When you plug your EV in at home every night, you are probably not thinking about what is actually happening inside the car. You plug in a cable, the charge level goes up by morning, and that is it. But the physics of how electricity moves from the wall socket into your battery pack explains almost everything confusing about charging — why a highway DC charger fills your car in 30 minutes while your home socket takes all night, why some cars charge faster than others on the same charger, and why upgrading your home charger is one of the most practical improvements an Indian EV owner can make.
- All EV charging is either AC (alternating current) or DC (direct current). Your battery only stores DC, so AC charging requires a converter inside the car called the On-Board Charger (OBC). DC fast charging bypasses the OBC and delivers DC directly to the battery.
- The OBC is the ceiling for home and AC public charging. A car with a 3.3 kW OBC will charge at 3.3 kW from any AC source, even if the charger can supply more.
- India has five connector types in active use: 15A domestic socket, Bharat AC001, Type 2 (Mennekes), Bharat DC001, and CCS2. Knowing which your car supports tells you which public chargers are compatible.
- For most Indian 4W EV owners, a 7.2 kW home wallbox (₹20,000–35,000 installed) reduces a full charge from 14+ hours on a 15A socket to about 6 hours — practical overnight charging for most pack sizes.
What Is On-Board Charging?
Your EV's battery pack stores energy as direct current (DC) — electrons flowing in one direction at a fixed voltage. Your home socket, and every public AC charger, supplies alternating current (AC) — electrons oscillating back and forth at 50 cycles per second (50 Hz in India). Before AC electricity can be stored in the battery, it must be converted to DC.
That conversion happens inside the car, in a component called the On-Board Charger (OBC). The OBC is a high-power AC-to-DC converter — similar in principle to the brick that charges your laptop, but capable of handling kilowatts instead of watts. When you plug into any AC source, the electricity enters the OBC, which converts it to DC and delivers it to the battery pack at whatever voltage and current the Battery Management System (BMS) requests.
The OBC's power rating is the ceiling on how fast you can charge from any AC source. If your Tata Nexon EV has a 3.3 kW OBC and you plug it into a 22 kW public AC charger, you still charge at 3.3 kW — the charger is irrelevant beyond matching the connector. Upgrading to a car with a 7.2 kW OBC doubles your AC charging speed regardless of which charger you use.
DC Fast Charging: Bypassing the OBC
DC fast chargers do not use the car's OBC at all. Instead, they perform the AC-to-DC conversion inside the charger unit itself — using large, heavy, expensive power electronics that would never fit inside a car. The converted DC electricity is sent directly to the battery pack through a separate high-current DC connection in the charging connector.
This is why DC fast charging is so much faster: the charger's conversion hardware can be sized as large as needed (50 kW, 100 kW, 150 kW), without being limited by the compact OBC inside the car. The only constraint is what the car's battery can safely accept — which the BMS enforces in real time.
The Five Connector Types in India
India's EV charging landscape has five distinct connector types that an owner may encounter. Understanding which your car uses tells you immediately which public chargers are compatible — and which require an adapter or are simply unavailable to you.
| Connector | Current Type | Max Power | Who Uses It | Where You Find It |
|---|---|---|---|---|
| 15A domestic socket | AC | 2.3 kW | All EVs (via portable ICCB cable) | Home and offices |
| Bharat AC001 | AC | 7.2 kW | Most Indian 4W EVs | Home wallboxes, public AC bays |
| Type 2 (Mennekes) | AC | 22 kW | Premium imports: Ioniq 5, EV6, ZS EV, BYD | Premium networks, some malls |
| Bharat DC001 | DC | 50 kW | Older 4W EVs (pre-2022), many 3W EVs | Legacy highway fast chargers |
| CCS2 | DC | 150 kW+ | All new 4W EVs from 2022 onwards | New public fast charger installations |
15A domestic socket — Every Indian home has these. With the portable ICCB cable that ships with the car, you get 2.2–2.3 kW. Slow, but functional for daily top-ups.
Bharat AC001 — India's standardised AC charging connector defined under AIS-138 Part 1. Looks like a larger, rounded socket with an earth pin. Supports single-phase charging up to 7.2 kW. Found on almost all Indian-made EVs (Nexon, Tiago, Punch, Tigor) and on home wallbox chargers.
Type 2 (Mennekes) — The European AC standard, used by premium imported EVs. Supports three-phase charging up to 22 kW in theory; most Indian installations run single-phase, capping practical speed at 7.2–11 kW.
Bharat DC001 — India's original DC fast charging standard, a modified design combining elements of international DC connectors with Indian safety regulations. Mandatory for a period, so many highway chargers installed between 2018–2022 still carry these ports. Most new 4W EVs have now migrated away from it.
