Table of Contents
The Fundamental Difference You Need to Know
Your phone charger does one thing: it converts the AC power from your wall socket into DC power that your phone battery can store. The charger is the small brick between the wall and your phone.
EV charging works the same way — except there are two completely different places the conversion can happen.
Option A: The conversion happens inside the car. The wall supplies AC power, the car's onboard charger converts it to DC, and it flows into the battery. This is how all home charging works, and it is limited by the size of the onboard charger — which is a physical box inside the car.
Option B: The conversion happens at the charging station. A large, powerful charger inside the station converts AC grid power to DC, and pushes that DC directly into the battery — bypassing the onboard charger entirely. This is DC fast charging, and it is why it is so much faster.
Everything else about EV charging — the different power levels, the different connectors, the speed differences — flows from this one distinction.
[IMAGE_SEARCH] keyword: EV onboard charger vs DC fast charger diagram AC DC context: Diagram showing the difference between AC charging (converter inside car) and DC fast charging (converter in station) placement: after the explanation of onboard vs external charger [/IMAGE_SEARCH]
Type 1 — Charging From a Regular Wall Socket
The slowest option, and the most universally available: plug your EV into any standard 5-amp or 15-amp household socket using a cable that comes with the car.
In India, a standard socket supplies roughly 2.2 kW of power. A typical EV with a 30 kWh battery would take 14–16 hours to charge from empty to full this way. For most people, this means plugging in overnight and waking up to a full car — which works perfectly well if your daily driving is under 100–120 km.
The limitation is not the socket. It is the safety of running a high-power device for 14 hours continuously on a household circuit that was not designed for it. Most EV manufacturers recommend this only as a backup option, not a daily routine.
Best for: Top-up charging when nothing else is available. Emergency charging on a road trip when you find a friendly homeowner.
Type 2 — Home Charging With a Wallbox
A wallbox (also called a home charging unit or EVSE) is a dedicated charging device installed at your home by an electrician. It connects to a dedicated circuit with a higher power rating than a standard socket.
In India, typical home wallboxes supply 3.3 kW or 7.4 kW. At 7.4 kW, a 30 kWh battery charges from empty in about 4–5 hours — meaning you plug in after dinner and have a full car by midnight.
The wallbox itself does not charge the battery. It supplies power safely and communicates with the car — telling it how much power is available. The actual conversion from AC to DC still happens inside the car, in the onboard charger. This is why two different EVs plugged into the same wallbox might charge at different speeds — their onboard chargers have different power ratings.
[IMAGE_SEARCH] keyword: home EV wallbox charger installed garage context: A home wallbox charger installed on a wall, showing the compact unit and charging cable placement: after explaining what a wallbox is [/IMAGE_SEARCH]
Best for: Daily charging. This is how the majority of EV owners charge the majority of the time.
Type 3 — AC Fast Charging at Public Stations
Public AC charging stations work exactly like a home wallbox — they supply AC power which the car's onboard charger converts to DC — but they can supply more power. Typically 11 kW or 22 kW, compared to 7.4 kW at home.
The catch: your car can only use as much power as its onboard charger can handle. If your car has a 7.4 kW onboard charger, connecting it to a 22 kW public AC charger gives you... 7.4 kW. The extra capacity at the station is wasted. Only cars with 11 kW or 22 kW onboard chargers can take full advantage.
This is why two different EVs at the same public charger charge at completely different speeds — and why the station's advertised speed and the actual charging speed are sometimes very different numbers.
Best for: Topping up during a shopping trip, office parking, or any situation where the car sits for 1–3 hours and you want to add meaningful range.
Type 4 — DC Fast Charging and Rapid Charging
This is where EV charging becomes genuinely impressive — and where it is completely different from anything that happens with your phone.
DC fast chargers bypass the car's onboard charger entirely. The charging station itself contains the conversion equipment — large, expensive, powerful — and sends DC power directly into the battery at very high rates. Typical power levels in India today are 30–60 kW, with newer stations reaching 120–240 kW. Some international stations reach 350 kW.
At 60 kW, a 30 kWh battery goes from 20% to 80% in about 25–30 minutes. That is the range of a full working day of driving added in the time it takes to get a coffee.
[IMAGE_SEARCH] keyword: DC fast charging station electric vehicle highway context: A DC fast charging station at a highway stop, showing the large charging unit and cable connecting to an EV placement: after explaining what DC fast charging is [/IMAGE_SEARCH]
The limitation: not all EVs support DC fast charging. Budget EVs and some older models only have AC charging capability. And among those that do support DC fast charging, each car has a maximum DC charging rate — a 30 kW car connected to a 120 kW charger will only draw 30 kW.
Best for: Long-distance travel. Highway charging stops. Anywhere you need significant range added quickly.
The Connector Chaos — Why So Many Different Plugs
This is the part that confuses almost everyone — and for good reason. There is no single universal EV charging plug. Different manufacturers, different regions, and different charging speeds use different connectors.
