Identifying the Appropriate Alternator.
|This project is dependent on a specific alternator for success, which can usually be found on a Camry or something similar. It is a Denso product, with a bifilar stator winding. Here's a picture with the end cover, regulator, brush assembly and diodes removed. Note the distinctive and very heavy mounting "tabs."|
|This photo shows the label on this alternator, but you don't need this specific model. Several of the Denso higher-current models use bifilar windings. This one has a case diameter of about five inches (excluding the mounting tabs), and a case length of about 3.75 inches (measuring the aluminum case only). The distance between mounting tab holes is roughly six inches.|
|The specific feature you want to look for is a bifilar winding on the stator. If you get the angle right, you can look between the cooling slots and see that at several of the terminals there are two wires attached, and at one there are six. That's because each pole piece is wound with a "double" (bifilar) wire, and this provides a nice opportunity for us. This bifilar wire allows the alternator to pass very large currents (double what a single wire would), but we are not likely to need this current capacity on a windmill. What we lack is voltage, and a simple re-wiring at the terminals allows us to change the existing parallel windings into serial windings, thus doubling the voltage output. Be warned that not all Denso alternators use bifilar windings, you need to check. At right is a closeup of a terminal (cover, etc., has been removed) showing what are actually six (three bifilar) wires entering the terminal.