kW, kWh, 7.4 kW, 150 kW — EV charging specs can be bewildering. This guide translates the numbers into real-world charging times and helps you understand exactly what speed of charger you need at home.
Before diving into speeds, it is worth fixing one persistent source of confusion: kW and kWh are different things.
Your home wallbox has a power rating in kW. Your car has a battery capacity in kWh. Charging time is simply battery capacity divided by power — with some real-world losses factored in.
Example: A Volkswagen ID.4 with a 77 kWh usable battery, charged on a 7.4 kW wallbox from 20% (15.4 kWh remaining) to 80% (61.6 kWh) needs to add 46.2 kWh. At 7.4 kW: 46.2 ÷ 7.4 = 6.2 hours. A comfortable overnight charge.
Irish EV drivers encounter a range of charging speeds:
The vast majority of SEAI-approved home charger installations in Ireland are 7.4 kW (32A, single-phase). This is not arbitrary it reflects the limits of Ireland’s standard residential electricity supply:
At 7.4 kW, a typical Irish commuter driving 40 km per day needs roughly 1.5–2 hours of charging to replace their daily driving. An overnight session of 8–10 hours can replenish 55–70 kWh — enough for 300–400 km of range on most popular EVs. For Irish driving patterns, this is more than sufficient.
These figures assume a charge from 20% to 80% (the recommended daily range) and account for on-board charger (OBC) limits and typical efficiency losses (~10%):
All of these fit comfortably within an overnight charging window. The 7.4 kW wallbox is adequate for every vehicle in this table.
One thing that confuses many buyers: the car’s on-board charger (OBC) caps charging speed regardless of how powerful your wallbox is.
The OBC is the component inside the car that converts AC power to DC for the battery. If your car has a 7.4 kW OBC, installing an 11 kW or 22 kW wallbox will not make it charge faster — the car will still draw only 7.4 kW.
OBC ratings for popular Irish EVs:
Check your car’s specification sheet or the manufacturer’s website for your exact OBC rating before choosing a wallbox power level.
For home AC charging, the answer is effectively no. The power levels involved (3.7–7.4 kW) are so gentle relative to battery capacity that thermal stress is minimal. Battery degradation from home charging is negligible over a typical vehicle lifetime.
DC rapid charging at very high rates (100 kW+) does generate more battery heat and can contribute to slightly faster degradation if used as the primary charging method. Most manufacturers are explicit that occasional rapid charging is fine — it is daily dependence on rapid chargers that causes concern.
The practical takeaway: charge at home on AC every night, and use rapid DC chargers freely when you need them on longer journeys.
Modern OCPP-enabled chargers like the Easee One, MyEnergi Zappi, Ohme Home Pro, and Wallbox Pulsar Plus allow you to control charging speed remotely or via scheduling:
If your property has three-phase supply — check with ESB Networks using your MPRN if unsure — you can install an 11 kW or 22 kW wallbox and take advantage of your car’s higher OBC rating.
At 11 kW, a Hyundai Ioniq 6 (53 kWh) charges from 20% to 80% in around 3 hours. At 22 kW, a Renault Zoe (52 kWh) does the same in under 1.5 hours. For households that drive high mileages or have multiple EVs, three-phase supply is genuinely valuable.
Note: chargers above 7 kW require notification to ESB Networks before installation. Your installer handles this, but it can add 2–4 weeks to the process.
For 95% of Irish homeowners with a single EV and standard single-phase supply:
The right charging speed at home is not the fastest possible — it is the one that reliably fills your battery overnight at the lowest cost per kWh.
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Approximately 30–40 km per hour, depending on your EV’s efficiency. A typical EV consumes around 18–22 kWh per 100 km, so a 7.4 kW charger adds roughly 33–40 km of range per hour of charging.
As an emergency backup, yes. For daily charging, no — a 3-pin socket delivers only 1.9–2.3 kW, takes 20+ hours to fully charge most EVs, and risks overheating on standard household socket circuits not rated for sustained high loads. Always install a dedicated wallbox for regular home charging.
Yes — if you later move to a car with a higher OBC or switch to three-phase supply, you can replace the wallbox unit. The circuit and consumer unit work is the bigger cost; the wallbox itself is relatively straightforward to swap out. Ask your installer to run conduit that could accommodate a future three-phase circuit.
The most common reason is the car’s OBC limit — if your car has a 6.6 kW OBC and your wallbox is 7.4 kW, the car draws only 6.6 kW. Other causes include hot or cold battery temperatures (the BMS reduces charge rate to protect cells), and the car’s CC/CV absorption phase above 80% state of charge.
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— safeelectric.ie
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