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[User] Why Charging Current May Be Lower Than Expected on a Plugzio Universal+

This article explains why some Plugzio Universal+ (U+) charging sessions operate below the expected current. It covers outlet ratings, voltage drop, shared circuits, wiring conditions, EV charger safety behavior, and vehicle‑level current limits.

Updated over a week ago

Some users notice that their Plugzio Universal+ device reports charging at 12 A instead of 16 A. This is expected behavior in many installations. The Universal+ does not control or limit charging current. It is a monitoring and access‑control device only—it measures consumption but does not regulate power flow

Charging current is determined by three components:

  • The wall outlet and electrical circuit

  • The portable EV charger (“charging brick”)

  • The vehicle’s onboard charging settings

1. The Wall Outlet (Hardware Limits)

The most common reason for reduced current is the rating of the outlet the Universal+ is plugged into. Electrical codes limit continuous loads—such as EV charging—to 80% of the circuit’s maximum rating.

Outlet Type

Max Current Rating

Max Continuous Load or EV Charging Limit

NEMA 5‑15R (standard household outlet)

15A

12A

NEMA 5‑20R (T‑shaped 20 A outlet)

20A

16A

If the Universal+ is connected to a 15 A outlet, the EV charger will automatically limit itself to 12A to avoid tripping the breaker or overheating the wiring.

2. The Portable EV Charger (Smart Safety Features)

The portable EV charger is the device that decides how much current to draw. Many modern chargers include protective logic that reduces current when they detect unstable or poor‑quality power.

Voltage Drop & Its Impact

Standard 120 V outlets typically sit between 110 V and 120 V. When a high load is applied, voltage naturally drops. Significant voltage drop can cause the EV charger to reduce current for safety.

Example:

  • Idle voltage: 120 V

  • Under 16 A load: drops to ~110 V

  • If voltage falls too far (i.e. below 110V), the charger may reduce to 12 A to keep the voltage above 110V

Common Causes of Voltage Drop

  • Long wiring runs: More distance = more resistance

  • Undersized or aging wiring: Older circuits may not maintain voltage under load

  • Shared circuits: Other devices on the same breaker reduce available voltage

  • Local grid load: High demand on the transformer lowers starting voltage

When voltage drop is detected, the EV charger will automatically reduce current to protect itself and the building’s electrical system.

3. The Vehicle Settings

Even if the outlet and charger can support 12 or 16 A, the vehicle may impose its own limits.

  • Onboard current limit: Many EVs allow the driver to set a maximum charging current.

  • Smart charging schedules: Some vehicles adjust current based on time‑of‑day, energy pricing, or battery conditioning.

If these settings are configured to reduce current, the vehicle will not draw the full 16 A or 12 A

Summary

If a Plugzio Universal+ device reports charging at 12 A instead of 16 A, the most likely causes are:

  • The outlet is a NEMA 5‑15R, which is limited to 12 A continuous load

  • Voltage drop is causing the EV charger to reduce current

  • The vehicle or portable charger has applied a safety‑related current limit

The Universal+ device simply reports the electrical flow negotiated between the outlet, the EV charger, and the vehicle.

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