All About Delco-style Alternators for Use in Wind Generators

If you're new to idea of building a wind generator out of re-purposed components, then you've probably asked yourself a few of the following questions:

  • Why are car alternators appropriate for wind power?
  • What modifications are necessary to make a practical wind generator from a car alternator?
  • Why are Delco-style alternators so popular?
  • Which WindyNation blades best match with wind generators using Delco-style PMAs?

Well, maybe we threw in that last question ourselves! But either way, if you've every had questions about using re-purposed car alternators, here's your chance to read all about it.

Around the world, it is increasingly popular to find wind power enthusiasts taking advantage of excess supplies of alternators or motors originally designated for doing things other than making electricity from the wind. In Australia and New Zealand, Fisher & Paykel washing machine motors are enormously popular, since these washing machines use large permanent magnet motors. In North America, Ametek, Inc. is known for its tape drive motors, which until recently were widely available and extremely popular for making wind generators.

But perhaps no other brand comes up as frequently when it comes to DIY small wind power as the Delco brand of permanent magnet alternators.

Why are Delco-style Alternators So Popular?

The Delco name comes from the Dayton Engineering Laboratories Co, a long-time supplier for the General Motors Company. Delco had a long and storied history including developing the first reliable battery ignition system. The company was incorporated into a number of larger mega-corporations, manufacturing hundreds of vital components that went into American-made automobiles. And though GM continues to use the Delco brand name, including for its ACDelco parts division, the company has evolved considerably since it’s early pioneering days.

Since the early 80s, there has been a tremendous amount of excess manufacturing capacity in the American auto industry, which often went into making a lot of components that didn’t necessarily find their way into cars. These alternators that didn’t find a home under a hood still ended up finding a way to be useful. For wind power enthusiasts, Delco has experienced a renaissance. Re-purposed car alternators have become extremely popular and relatively cost-effective for use in small wind generators.

Most ACDelco generators that you find sold for the express purposes of being a wind generator have been re-purposed or refurbished. The reason for this is that a Delco car alternator operates under a different set of conditions when used in a wind turbine--at least as compared to a permanent magnet alternator.

What Modifications are Necessary?

A car alternator’s stator is wound to operate at very high RPMs, mostly because the alternator in a car has the luxury of being turned by a powerful, high rpm engine. The operating rpm of a Delco car alternator is around three times the rpm of the car engine’s crankshaft. A car’s crankshaft generally operates at around 1000 - 4000 rpm. For this reason, a Delco car alternator is designed to put out good charging voltage and amperage at around 3000-12000 rpm.

By comparison, a small wind turbine with a roughly 60-inch diameter rotor might hit 850 rpm in 25 mph wind! 850 rpm is far below the threshold for a standard Delco car alternator to even start charging a 12 volt battery bank!

When one uses a Delco car alternator as a wind generator, it is absolutely necessary to modify the alternator to operate at low RPMs. This is accomplished with two intricate modifications:

  1. One replaces the stock Delco car alternator stator windings with a stator that has more turns of smaller gauge wire.
  2. High powered Neodymium magnets are placed on the rotor which gives more power output than standard magnets.

[If you are new to wind power, you should read our article How to Choose a Motor to learn about why rpm and voltage are so important for proper battery charging]

Where Can I Buy Quality Delco Alternators for Wind Turbines?

There are a few reliable and responsible companies that sell these popular Delco or Delco-style alternators that have been modified to be suitable for use as wind generators. The only one we would specifically recommend is WindBluePower (

WindBlue makes good quality Delco Permanent Magnet Alternators (PMAs), and they are ethical and honest in how they assess and present the likely power output from these PMAs. They do this mostly by presenting a Power Curve demonstrating output from their alternators under load. This contrasts with some other re-sellers of modified Delco PMAs who only present open-circuit voltage readings, which is a virtually worthless measure of the output of a PMA.

