Alternator in Iowa

Winter is a sustained electrical load

Short Iowa winter journeys ask the charging system for everything at once: headlights against a dark afternoon, the blower at full, a heated rear screen, heated seats, and a battery that has just given up a large amount of current to a cold start.

An alternator that is merely tired copes in July and cannot keep up in January. The symptom is a battery that goes flat repeatedly and tests fine each time it is charged — the battery is not the fault, it is the thing reporting one.

Derecho winds and hard winters in the same year.

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.

An alternator breathes whatever the road throws up

The case is ventilated, because the machine has to shed its own heat. On unpaved roads that means it is drawing dust through itself continuously, and the dust ends up on the slip rings and in the bearings.

A whine that rises with engine speed rather than road speed is a bearing. It is worth catching, because a seized alternator bearing does not stop at the alternator — it takes the belt, and everything the belt drives goes with it.

A gravel road majority, and washboard is what fades a damper without leaking a drop.

The climate, in a number

Des Moines has a normal annual snowfall of 36.5 inches on the 1991 to 2020 record. 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

Rock salt, salt brine, sand and calcium chloride all get used, and the record season, 2007 to 2008, took 303,316 tons of salt and nearly sixty thousand tons of sand. 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.

The seasonal range

Iowa runs from genuine winter cold to genuine summer heat, and both ends are demanding.

Summer heat destroys batteries. The chemistry that ends a lead-acid battery accelerates with temperature, and a battery under a bonnet in July is running that clock fast. Winter cold is what reveals the damage: at twenty below the battery delivers a fraction of its rated current while the oil the starter must turn is at its thickest.

What else Iowa does to a car

Heavy winter salt on top of a summer of grit.

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 Iowa, including Des Moines, Cedar Rapids, Davenport and Sioux City.