Devices after dark: why your tech charging sometimes makes sense to do off peak

Home technology doesn't use anywhere near as much energy as a dryer or a heat pump. A full phone charge costs less than a cent. But most homes have a lot of it, plenty of it is always on, and more and more of it runs on batteries that can be topped up whenever suits.

This guide looks at which devices matter, which ones can move into off-peak hours, and how to charge them safely while you do.

Night Saver offers lower rates from 9pm to 7am compared to day rates on the same plan. Any savings depend on your usage and how much of it you shift into those hours. Ts&Cs and eligibility criteria apply.

Screens and devices vary a lot by model, size and settings, so treat these as ballpark figures. What stands out is how big the gap is between the smallest and largest items.

These figures are indicative estimates, not a bill guarantee. Costs use the national average residential price of 42.1c per kWh from MBIE's Quarterly Survey of Domestic Electricity Prices (15 August 2026), rounded to 42c. Your own rate will depend on your plan, network and region, and actual energy use varies by model, settings and how you use it.

The standby story

Devices left switched on or in standby can collectively add up to $200 to a yearly power bill, according to EECA.

Consumer NZ testing found phone, tablet and laptop chargers left plugged in drew very little, under 0.5 W in its tests. Some TVs, games consoles and microwaves used between 2 and 5 W on standby, and some printers used far more. Smart devices that stay connected to Wi-Fi tend to draw more than simpler ones.

Home tech falls into two fairly clear groups.

The pattern is simple. If something runs on a battery, the charging can usually happen at a different time to the using. If it plugs in and you use it live, it runs when you're using it.

Night owls are already there

If most of your screen time happens after 9pm, it's already inside Night Saver's lower-rate hours. The late movie or the evening gaming session doesn't need to change.

Start with the biggest batteries

The bigger the battery, the more a lower rate is worth. An e-bike charge uses around 30 times the energy of a phone charge. Laptops, cordless vacuums and power tool batteries come next. Phones barely register, so the main reason to think about them is safety, not cost.

Robot vacuums

A robot vacuum runs on its battery while it cleans, then draws power from the dock to recharge. If you schedule its run to finish around 9pm, most of the recharging lands in the lower-rate hours. Keep the dock on a hard, clear surface and follow the manufacturer's guidance on where it sits.

Cordless stick vacuums

Most of these live on their wall charger full time. Plugging the charger into a smart plug set to run from 9pm to midnight tops the battery up in the lower-rate hours, and it means the vacuum isn't left charging indefinitely.

Laptops and tablets

Charge them in the evening while you're winding down, on a hard, flat surface rather than a bed or couch. Many laptops have battery care settings that stop charging at around 80%, which is easier on the battery over time.

Phones

The energy is tiny, so timing makes little difference to your bill. Many phones have optimised or adaptive charging that slows things down overnight. If you charge beside the bed, put the phone on the bedside table rather than on the bed or under a pillow.

E-bikes and e-scooters

These are the biggest batteries most homes have after an EV. Charge them after 9pm while you're home and awake, using the charger supplied, on a hard surface and away from exits. Unplug once the battery is full rather than leaving it charging overnight.

Updates, backups and downloads

Computers and consoles can often schedule big downloads and backups for overnight. Keep in mind that a console left in rest mode to do this uses more power than one that's switched off, so it's a trade-off rather than a free win.

EECA notes that smart plugs and smart devices can help you make the most of off-peak power and avoid wasting energy on appliances you aren't using. A few tips for using them well:

• Buy from reputable suppliers and check the plug is rated for the device you're connecting.

• Set chargers to switch on at 9pm and off again a few hours later, so batteries fill in the lower-rate hours and don't sit on charge all night.

• Use schedules to switch off the TV, console and printer overnight when nobody's using them.

• Avoid daisy-chaining smart plugs or plugging them into crowded multiboxes.