For more information on why open-circuit voltage isn't a fair assessment of the power output from a PMA, check out Terry Galyon from TLG Windpower and his helpful podcasts about practical wind power on the Green Talk Network.

Have Reasonable Expectations

When it comes to Delco alternators, it’s really important to have reasonable expectations about the kind of power you’ll produce from these units. In other words, you should not expect a power production miracle from a Delco PMA for the simple reason that the amount of power a wind generator or alternator can make scales with:

  1. The amount of copper you can fit into the stator
  2. The amount/size of high powered neodymium magnets that can be placed on the rotor.

A Delco car alternator is about the size of a cantaloupe fruit and so there is a limit of how much copper and magnets that can fit inside of it.

Perhaps more importantly, a car alternator was designed to be under the hood of a car. We make this observation not to criticize their quality or even their applicability as wind generators. It is a simple fact that the specifications for a car alternator are dramatically different from a wind generator. For example, a car alternator will not be weather-proof, since they are usually well-protected from rain and mist because they are under the hood of a car. Second, as we’ve discussed above, the stator must be rewound in order to produce a voltage suitable for battery charging. Third, a car alternator does not need to be highly efficient at generating electricity because it is being turned by the car’s engine which can produce at least 100 hp (76000 Watts!).

Great Way to Learn How to Build a Wind Generator

That said, we are encouraged by the thousands of people who learn the fundamentals of wind power from Delco PMAs, and who are indeed producing meaningful amounts of electricity from such units.

We’ve tested WindyNation blades on a few different kinds of WindBlue alternators and we wrote this next section with the intention of creating a useful resource for customers who might be interested in using WindyNation aluminum wind turbine blades with a WindBlue alternator.

We tested several sets of our blades on the WindBlue 540 and 520 series PMAs. All tests were done using a 12 volt battery bank as the load.

Table 1: WindBlue 540 Used With 28” WindyNation HyperSpin Blades (Set of 3)

Wind Speed (mph) Amps
11-13 2-4
20-25 10

We found that the WindBlue 540 performed respectably with 3 of our 28-inch HyperSpin blades. We measured about 2-4 Amps of output into a 12 volt battery bank in about 11-13 mph winds. In very high winds (20-25 mph), we measured about 10 amps of output into a 12 volt battery bank. The HyperSpins are best-suited for the 540. The 540 PMA is wound for high voltages at low RPMs so that it can reach charging voltage in low to medium winds. As a consequence, the unit does suffer a little in terms of Amperage output.

Table 2: WindBlue 520 Used With 28” WindyNation HyperSpin Blades (Set of 3)

Wind Speed (mph) Amps
12 3-5
20-25 12-17

The WindBlue 520 was best paired with the 5-blade HyperSpin set, which provides a nice combination of torque and speed. This alternator gives better amps than the 540, but it doesn’t start charging a 12-Volt battery until you have a very steady 9 mph wind. At about 12 mph wind, the alternator was able to produce 3-5 amps. In 20-25 mph wind, the 540 was producing 12-17 amps which is a respectable amount of power for a small PMA.

All in all, we were impressed with the performance of WindBlue's alternator. If you are set on using a Delco on your wind turbine project, then we would recommend you go with a WindBlue. If you are looking for something more powerful, then we would of course direct you to check out our Windtura 500 PMA.

The appeal of modified Delco car alternators for do-it-yourself wind power should be clear to anyone: LOW cost.

Thousands of DIYers around the world use these units for making small and really cost-effective wind turbines. When purchasing a Delco-style alternator, it's important to have reasonable expectations about the power it will produce. Furthermore, because of the refurbishing necessary to "rebuild" the Delco alternator for use in a wind turbine, it is important that you purchase a Delco alternator from a reputable and honest company. A Delco car alternator that is modified by an unskilled person or a company that cuts corners will suffer from horrible performance, cogging, and will most likely eventually fail on you.

Good luck building! And if you have any questions about a Delco-style car alternator, feel free to email us at!

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