# Charging Current Limits

The station configuration holds two current values that constrain each other:
**Max Current**, the highest current the station may offer a vehicle, and
**Mains Fuse**, the rating of the supply fuse the installation sits behind.
The rule applies from firmware 2.3.81 on all station models.

## The rule

**Mains Fuse is never smaller than Max Current.** The charging current must
not exceed the fuse protecting the supply, so the configuration interface
raises any smaller entry to the current Max Current value when the field is
left.

With Max Current at 24 A:

| Entered Mains Fuse | Stored |
| --- | --- |
| 16 | 24 — raised to Max Current |
| 24 | 24 |
| 30 | 30 — any value ≥ Max Current is kept |

The value a Mains Fuse entry jumps back to is always exactly the Max Current
configured on the station, which makes it a quick way to read that setting
back.

## Lowering the Mains Fuse

Raising Max Current pulls the Mains Fuse up with it, but the fuse cannot be
lowered past Max Current. To set a smaller fuse rating, change the two values
in this order:

1. Lower **Max Current** to the value you want (for example 16 A).
2. Enter the **Mains Fuse** (for example 16 A).
3. **Save.**

Doing it the other way round does not work: the fuse entry is raised back to
the old Max Current before it is ever stored.

## Validation and stored values

* The field must not be left empty. From firmware 2.4.0 an empty Mains Fuse is
  rejected on save.
* The validation message names the absolute lower bound of 1 A. The value is
  additionally checked against Max Current, so an entry well above 1 A is
  still adjusted or rejected when it falls below Max Current.
* Because a smaller entry can be corrected as part of saving, read the value
  back after saving to confirm which fuse rating the station now holds.

## After a firmware update

Firmware before 2.3.81 does not apply this check, so a configuration saved
back then can hold a Mains Fuse below Max Current. Once the station runs
2.3.81 or newer, that stored pair fails validation and blocks saving any
setting on the page — including settings unrelated to the two current values.
Set Max Current and Mains Fuse to a consistent pair once after the update, and
saving works normally again.