In India, the standards landscape is consolidating, but you will still encounter:
Connector | Used for | Common in India |
|---|---|---|
Type 2 (Mennekes) | AC charging up to 22 kW | Most new EVs |
CCS2 (Combined Charging System) | DC fast charging | Tata, MG, Hyundai, most new EVs |
CHAdeMO | DC fast charging | Older Nissan, some Japanese EVs |
GB/T | AC and DC | Chinese EVs (BYD, some others) |
Bharat AC-001 | AC slow charging | Indian standard, older infrastructure |
Bharat DC-001 | DC fast charging | Indian standard, older infrastructure |
The good news: most modern EVs sold in India after 2022 use CCS2 for DC fast charging and Type 2 for AC charging. The older Bharat standards are still present in older public infrastructure but new installations are moving to CCS2.
Many charging stations have multiple connector types available at the same station — you just pick the cable that fits your car.
[IMAGE_SEARCH] keyword: EV charging connector types CCS2 Type 2 CHAdeMO comparison context: Showing the different EV charging connector types side by side for comparison placement: after the connector table [/IMAGE_SEARCH]
Why Charging Slows Down Near 100%
You have almost certainly noticed this: charging is fast when the battery is low, and gets progressively slower as it approaches 100%. This is not a quirk or a bug. It is a fundamental property of how lithium-ion batteries accept charge.
Lithium-ion batteries charge in two phases:
Phase 1 — Constant Current (CC): The charger pushes a steady, high current into the battery. This is the fast part. The battery accepts this willingly from roughly 0% to 80% SOC. This is where most of your range is added.
Phase 2 — Constant Voltage (CV): As the battery approaches its maximum voltage limit, the charger holds the voltage steady and lets the current taper off naturally. This is slow. Pushing full current into a nearly-full battery would overvoltage the cells and damage them.
The transition from Phase 1 to Phase 2 happens at different SOC levels depending on the car and chemistry, but 80% is a common point where the speed starts dropping noticeably. Charging from 80% to 100% takes roughly the same time as charging from 20% to 80% — for much less range added.
This is why every EV recommendation for long trips is: charge to 80%, drive, charge to 80% again. Chasing 100% wastes disproportionate time.
Why Cold Weather Makes Charging Slower
A cold battery resists fast charging. This is electrochemistry, not a software choice.
At low temperatures, the lithium ions inside the battery move more slowly through the electrolyte. Pushing them in too fast — at the same rate as a warm battery — causes metallic lithium to deposit on the electrode surface rather than being properly absorbed. This is called lithium plating, and it permanently damages the cell.
The BMS (the battery's management computer) knows this. It monitors battery temperature and automatically limits charging speed in cold conditions — sometimes to as little as 10–15% of the maximum rate on a very cold battery.
This is why DC fast charging on a cold battery starts slowly and speeds up as the pack warms through the charging process. Some newer EVs — Hyundai IONIQ 5, Kia EV6, several BYD models — actively pre-heat the battery before a fast charge session if you tell the navigation system you are heading to a charger. This is called battery preconditioning, and it makes a significant difference.
What the Numbers Actually Mean — kW and kWh Explained
Two numbers appear everywhere in EV charging discussions and they are constantly confused:
kWh (kilowatt-hours) — This is the size of the battery. How much energy it stores. A 30 kWh battery stores 30 kilowatt-hours of energy. Think of it as the size of the fuel tank.
kW (kilowatts) — This is the speed of charging. How fast energy is going into the battery. A 7.4 kW charger adds 7.4 kilowatt-hours every hour. Think of it as how fast the fuel pump fills the tank.
So: Time to charge = Battery size (kWh) ÷ Charger speed (kW)
A 40 kWh battery on a 7.4 kW charger: 40 ÷ 7.4 = 5.4 hours from empty to full.
The same 40 kWh battery on a 50 kW DC fast charger: 40 ÷ 50 = 0.8 hours — about 48 minutes. (In practice slightly longer because of the CV phase tapering, but close.)
These two numbers — the battery size and the charger speed — are the only things you need to estimate any charging time.
Key Takeaways
There are two fundamentally different types of EV charging: AC (where the converter is inside the car) and DC (where the converter is in the station). DC fast charging is faster because it bypasses the car's onboard charger.
Home charging with a wallbox covers 90% of daily needs for most drivers. DC fast charging is for long-distance travel.
Charging slows near 100% because of the constant-voltage phase — this is chemistry, not a malfunction. Stop at 80% on long trips.
Cold weather slows charging because the BMS limits current to prevent lithium plating. This is protecting your battery, not throttling your experience.
kWh is battery size. kW is charging speed. Divide one by the other to get charging time.
References
IEC 61851-1:2017. Electric Vehicle Conductive Charging System — Part 1: General Requirements.
Bureau of Energy Efficiency, India. (2022). Charging Infrastructure for Electric Vehicles — Guidelines and Standards.
SAE International. (2017). SAE J1772: Electric Vehicle and Plug-in Hybrid Electric Vehicle Conductive Charge Coupler.
Tomaszewska, A. et al. (2019). Lithium-Ion Battery Fast Charging: A Review. eTransportation, 1. https://doi.org/10.1016/j.etran.2019.100011
This is the Basic level of the EVPulse Charging series.
→ Next: How Charging Actually Works Inside Your EV — Intermediate — the onboard charger, CC-CV charging protocol, and what the BMS is doing every second you are plugged in.
Published on EVPulse — the most technically rigorous source for battery technology and EV engineering coverage.