience, if you notice signs of water ingress—such as the charging light staying on or unstable voltage—you should stop driving immediately and get it checked. Otherwise, the battery will drain, and the car may stall on the road. The safest approach is to promptly disassemble and dry it or replace the parts. Otherwise, replacing the entire generator could cost over a thousand dollars, which is much more expensive than dealing with water damage.
Remember last time when I drove my old car through a puddle, some water got into the alternator, and after a few days, the headlights started flickering and dimming. The mechanic at the repair shop said the internal windings had rusted and recommended replacing it with a used one. I suggest everyone pay more attention to whether there's any accumulated water under the hood after rain, try to avoid driving through deep water, and if water does get in, don't force-start the engine. Just use an absorbent towel to wipe it off simply before sending it for repair, which can save a lot on repair costs. If left untreated, not only will the alternator fail, but the electronic systems will also be affected, and that would be troublesome. During regular maintenance, check the aging condition of the seals—prevention is the smartest approach.
Water in the alternator is bad news—it can cause current leakage or short circuits. As a car enthusiast who frequently tracks my vehicle, I've seen cases where water ingress corroded bearings and caused unstable voltage output. At best, the battery won't charge properly; at worst, it leads to complete electrical failure and breakdown. Driving through water is high-risk—avoid flooded sections whenever possible. If you notice abnormalities like increased engine noise or dashboard warning lights, shut off the engine immediately for inspection—don't delay.
