Generator Not Producing Power
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Turn off the Generator immediately and do not run if you have high voltage output as this might cause damage to the Alternator.
If your generator has been in storage over 2 months and this is the first time you have not had power from the portable generator, please click here for the relevant guide.
If there was no smoke or electrical burning smell coming from the alternator, then the majority of the time (over 85%) it is either the AVR or Capacitor beginning to fail, depending on which is fitted to your Generator. Replacing the AVR or Capacitor should fix the problem, but please be aware that a blown AVR/Capacitor may not be the fault, but may indicate a fault within the alternator or an overload surge.
If you replace the AVR/Capacitor for a second time, or believe the faulty AVR/Capacitor is the result of an underlying problem within the alternator, please run the tests at the bottom of this guide.
The most common reasons for failing:
1) Overloading the generator – Breakers do not protect you from overloading, only from surges.
Be sure to take surges into account when calculating what can be run on your generator. Please be aware many things with a motor could have as high as a 100% surge value to their running watts (i.e. Fridges/Freezers, Compressors, non-soft start AC). Also, be aware, most things that produce heat are at least 1500w (i.e. coffee maker, hair dryer, kettle). Also, welding often requires higher currents than portable generators will produce, it is better to use a welder generator than to power a welder with an ordinary portable generator where overload is very likely.
2) Starting the generator with equipment plugged in and breakers on – Turn off all Breakers and unplug all the equipment when starting (This is a very common reason for overloads!).
3) The Generator was not grounded. All generators should be grounded during operation as per instructed in the manual. If there is a surge it needs to go to ground to prevent damage to the alternator and prevent electrocution!
4) Equipment powered by the generator has an electrical fault and is surging beyond the capacity of the alternator. – All equipment should be tested on a regular basis. If you can smell the electrical burning scent around equipment, or issues only happen when certain equipment is plugged in, this is a good indication of an electrical fault within that equipment, or the equipment may require more power than the generator can produce.
5) The generator was manufactured or fitted with an inferior quality alternator and this has degraded – This is not uncommon on budget generators.
6) Your generator is unbranded, rebranded, and is not actually the Wattage it has been marketed to be – This is common with cheap generators bought on eBay, Amazon, random small websites or from “on the side of the road” independent vendor types. If you think the generator is small in size or very cheap compared to other similar wattage generators, there is a good chance it has been incorrectly labeled as a larger generator. Please contact us for more info and we may be able to identify it for you.
7) You have a single phase generator that has been rebranded as a 3-phase generator – Again, common with cheap generators bought on eBay, Amazon, random small websites or from “on the side of the road” independent vendor types. A common feature for some of these incorrectly marked generators is a red socket on the control panel. Please contact us for more info and we may be able to correctly identify it for you.
Alternator issues - It's complicated!
Alternator issues are difficult and complex. Here are some articles that go into more depth for advice dealing with common alternator problems.
Only replace the part with a quality Grade “A” replacement that is built for your Generator.
Cheaper parts could surge and cause damage to your Alternator, resulting in the Alternator needing to be completely replaced, a very, very expensive repair! This is why we only sell maintenance quality grade “A” products.
Do I have an AVR or a Capacitor?
Use the table below to determine where to find the part on your Generator. Once you have identified whether it is an AVR or a Capacitor, you can look up and purchase your replacement parts on our website.
5 or more wires = AVR and Brushed alternator. Search AVR by Generator Brand and Model.
If you have an AVR on your Generator we also suggest you check the Brushes (see below for specific information on brushes).
If your engine stops when you turn on the breakers or you are getting approximately half power, please submit a support ticket for more help.
**If your engine stops when you turn on the breakers or you are getting approximately half power, please choose “I need more help from an Engineer” at the bottom of the page.
Where to find the AVR/Capacitor
If your Generator sits in a frame, it is most commonly behind the end cover of the alternator. In rare cases, it can be found behind the control panel, follow the wires up from the alternator. It will be held on with either 2 bolts or a cable/zip tie. Replacing this should fix your problem.
Super Silent Generator
You can usually find this behind the rear panel of super-silent units. In rare cases, it will be located at the end of the alternator, if so you will need to remove the exhaust system to access it. It will be held on with either 2 bolts or a cable/zip tie. Very occasionally, manufacturers run very long wires to position the AVR so it is accessible through the service panel. Replacing this should fix your problem.
2 Stroke/Cycle Generators
In most cases, the part will be found behind the control panel. To locate it, remove the fuel tank. It will be a black box with 2 wires going to it and may be held on with 1 bolt. On some occasions, you will find a white cylindrical Capacitor instead. Replacing this should fix your problem.
Brushes are only found on alternators with an AVR (If you have a capacitor please go to next section).
Be sure the Brushes are connecting to the Slip Rings correctly. They should have 13mm of the Carbon rod connections (both of them) protruding when removed from the alternator, be the same length and have a gentle curve to the end of them, to allow a good connection. If they are worn or not connecting correctly they will stop power from being produced, or create power intermittently. It is recommended to replace the Brushes at the same time as your AVR, especially if you had a high output fault, as any surge from your AVR may have softened the carbon connections. One thing to be aware of is possible carbon buildup, on or around the slip rings. The worn carbon, from the brushes, must go somewhere, cleaning this off may lead to better operation.
If your brushes have melted this is an indication of one of the following:
– Alternator overheating due to low airflow.
– Alternator overheating due to an overload.
– Alternator failure.
In each case, we highly suggest you run the test below as it is highly likely that the alternator has been damaged.
Alternator Testing on a Portable Generator
If your generator experienced any smoke or electrical burning smells from the alternator, or you have replaced the AVR/Capacitor for a second time, or just wish to test your Alternator to check there are no other faults. Our founder invented a new easier way to test all modern Portable Generators! No need for the manufacturer’s expected readings with “The Beagley Alternator Test” Technique.
We have a training video to teach you the technique. It will guide you through testing and allow you to diagnose other problems that may exist in the alternator.
For Capacitor (brushless) Alternators, please skip the brushes parts of the test.
If you have run these tests, or just want feedback, our Engineers are happy to help! Open a support ticket with them below.
*Did you know? If you wish to test your Alternator to be sure there are no other faults, we have created training videos and posted it at the bottom of the replacement AVR and Capacitor web pages. These can guide you through testing and allow you to diagnose any other problems which might exist in the alternator.
If you have run these tests and want feedback from an engineer, please contact us below. We are always happy to help.
What would you like to do now?
Buy parts and fix the generator
Search for AVR or Capacitor by Generator Brand
See common Generator Capacitor range
I need more help from an Engineer please