Knowing your Generator (Unstable, Over & Under Voltage)

I take a small portable generator with me when I am using my RC cars this allows me to charge batteries and run power tools such as a dermal or soldering iron for onsite repairs which comes in really handy. I like to be prepared when I take my cars out, nothing worse than driving to the RC track to be heading home 15 minutes later.

Don’t just plug anything into your Generator

A lot of people don’t understand you cannot simply just plug anything into a generator for example laptops and printers. Especially not into the cheap generators like mine.

Cheap Generators v Inverter Generators

There are different kind of generators but the major ones are you typical cheap and you’re more expensive inverter generators.

Cheap generators suffer from unstable power output, over and under voltage issues, they are good for power tools but I wouldn’t plug devices straight into them like laptops unless I am ok with it getting broken. You plug your device straight into the output of a cheap generator there is nothing regulating the output.

Inverter generators work differently, the engine turns a DC alternator producing 12v DC, an inverter then takes this 12v DC and produces 230v AC pure sine wave electricity. This is perfect for sensitive electrical devices. These type of generators do not experience over and under voltage issue either. However they are more expensive.

Unstable Power Supply

In terms of stability the power coming from a generator is unstable when compared to the electricity coming from your house socket. I’m not going to go in-depth into this but the electricity from your house socket will normally come out at around 50hz using sinewave (clean).

Cheap generators normally outputting in a modified sinewave which is bad for sensitive electronic devices (anything with a microprocessor, basically most things other than standard power tools). The power coming out of these generators is very unclean and unstable compared to your house socket. This can easily destroy microprocessors. Not to mention over voltage and under voltage issues.

Over voltage

Cheap generators spin faster the more energy you draw from them. My generator gives out a good 240v but let’s say we have 2 items plugged into this generator, a laptop and a battery charger. The generator is outputting 300w to power both devices. The charger has finished and stops charging, this is where overvoltage occurs, the generator is still outputting enough power for both the laptop and charger, but only the laptop needs powering now.

The generator will begin to slow to output the required wattage but this can take a couple of seconds, during this brief period the generator is outputting more power than required which will cause the output voltage to climb, you can easily see increase in voltage ranging from 300+ easily which will destroy most electrical items (say goodbye to my laptop or at least the charging brick).

Under voltage

Under voltage follows the same principles as over voltage but the other way around, instead of the voltage increasing for a brief period the voltage decreases, the reason for this is due to a sudden increase in required output power, it can take the generator a couple of seconds to speed up to the required output level (if the generator can output that high).

An example the generator is outputting 120w to power a laptop, you plugin in a charger and start charging a battery. Now the total required wattage to power both the laptop and charger is now 300w. The generator will begin to increase speed to output the required wattage but for a brief period of time the output wattage and voltage will not be high enough to power both devices. We are not in a situation where both devices are now being starved.

At first you may be thinking well it just won’t turn on, with modern electronics using microprocessors this is not the case and under voltage can cause unseen damage to electronics. Microprocessors are very specific and require a fine balance or damage internally can occur.

How can I make a cheap generator more friendly?

I wont be held responsible if you blow up your laptop, but there possible solutions to make a cheap generator more friendly for sensitive electrical devices, it is not as simple as just connecting a surge protection socket in most cases this will do nothing as a surge is not the same as a dirty, over or under voltage issue. Most generators have a 12v output you may be able to purchase a pure sinwave inverter, connect it to the 12v output and then connect your electrical devices to the inverter.

I cant state this enough I have not tried this and will not be held responsive for the destruction of your electric items.

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  2. James buggy

    I am using a huntington hi volt which is over powering Can you give me any advise to rectify this problem I thank you? It is military gen and done 1280 hrs James

    • Im not familiar with your generator, but mine used to overvolt even when idling. I adjusted a small screw which moved the throttle so it would idle much slower and this seemed to resolve the issue for me.