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BM2, BM6 and BM200 Bluetooth battery monitors, all tested with Voltsure.

Support for the BM7 (sold as the BM300 Pro) and the intAct Battery Guard is experimental: it’s built from their documented Bluetooth protocol, but hasn’t yet been tested on a real monitor. Voltsure marks them “Experimental” when you add them. Monitors sold under other brands and names may work too. If yours doesn’t work as it should, please tell us which monitor it is and what you see.

Monitor under a name Voltsure doesn’t recognise? In Add Battery, tap “Can’t see your monitor?” to list other Bluetooth devices nearby, and try yours: Voltsure works out which kind it is once connected.

You can add as many as you like and mix models freely, in Free and Pro. Every connected monitor reads at the same time.

Victron Smart devices that share live readings over Bluetooth (“Instant Readout”): SmartSolar solar chargers, SmartShunt and Smart battery monitors, Orion Smart DC-DC chargers and Blue Smart mains chargers. Older devices without Instant Readout can’t share their readings this way. Voltsure reads what they already broadcast, so there’s no extra hardware and nothing to connect. Victron devices are part of the Power System, a Voltsure Pro feature.

To add one, open the Power System, add the part (a solar charger, say), tap Read from a Victron Device… and pick it, then paste its encryption key. The key is in VictronConnect: tap the device, then ⚙︎, then ⋮ and Product info, check “Instant readout via Bluetooth” is enabled, and tap Show beside Instant readout details. The key is 32 letters and numbers. In Voltsure, Help → “Reading a Victron device” → How to Find the Key walks through it.

Readings arrive while Voltsure is open, on any screen or in CarPlay; iOS doesn’t pass them to apps in the background. Out of range, a device shows its last reading and how old it is.

• Check Bluetooth is on.
• Make sure the monitor is fitted to the battery.
• Stay within about 10 m of it.
• Close the monitor maker’s app, or disconnect the monitor there.
• A monitor connects to only one phone or iPad at a time. If another device nearby is connected to it, close the app there or turn off its Bluetooth.

These monitors measure voltage, not current. Charge is worked out from the voltage and is most accurate after the battery has rested with nothing running for an hour. Under load the true charge is at least the figure shown; just after charging it is at most the figure shown.

The status is estimated from battery voltage. Charging and discharging can’t be confirmed without measuring current.

• Charging At the battery type’s charging voltage, so a charger, alternator or solar is supplying power. It shows for 5 minutes after the last burst, as smart alternators charge in bursts.
• Rising The voltage has risen over the last two minutes. Charging is likely, though a load switching off does the same.
• Stable The voltage is holding steady. A charger and a load may both be running.
• Falling The voltage has fallen over the last two minutes, so something is likely drawing power.
• Low Below the battery’s low-voltage alert level.
• Unknown Not enough readings yet, as with a battery just added. The status needs ten minutes of stored readings, or two minutes of live ones.

Lithium (LiFePO4) voltage barely moves while charging or discharging, so a lithium battery often shows Stable.

Alerts need notifications allowed for Voltsure, and the app must not be force-quit: iOS only reconnects to monitors in the background while the app is still running. Alerts are Time Sensitive, so they come through Focus unless you’ve turned Time Sensitive notifications off for Voltsure in iPhone Settings.

Only while your iPhone is in Bluetooth range of the monitor, as the monitor sends its readings to your phone and nowhere else. If a battery that’s falling or near its alert level goes out of range for 10 minutes, you get a notification saying so, as there will be no alerts until it’s back in range.

Monitors keep the last few days of readings. The app downloads them when it reconnects, so gaps fill in once you’re back in range, as long as you return within a few days.

Voltsure Pro is a one-time purchase tied to your Apple ID and shared with your family through Family Sharing. On a new device, open the Voltsure Pro screen in the app and tap Restore Purchase.

No. No account, no servers, no location, no analytics. It works fully offline. See the privacy policy.