Green Cell Habu 11kW: 3-phase EV charging test before purchase

During a test drive, the battery is discharging — the OBC (onboard charger) isn't working at all. Charging problems only appear after connecting to an EVSE.

A test with a 3-phase 11kW charger (Green Cell Habu) forces maximum load on the AC path. It's like a stress test for the onboard charger — if something is wrong, we'll see it on the current curve within a dozen or so minutes.

For an EV buyer, this is one of the cheapest ways to avoid spending 3000–8000 PLN on an OBC replacement after purchase.

The most common signals: the car doesn't start a charging session, stops after a few minutes, charges on one phase instead of three, or draws significantly less current than the manufacturer declares.

Note: reduced charging current at very low or very high battery temperatures is normal BMS (Battery Management System) behavior. Similarly, the first and last 10% SOC charge slower — that's not a fault, just cell physics.

The problem starts when the car, at a temperature of 15–35°C and SOC 20–80%, doesn't reach its declared AC charging power. That's when we have a reason to test.

The OBC is an AC/DC converter installed in the car. It converts alternating current from the grid into direct current to charge the battery. In the 3-phase 11kW version, it consists of three independent rectifier paths.

Degradation of one path (e.g., a damaged MOSFET transistor, a burnt capacitor, connector corrosion after flooding) causes a power drop of 1/3 or a complete loss of one phase. In a single-phase 2.3kW test, this defect may be invisible — the car "charges", but at a fraction of the power.

That's why a test with an 11kW charger is crucial: it forces simultaneous operation of all three AC paths and reveals current asymmetry, thermal instabilities, and communication errors that remain hidden under low load.

A healthy OBC at SOC 20–80% and temperature 15–35°C should maintain power close to the declared value (e.g., 11kW ±10%) throughout the test. Current on the three phases should be symmetrical with a deviation of up to ~0.5A.

Warning signals: power drops below 70% of declared without thermal reason, current on one phase is zero or significantly lower, the session interrupts and resumes cyclically, the car "renegotiates" power every few minutes.

Trap: a seller may claim the car "has an 11kW OBC", but in reality, a specific market version has a 7.4kW OBC (e.g., some Hyundai Kona, basic VW ID.3 trims). We check this in the VIN specification, not on word.

If a single-phase test from a 230V outlet looked "fine", but a three-phase test reveals problems — that's exactly why we do a full-load test. The analogy from the article about PHEV charging test applies doubly here: a single-phase test is not enough.

Stable result (power ±10% of declared, phase symmetry, no interruptions) — this is a strong argument for purchase. The OBC is functional, and the cost of potential charging problems is eliminated.

Result with deviations (power 70–90%, slight asymmetry, occasional fluctuations) — negotiate the price. The car drives and charges, but the OBC shows early signs of degradation. OBC replacement costs 3000–8000 PLN depending on the brand.

Bad result (one phase missing, session interruptions, power below 60%) — walk away or commission deep diagnostics. A full HV battery and inverter diagnostics will show whether the problem is limited to the OBC or goes deeper — to the BMS, contactors, or the traction battery itself.

The charging test is one element of a full EV/PHEV audit. If you're interested in a broader picture of the car's condition, also check the difference between battery SOH and SOC — because "100% charge" doesn't mean a healthy battery.

The NRGkick article describes a single-phase PHEV test and focuses on recuperation. This post is an extension to full 3-phase load, which makes sense primarily for BEVs with 11kW+ OBC.