Used or new generator: what to check before buying in Kinshasa

Before buying a used generator, check five things: the hour meter, the engine and alternator plates against the seller's description, a cold start, a run under real load with stable voltage and a frequency close to 50 Hz, and the colour of the exhaust smoke. A new set has a published datasheet, so you can compare it line by line instead of guessing.

New or used? Choose new when the set powers a critical load (a clinic, a cold room, servers) or when you want a certain identity and datasheet. Used can make sense if you can check the plates and the service history, then run a load test of at least 30 minutes. For a need of a few weeks, rental avoids both.

What should you check on the plates and paperwork?

Start with the rating plates. The engine and the alternator each carry one, with a model and a serial number. The models must match the seller's description.

Note down or ask for at least:

• the engine model and serial number;
• the alternator model, its kVA rating, voltage and frequency;
• the controller model;
• the hours shown on the hour meter or on the controller;
• the invoices, the service log and the dates of the last oil changes.

Note: the kVA on the alternator plate can be higher than the set's rating. The engine limits the set's output, so check the exact engine model above all.

Why does the exact model matter so much? Because two sets can look the same and still have different outputs. Here are two sets from our range, taken from their datasheets:

Same 3-cylinder block, same displacement, same dimensions: by eye, nothing tells them apart. On the plates, only the engine suffix (TG1 or TG2) and the last letter of the alternator model (F or H) separate the 45 kVA set from the 60 kVA set. So "60 kVA" in an advert is not enough: ask for a sharp photo of each plate.

Read the hour meter with care. A meter may have been replaced. Compare the hours shown with the service log and with the overall condition of the engine.

How do you run a cold start and a load test?

Ask the seller not to start the set before you arrive. A warm engine starts more easily and can hide a fault. Put your hand on the engine block: it should be cold.

During the cold start, watch for:

• cranking time: the engine should fire without a long crank;
• smoke in the first seconds, then again after a few minutes;
• noises: knocking, ticking, whistling, unusual vibration;
• any alarm on the controller.

Then run the set under a real load: a no-load run proves almost nothing. Connect real appliances or, better, a resistive load bank if you can get one. A load bank should be connected, and any measurement at the terminals taken, by a qualified electrician, with the set stopped while connecting. Step up towards the load you will actually use, staying below the prime rating. Our guide to prime and standby power explains why the standby figure is not your reference.

Under load, check these readings on the controller:

• voltage: it should match the alternator plate (on our three-phase Perkins-engine sets, 400/230 V or 380/220 V depending on the setting) and stay steady;
• frequency: close to 50 Hz, the grid frequency in the DRC;
• temperature and oil pressure, with no alarm.

As a general rule, frequency dips briefly when you add load, then recovers towards 50 Hz. A value that stays low or keeps swinging is a bad sign. Let the set run for at least half an hour so the engine reaches operating temperature.

What are the warning signs?

Some signs are reason enough to walk away, or to have a technician inspect the set before you pay.

• Smoke. Persistent black smoke under load usually points to a lack of air (clogged air filter), excess fuel (injection) or overload. Blue smoke points to burning oil. White smoke that does not clear once the engine is warm can come from unburnt fuel or coolant. Our guide to a generator that won't start or blows black smoke covers these causes.
• Leaks. Oil, fuel or coolant under the set, around seals or hoses.
• Overheating. Temperature that keeps rising, a temperature alarm, a clogged fan or radiator.
• Unstable voltage. Lights that flicker, voltage or frequency that swings under a steady load.
• Inconsistent paperwork. Missing or unreadable plates, a model that differs from the advert, no service history.

One sign alone does not always rule a set out. It does need an explanation, and you should factor it in before buying.

Buying new: how do you compare datasheets?

A new set has a full datasheet. You do not have to piece together what it is from the plates. Every generator page on our site links to its PDF datasheet, and our catalogues are grouped on the catalogues and datasheets page.

Compare the same lines across offers: prime power, engine, alternator, controller, soundproof or open-frame version, tank and fuel consumption. Our guide on how to read a generator datasheet explains every line and includes a quote checklist.

Is your need temporary, for a construction site or an event? Generator rental may make more sense than buying.

After the purchase: what first service should you plan?

Whether the set is new or used, start a service log on day one. Record the hour-meter reading on the day you buy it.

For a used set with an incomplete history, a full service by a technician is a sound starting point: oil and filters, coolant, belts, battery and a load test. For a new set, follow the intervals in the engine manual. Our generator maintenance guide sets out the schedule.

We provide preventive and corrective maintenance and supplies spare parts for the equipment we sell. Send us the brand, model and serial number from the plates.

For a quote on a new set, message us on WhatsApp at +243 903 005 060 with the output or model you need. Prices are given on request. You can also use our contact page or visit our showroom on Avenue des Huileries in Gombe.

Frequently asked questions

How many hours can a used generator have?

There is no single threshold. Service life depends on the engine, how the set has been used and, above all, how it has been maintained. A set with many hours and a complete service log can be a safer buy than a lightly used set that was never serviced.

How can I check the frequency without special equipment?

On most diesel sets fitted with a controller, frequency is shown on the display. Our Perkins-engine sets use a Deep Sea controller. Otherwise, an electrician can measure it with a multimeter that has a Hz function and a safety category rated for 400 V. Under load, the frequency should stay close to 50 Hz.

Is a set that starts easily with no load in good condition?

Not necessarily. A no-load start shows neither how the voltage holds, nor the smoke under load, nor how the temperature rises. Only a run under real load, for at least half an hour, gives a reliable picture.

Which documents should I ask the seller for?

Ask for the original invoice or proof of purchase, the service log and parts invoices. Ask for sharp photos of the engine and alternator plates too. The engine model, in particular, must match the advert.

Sources: MK Energies & Services generator datasheets (Perkins engines, Leroy-Somer alternators, Deep Sea controllers).