Charging safely

Off-peak charging is about when you charge, not charging for longer or leaving devices unattended. Fire and Emergency New Zealand recommends:

• Using chargers and cords that aren't damaged, modified or meant for a different device

• Charging on a hard, flat surface

• Not using or charging lithium battery devices that have been dropped or damaged

• Disconnecting devices from the charger once they're fully charged

• Storing battery devices somewhere cool and dry, out of direct sunlight

• Keeping cords uncoiled and out from under carpet or bedding

If a device starts to smoke or give off fumes, Fire and Emergency advises getting out straight away and calling 111. Make sure you have working smoke alarms in your home.

Because rates differ between plans and regions, the most useful number is the gap between your day rate and your night rate. Your bill or plan details will show both. The table below shows what every 10c per kWh of difference is worth over a year. If your gap is 15c, multiply by one and a half. If it's 20c, double it.

On its own, moving home tech charging won't change your bill much, and it's worth being upfront about that. It earns its place as part of a wider routine alongside laundry, dishes, hot water and EV charging. Cutting standby is often the bigger win.

Charge points

• Phones cost cents a year to charge. E-bikes and laptops are worth more attention.
• Always-on and standby devices can add up to more than the devices you actively use.
• Smart plugs can shift charging and switch off standby in one go.
• Charge on hard surfaces, unplug when full, and don't leave big batteries charging while you sleep.

Night Saver offers lower rates from 9pm to 7am every night, compared to day rates on the plan. It's an open-term plan and needs a communicating smart meter. It tends to suit night owls, households that can move energy-heavy tasks to after 9pm, and anyone charging an EV overnight. If most of your power use happens during the day and can't move, another plan may suit you better, and you can compare our plans side by side.

Other useful resources

• EECA: Easy ways to save on your energy bills

• EECA: Choose good appliances

• Consumer NZ: How much power do your appliances use?

• Fire and Emergency NZ: Batteries and electronics

• Take Charge - Saving Power In The Kitchen

This guide is general information only. It isn't electrical, plumbing, fire safety, food safety or financial advice, and nothing in it should be relied on as a guarantee of safety or of any particular saving.

Always follow the manufacturer's instructions and safety warnings for your appliances and devices, and use a registered electrician or licensed plumber for any electrical or plumbing work. If you're unsure whether something is safe to run while you're asleep or away from home, don't.

Never charge a device that is damaged, swollen, hot to the touch or behaving unusually. Only use chargers supplied or approved by the device manufacturer, and check that any smart plug or timer is suitable for the device it controls.

Energy use and cost figures are indicative estimates based on typical appliances and the national average residential price of 42.1c per kWh (MBIE Quarterly Survey of Domestic Electricity Prices, 15 August 2026). Your actual costs, and any savings, will depend on your plan, rates, network, meter, appliances and how you use them.

Night Saver offers lower rates from 9pm to 7am compared to day rates on the same plan. Anticipated savings are based on those lower rates, and actual savings vary based on usage. Night Saver requires a communicating smart meter. Ts&Cs and eligibility criteria apply to all Meridian plans and offers.

To the extent permitted by law, Meridian Energy isn't liable for any loss, damage or injury arising from reliance on the information in this guide.

Sources

• EECA, Easy ways to save on your energy bills: standby devices can add up to $200 a year; smart plugs and off-peak use. https://www.eeca.govt.nz/for-homes/save-on-your-energy-bills/easy-ways-to-save-on-your-energy-bills/ 

• Consumer NZ, How much power do your appliances use?: charger and standby power testing. https://www.consumer.org.nz/home-and-living/home-energy/appliance-running-costs 

• Fire and Emergency New Zealand, Batteries and electronics: safe charging guidance. https://www.fireandemergency.nz/home-fire-safety/home-fire-hazards/batteries-and-electronics/ 

• MBIE, Quarterly Survey of Domestic Electricity Prices, 15 August 2026: national average 42.1c/kWh. https://www.mbie.govt.nz/building-and-energy/energy-and-natural-resources/energy-statistics-and-modelling/energy-statistics/energy-prices/electricity-cost-and-price-monitoring 

• Device draw figures are typical estimates for common models and will vary by brand, size and settings.