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More Home made generator projects.

Here is a strange project that comes in response to a customer request.

Q: Is it possible to run two alternators off the same engine?

A: Yes and no.

However, several customers have had special requirements for running alternators of different voltages to different battery banks, also of different voltages.
 

Take the situation above for example:

Pretty cool!

A poor man (or resourceful man's) AC powered DC battery charger!

For some time now we have been developing gas powered DC charging systems with great success, and have even been offering components for folks to be able to build their own.  What I really needed was something I could just plug into the wall to charge a battery in a car that was buried deep in the back of the warehouse and to avoid fumes from an engine.  What I came up with that day was a battery charger made from a 1 HP AC motor and a car alternator!  Yes, having one of Epicenter's generator brackets made it come together in no time.  As luck would have it, we had a few special brackets that have a bolt pattern that fits a wider range of motors, and it came really close to fitting the bolt pattern of the front of the AC motor.  In a few minutes with a file, the pattern was adapted and presto. The short version of the bracket shown is not available at this time, but our longer version could be used but you would have to drill your own holes to adapt the bracket to the AC motor.
 
 
 

AC motor, GM alternator, pulley, belt and one of our brackets!

The ultimate DC charging system!

Direct Drive, and Propane powered.

Please note that we no longer offer propane conversions. Do not call about propane conversions!

In this project, the customer wanted to direct drive an alternator to a 5 HP motor.  This was not a simple task.  The first thing that was required was to have custom direct drive couplers made that would take the place of the pulley and nut on the front of a standard alternator.
 
 

Notes on the drive coupler:

To complete the coupler, you then select the size that fits your motor shaft.   The combination of the special alternator coupler, a rubber spider (shown above), and the motor shaft coupler works to transfer rotational energy from the motor to the alternator shaft.
 
 
 

Direct drive mounting assembly.

The next thing to do was to come up with a way to mount the direct drive system to the engine.  Not an easy task to say the least.  To make a long story short, we needed two plates.  Shown here is the complete assembly.  One plate had to mount to the engine (the plate on the bottom). That plate has mounting slots such that it can fit all engines with bolt circles smaller or equal to 7.5 inches.  This covers everything from 3 HP to 20 HP.

Now, here is the trick.  Notice from the picture that there are spacers and bolts connecting the two plates.  Well, nuts had to be welded to the side of the motor plate that faces away from the motor.  This was done so that the surface of the plate that touches the motor could be free of obstructions.  The spacer tubes then need to be large enough in diameter that they can sit over the nuts (the nuts sit inside the tubes).  In the example shown, we used square tube for the spacers but we have also used 3/4 electrical conduit for the spacers. The length of the bolts and the length of the spacers must be determined at the time of assembly; knowing the exact length of the motor shaft is crucial to make certain the bolts are long enough to go through the spacers into the welded nuts without being so long that they go through the nuts and touch the engine case.  The length of the spacers is also critical in setting the space between the shaft couplers for the rubber spider.

Note that we do have a limited production run of these bracket sets available but you will need to determine the length of, and make your own spacers and get your own bolts.  The brackets do have the nuts welded in place for you.
 

Pressure washer cart used to mount it!

The last task is to come up with a way to mount the system. What we used was a pressure washer cart. One thing to note: This is a charging system and not a generator.  So, it has to be connected to a battery to make a complete system.  Connect a DC to AC power inverter and you can then get AC out of the system, but the battery is not shown.

I guess someone could make brackets to hand a battery off the back of this to make it a more complete system, but the intent of this project was to be able to have a very mobile charging system to charge batteries at a stationary location (not to carry the batteries with the system).

Now some final notes on the direct drive model. Use a 94 amp alternator. At idle (about 1700 RPM) the alternator is able to output about 20 amps. Crank up the RPM to full throttle (3600 RPM) and it will do about 70 amps. Our first attempt was with a 63 amp alternator and the 5 HP motor was happy to keep running even as we overloaded the alternator and smoked the diodes. So, use a 94 amp alternator and you will have a bit of reserve at 3600 RPM (to put out more than 70 amps the alternator would actually need to turn faster than the motor can go so it's like having a built in safety governor).

Re-introduction of our famous horizontal generator bracket!

Back in stock after several years!

One of the handy enhancements was the addition of two vertical slots at the bottom of the bracket.  These slots allow the use of right angle brackets to tie the main bracket to your base.  This solved the issue of vibration in the original design.

As you might remember from an old tip of the week, we designed this bracket for engines that had obstructions on one or both sides of the motor which would require a longer bracket to get the alternator away from the obstruction. The bracket also had an area that was cut out to clear side mounted gas tanks.

Shown here is an example mounting using a 5 HP OHV Tecumseh engine.

To see some other versions of this project, please click here.

An improved mounting scheme.

DC to AC power inverters are available through these pages.

If you would like to be notified when additional information is available, please fill out the following form. We will notify you when additional details are finalized and are available. Just fill in your E-mail address, and push the button!

Wiring it up:

The wiring depends on which alternator you choose. All three alternator types are shown.
Do not wire the alternator unless you are sure about what type you are using. If you make a mistake in the selection of the alternator or wiring diagram you run a very high risk of damaging your battery, electronic devices, or worse yet causing personal injury! Consult a parts professional for additional information!
 

This Tip o'da Week is intended for educational purposes only. No guarantees are expressed or implied as to the accuracy of information presented here! Consult with an automotive wiring expert before attempting to carry out any wiring.

One final note:

If you are using an alternator that requires an external switch, you will need to turn off the switch prior to attempting to start the generator. Once the motor is running, the switch can be set to the on position.
 

For folks interested in items mentioned in this tip, they may be ordered directly from this tip until they have been incorporated into our product pages.