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In slow traffic, the EV's heater uses energy by the hour

Cabin cooling, heating and demisting affect range differently from driving. A time-based example explains winter traffic without sacrificing visibility.

By BijuliMotor5 min read

A car moves five kilometres in an hour of traffic. Its cabin system has still been running for an hour. That is why a journey can look unusually inefficient in kWh per 100 km even when the driver has barely used the accelerator.

This is relevant in Kathmandu queues and on a cold, wet trip outside the Valley. Cabin comfort takes energy, and clear glass is a safety requirement. The answer is to understand the load and plan the journey, not to turn off demisting while the windscreen fogs.

Distance does not explain every load

The motor's energy use is closely connected to movement, speed and gradient. A heater, compressor, fan and other accessories also consume energy over time. The consumption display may combine those loads into a distance-based figure.

Assume an illustrative cabin load averaging 1 kW for two hours. It uses 2 kWh. Over 100 km that adds 2 kWh per 100 km. Over 20 km it adds 10 kWh per 100 km, even though the accessory used the same energy in both cases.

If the average load is 2 kW instead, the energy doubles to 4 kWh. These are examples, not measurements of a named EV's heating or cooling. Actual systems vary with temperature, settings, insulation and control strategy.

The calculation helps explain a jump in consumption during a very slow journey. It does not show that the battery has permanently lost capacity. Compare similar conditions before drawing that conclusion.

Heating and cooling are not identical jobs

Different EVs use different cabin-heating arrangements. Some rely on resistive heating; some have a heat pump or another integrated system. Confirm the equipment on the Nepal variant rather than assuming it comes with a feature listed overseas.

A heat pump moves heat and can reduce electricity use in suitable conditions, but performance depends on the design and temperature. A brochure label alone cannot predict your winter range penalty. Ask about the operating limits and what the car does in colder conditions.

Air conditioning can also remove moisture from cabin air. A defogging function may use it alongside heating and fresh-air intake. Kia's EV3 owner's manual describes that interaction for its system. It is a technical example, not a control sequence to copy into a different Nepal car.

Use the buttons and instructions in your own manual. If visibility deteriorates, clear the glass before continuing. A few saved units of electricity do not justify driving with a fogged windscreen.

The battery may need temperature control too

Cabin and battery thermal systems are related in some designs but serve different jobs. Cooling the battery after demanding use can consume energy even when the passenger does not request a cold cabin. A fan or compressor running is not automatically a fault.

The Punch EV manual hosted by Sipradi explains that heating and cooling use battery energy. Its range advice includes reducing prolonged heater and air-conditioner use. Read the model's complete guidance, including warnings. The same setting does not produce the same result in every vehicle.

Preconditioning, where available, may help prepare the car while connected to a suitable supply. Confirm how the system works, whether it uses external energy and which connected functions are supported locally. An app's remote-cooling icon does not prove battery preconditioning is included.

A useful winter comparison starts with the route

Suppose you normally use 30 kWh for a journey and expect a longer traffic delay in cold rain. Add a justified accessory allowance and reserve rather than applying a universal “winter reduces range by 30%” rule. The car, weather and duration determine the result.

For a 40 kWh usable battery, an extra 3 kWh represents 7.5 percentage points of its usable capacity. On a large pack that same load is a smaller percentage. This is one reason a fixed percentage claim can mislead across vehicles.

Track journey time, distance, weather, cabin settings and arrival charge. Several records under comparable conditions can help refine the estimate. One difficult drive does not establish a model's permanent consumption or a battery warranty fault.

Maintain airflow and visibility

Check wipers, washer fluid and cabin-filter service. A dirty filter or an obstructed intake can reduce useful airflow. Have persistent poor demisting or abnormal cabin operation assessed rather than repeatedly selecting colder or hotter settings and hoping it clears.

Keep wet items from adding unnecessary moisture where practical, and use the specified fresh-air or defog arrangement. Continuous recirculation may not be the correct response to fogging. The manual's visibility instructions take priority over a range-saving tip.

Never leave a child or vulnerable person unattended in a parked vehicle on the assumption that remote air conditioning will continue. A connected feature can stop, fail or lose communication.

Plan the charging stop around time as well

If waiting in a road queue changes arrival energy, revise the next charging decision. A charger that looked optional before a long delay may now be useful. Check compatibility and operation before committing to a low reserve.

Record the arrival charge and how long the delayed journey took. Those figures can help plan a similar winter trip. Keep the windscreen clear throughout; if the remaining energy becomes too low, change the charging plan rather than sacrificing visibility.

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