Alternator in California

Heat is what ends an alternator here

An alternator is an electrical machine bolted to the hottest part of the car, and its regulator and rectifier diodes are semiconductors with a temperature limit. California runs them above their comfortable range for months at a time, and under-bonnet temperature is always well above ambient — a ninety-degree afternoon is a great deal more than ninety degrees at the back of the case.

What that produces is not a dramatic failure. It is a regulator that drifts, so the charging voltage wanders, and diodes that leak, so the output ripples. The battery then lives undercharged and gets blamed first.

The connections corrode before the machine does

Damp air works on the exposed side of an alternator: the terminal stud, the plug on the regulator, and the earth strap between engine and body. A resistance in any of those looks exactly like a failing alternator on a meter at the battery, and is a fraction of the price to fix.

Check the charging voltage at the alternator's own output and then at the battery. A meaningful difference between the two is a connection, not a machine.

Coastal air carries salt inland far enough to reach cars that never park by the sea.

The climate, in a number

Fresno averages 38.4 days a year at or above 100°F on the 1991 to 2020 normals. Every one of those days is a day the cooling fan, the air conditioning clutch and the blower are all drawing at once, and the alternator is what carries them.

What goes on the roads in winter

Anti-icers, deicers and abrasives go on the mountain routes, and the state's own manual warns that salt on a bridge deck corrodes the structure and should be used with caution. What is spread on the road reaches the alternator through the same wheel-arch opening that cools it, and a case packed with salted grit runs hotter than one that is clean.

Which parts this actually touches

The list is narrower than people fear and wider than they expect.

Not touched: brakes, suspension, steering, lighting, glass, cooling, drivetrain, interior. A control arm is a control arm in every state.

What else California does to a car

No road salt anywhere in the state, so corrosion arrives from the air rather than from underneath.

Sierra grades are long, and the descent is where a brake system is judged.

What we hold, and what it costs

5 options from Bosch, Cardone, Denso, Remy and Valeo, from $239.99 to $309.99. Prices are firm — where we have no price we publish none.

We are a reseller rather than a manufacturer: we source the part, check it over and sell it, and we confirm it against your year, make, model and engine before it ships rather than asserting a fit on the page. We ship anywhere in California, including Los Angeles, San Diego, San Jose and the Bay Area and Sacramento.