In order to convert a Generator to an Alternator on your Chevrolet, some understanding of how they work and are wired is required. You should also own a good digital multimeter for accurate testing of all components in your car or trucks electrical systems. An Alternator is a generator that produces alternating current (AC) by converting mechanical energy to electrical energy. The Process of rectifying the AC current into DC current is handled by diodes inside the alternator. Alternators are generally simpler, more reliable, and can be more efficient than direct current generators. Alternators generate electricity by the same principle as DC generators. When magnetic field lines cut across a conductor, a current is induced in the conductor. Just like Generators, Alternators are used in automobiles to charge the battery and to power all the electrical systems when its engine is running. In the early 1960’s GM dumped their old generator system in favor of an alternator. The little 10DN alternator was much more compact than the old generator and used a small regulator that mounted to the firewall or one of the fenders. This early type of GM alternator was rated at around 61 AMPS and referred to as externally regulated. By 1969 GM introduced the Delco 10-SI Delcotron alternator with its internal regulator on the Corvette and started offering it as an option on certain models. Within a few years the 10-SI was standard equipment on all GM cars and trucks and it too would eventually evolve into newer models. The SI series alternators are typically found on cars of the 1970s and early 1980s and usually have a single grove pulley. 3-Wire vs. 1-Wire Alternators Among the GM SI series alternators, there is both the 1-wire and 3-wire type with built in regulators. For most applications, the advantages of a 3-wire alternator will far surpass a 1-wire installation. Both types have an internal regulator but it’s surprising how much stronger HEI ignition systems work at 14 volts compared to 11 or 12 volts. The same is true with a Vintage Air system, headlights and electric fans etc. The 1-wire alternator only has a heavy gauge wire connected from the alternator output terminal to the battery. The one big advantage is that not much knowledge is needed to wire it into an electrical system. These alternators have been widely used on marine, agricultural and industrial applications such as boats, tractors and forklifts. They are best suited for applications that need the alternator for charging a battery only. The main difference between the 1-wire and 3-wire alternator is in the internal voltage regulator. The voltage regulator for the 1-wire alternator is often referred to as self-exciting. After the engine has been started, and the alternator is spinning a small amount of current is developed to turn “on” the regulator. Sometimes the engine has to be revved up once or twice to excite the regulator. Other advantages of a 3-wire alternator are, you can operate a warning or Idiot Lights on the dash, 3-wire alternator regulators use remote voltage sensing, availability is much better, and they cost less. I do not recommend using a 1-wire alternator on your classic 1950s or 1960s GM automobiles you may be converting from a generator to an alternator. When most if not all the factory wiring can be used in your generator to alternator conversion, why not use a 3-wire alternator. Even an intended up-grade to a 100 amp 1-wire alternator can result in dim lights, weak ignition and weak performance, all due to a lack of Remote Voltage Sensing. Remote Voltage Sensing, a 3-wire Advantage Remote voltage sensing is a must for good electrical system performance. It lets the voltage regulator make adjustments to the electrical system in order to maintain a system voltage of 14 volts. Remote Voltage Sensing is not a new idea. In fact many factory original systems have been using it for years. Even with the 10DN alternator and external voltage regulators back in the 1960s. The alternator voltage regulators constantly monitor the voltage level of the system. For most temperatures and conditions, the textbook battery voltage level when topping off a fully charged battery is about 14.2 volts with a 12-volt system. The voltage regulator will adjust alternator output to maintain 14.2 volts at the battery under normal operating conditions. Therefore, most electrical system parts, lights, ignition, and accessories are designed for best performance when operating at about 14 volts. To deliver power to various parts of the electrical system, some of the wires will be long in length. Most often, the dash area with switches and fuse box is far from the alternator. And under the hood, the battery may be at the opposite side from alternator mounting, which will also require a long wire. Long lengths of wire will result in a “voltage drop.” The key to good performance is to let the voltage regulator make adjustments to the voltage level sensed at the battery. Then other parts of the system will follow the voltage level maintained at the Battery. This is Remote Voltage Sensing. See diagram below of a typical 3 wire alternator with Remote Voltage Sensing!! Tip: Never remove the connection at the battery when the engine is running. You will do serious damage to your trucks electrical system, as the alternator voltage regulator senses no battery voltage.
Alternator Upgrades Good article there , a couple misconceptions . FWIW , the Delcotron alternator was fitted to 1962 and subsequent Chevrolets , it was a 35 A. unit and that was sufficient to run the engine , gauges , quad headlights , AC , radio and still had plenty left to keep those old tar topped low CCA batteries well charged for easy staring in sub zero temperatures . The primary difference between a Generator and an Alternator is : the charge current is passed through the brushes in a Generator whereas in an Alternator the charge current passes directly from the field windings (now called the ' stator') into the diode triode for rectification into DC current & thence into the voltage regulator . The correct terminology for an Alternator is " AC generator " ~ GM still writes " Generator " on the box , parts list and invoices when you buy a new Alternator , I just ordered up one yesterday and this nomenclature always makes me smile . The so called " One Wire " alernators were in fact designed to use two wires and an idiot light , they can be installed with only a live battery wire but they'll charge sooner and higher at lower RPMs (means @ idle) if you connect an ignition source with to the unused (exciter or signal) terminal . on older vehicles you'll need to install a diode in ths wire else the engine won't shut off when you turn off the key . This alternator is cheap and reliable , I use one on my '49s 235 , two wires of course . it was fitted to late 980's Chevy V- equipped vehicles (and many more) making it dead bang simple to find in any FLAPS , Junkyard or Service Station anywhere in America . The drive shaft is a standard size so just swap your Generator's pulley over to it and toss the Serpntine Belt pulley in the trash where it belongs anyways. Lastly : a word about field testing chaging by disconnecting the battery's gound cable : it WILL NOT damage your alternator nor generator ! It CAN'T . the damage is done when you re-connect the ground cable as the alternator / generator has been charging flat out thinking the battery's dead so when you re-connect it , it " spikes " and this often blows the diodes out , even in heavy duty units . This is yet another reason to always disconnect the ground cable first and to re-connect it last , NEVER the hot cable . If you need to make an emergency field charging test , start & run the engine then disconnct the ground cable and tuck it down behind the battery ~ if the engine continues to run , the alternator / generator is charging fine , go 'round and shut it off then re-connect the ground cable . as you've used the ground cable , there's no worries about sparks and dead shorts of the cable touches the frame or body . I hope this helps , alternators are great as they charge @ idle speeds whereas a generator doesn't . For the purists , get a generator from a '54 Pontiac or Caddy for high output 6 volts or if you have a 12 volt setup(or task Foce Truck) get the generator from a 1960 Caddy...
Great Subject Matter Guys! Dorcutt, BlueFlame and VWmatt, I read both threads and great information, I also like the three wire alternator to. During my time internet surfing I came across this wep page with some detailed graphics on this topic. I hope you fine of some use. http://www.autoshop101.com/trainmodules/alternator/alt101.html
