Read charger availability indicators

The Chargers tab in expreScan is the driver’s at-a-glance view of every unit they can use. Before you tap into a specific charger, the list itself tells you which ones are reachable, which one is closest to you, and which are filtered out of view. This article explains what those indicators mean and how the app decides what to show.

The model

The Chargers tab combines three independent signals — reachability, proximity, and filter state — into a single ordered list.

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flowchart TD
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  A[Charger list from server] --> B{Filter applied?}
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  B -->|All| C[Include every charger]
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  B -->|Online only| D[Drop offline chargers]
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  C --> E{Any charger within ~150 m?}
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  D --> E
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  E -->|Yes| F[Promote closest to primary card]
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  E -->|No| G[All chargers render as rows]
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  F --> H[Remaining chargers as secondary rows]

Reachability

Each entry carries an online state derived from its OCPP connection to SteVe. A charger is online when SteVe has an active websocket from it; otherwise it’s offline. The list row shows this as a status dot and label. Offline chargers can still be opened — the detail screen will show their last known state — but they won’t respond to a start request until they reconnect.

Proximity

When the app has location permission, it streams the device’s location while the Chargers tab is visible. If any charger is within roughly 150 m, the closest one is promoted into a tall primary card at the top of the list, with a distance readout. Everything else falls into the standard row list below it.

If no charger is nearby, or if location permission is denied, every charger renders as a regular row and no primary card appears. Distance labels still show on rows when a location fix is available.

Filter state

The toolbar filter menu lets you narrow the list to online chargers only or show all chargers. The filter is applied before proximity promotion, so the primary card is always chosen from the chargers you can currently see.

The single-charger fast path

If — after filtering — the list contains exactly one charger, the app pushes its detail screen automatically the first time it resolves. Tap back and you return to the list (which will not auto-push again in the same session), so the behavior gracefully gives way as more chargers appear in your fleet.

Why it works this way

A driver standing in front of a charger doesn’t want to scan a list — they want the unit in front of them to be obvious. Proximity promotion solves that without forcing the driver to scan a sticker: when you walk up to a charger, it floats to the top on its own.

Reachability is surfaced honestly rather than hidden. An offline charger is still listed because the cause is often transient (network blip, reboot), and the driver may want to open the detail screen to see the last reading or trigger a refresh. Filtering it out by default would hide useful state; offering an “online only” filter lets drivers opt into a cleaner view when they want one.

Location updates start only when the Chargers tab is on screen, and stop when you leave it. That keeps the iOS status-bar location indicator honest — the app is only “using your location” when it’s actively ranking chargers by distance.

What this means for you

A tall card at the top means you’re within ~150 m of that charger. It’s the closest one to you right now.
A green status dot means the charger is connected to SteVe and can accept a start request. A grey or red dot means it’s offline; open it to see when it was last seen.
No primary card means either you’re not near any charger, or the app doesn’t have a location fix yet. Pull to refresh, or grant location permission in Settings.
A list of one pushes you straight into the detail screen on first load. Tap back to see the list.
The filter menu in the top-right toolbar lets you hide offline chargers without losing them — flip back to “All” to see them again.