CCS2 (Combined Charging System Type 2) — The current Government of India mandated DC fast charging standard for four-wheelers, adopted through the AIS-138 Part 2 amendment. CCS2 uses the Type 2 AC socket with two additional large DC pins beneath it in a single combined connector — allowing both AC and DC charging through one port on the car.
If your car was purchased new in India after 2022, it almost certainly has a CCS2 port for DC fast charging and either Bharat AC001 or Type 2 for AC charging. If purchased before 2022, it may have Bharat DC001 (or no DC port at all). Check your owner's manual under "Charging Specifications" — it lists every port type the car supports.
How Long Does Charging Take?
Charging time depends on three numbers: battery capacity (kWh), charging power (kW), and current state of charge. The core formula is simple:
Approximate time to full = Pack size (kWh) ÷ Charging power (kW) × 1.15
The 1.15 factor accounts for charging efficiency losses — not all electrical energy from the wall reaches the battery; some is lost as heat in the OBC and wiring.
Check your car's spec sheet for "Battery Capacity" in kWh. Common examples: Tata Nexon EV (30.2 kWh standard, 40.5 kWh Max), Tata Tiago EV (19.2 kWh / 24 kWh), MG ZS EV (50.3 kWh), Mahindra XUV400 (39.4 kWh)
Home 15A socket = 2.2 kW. Bharat AC001 wallbox = check your OBC spec (3.3 or 7.2 kW). Public DC fast charger = 30–60 kW (depends on station and your car's acceptance rate)
Nexon EV Max (40.5 kWh) on 15A socket: 40.5 ÷ 2.2 × 1.15 ≈ 21 hours. Same car on 7.2 kW wallbox: 40.5 ÷ 7.2 × 1.15 ≈ 6.5 hours. On 50 kW DC charger to 80%: (40.5 × 0.8) ÷ 50 × 1.1 ≈ 43 minutes
Home Charging Upgrade: Is the Wallbox Worth It?
Most Indian EV buyers start with the 15A socket and the portable ICCB cable that came with the car. This is safe and works fine for modest daily distances. The math, however, favours an upgrade for anyone with a medium or large pack:
For a Nexon EV Max (40.5 kWh) that covers 50 km per day (using about 7–8 kWh), the 15A socket adds 2.2 kW × 8 hours = 17.6 kWh overnight — enough to replace daily usage, but without headroom. If you come home at 30% SOC, reaching 100% takes 14 hours. A 7.2 kW wallbox does the same top-up in about 4 hours.
Installation cost in India runs ₹20,000–35,000 for a 7.2 kW unit (wallbox hardware + dedicated 32A circuit from your meter board). The investment pays back quickly in convenience and flexibility for unplanned longer drives.
Do not use a multi-socket extension cord or a shared domestic circuit for EV charging. EV chargers draw their full rated current continuously for hours — the scenario most dangerous to undersized wiring. Use only a dedicated circuit with an appropriately rated MCB (32A for a 7.2 kW wallbox). Ask your electrician to inspect the supply cable from the meter board, not just install the wallbox unit.
What to Expect at a Public DC Fast Charger
When you arrive at a highway DC charger and plug in, charging power does not immediately jump to the station's rated maximum. The BMS controls a charging curve:
- 0–15% SOC: Power may be limited to protect cells at very low voltage
- 15–80% SOC: Full charging power available — this is where the advertised speed applies
- 80–100% SOC: Power tapers sharply to protect cells from overcharge — the last 20% can take nearly as long as the first 60%
This is why the standard advice is to target 80% on a DC charger and continue driving. You get the fast part of the curve and avoid the slow taper.
India's public DC charging networks (Tata Power EZ Charge, ChargeGrid, Ather Grid, EESL, Statiq) charge either per kWh (₹12–22/kWh) or per minute. Per-kWh billing gives better value when the charger and car match well in power. Per-minute billing becomes expensive if you stay connected past 80% SOC while the charge rate tapers. Check the billing mode before starting a session and unplug once you reach your target SOC.
Key Takeaways
- All EV batteries store DC. AC charging uses an On-Board Charger inside the car. DC fast charging skips the OBC and delivers high-power DC directly — which is why it charges 10–20× faster.
- Your OBC's power rating limits your AC charging speed from any source. The 3.3 kW OBC in many budget Indian EVs is the most common bottleneck — no wallbox upgrade can exceed it.
- India uses five connector types. Post-2022 cars use CCS2 (DC) and Bharat AC001 or Type 2 (AC). Pre-2022 cars may use Bharat DC001. Check your owner's manual to confirm compatibility before planning any public charging stop.
- A 7.2 kW Bharat AC001 wallbox (₹20,000–35,000 installed) reduces overnight charging time by 3–4× compared to the 15A socket. For packs above 30 kWh, this is a worthwhile upgrade.
- DC public chargers run at full speed between 15–80% SOC. Charging to 80% and driving maximises time efficiency on highway stops.