A battery monitor shows you exactly how much energy you have left in your leisure battery. Guesswork leads to either running out of power or never using your battery's full capacity. The Victron BMV (Battery Monitor) series is the gold standard in the campervan world.
Verdict
The BMV-712 with Bluetooth is the best choice for most van builds. Install it during the electrical fit-out and you will never wonder how much battery you have left.
Models
| Model | Features | Price |
|---|---|---|
| BMV-702 | Voltage, current, Ah, SoC, temperature | £120-140 |
| BMV-712 | Same + Bluetooth | £150-180 |
| SmartShunt | Same as BMV-712 but shunt-only (no display) | £100-130 |
Installation
The BMV shunt sits in the negative line from your battery. All loads and chargers must return to the battery through the shunt (not direct to chassis). Installation steps:
- Disconnect battery negative
- Mount the shunt on a non-conductive surface
- Connect battery negative to shunt "BATTERY MINUS" terminal
- Connect all loads/chargers negative to shunt "LOAD MINUS" side
- Run the RJ12 cable from shunt to display
- Connect the positive power wire to a switched 12v source
- Configure battery capacity in the setup menu
Configuration
Enter your battery's Ah capacity and Peukert exponent (typically 1.05-1.25 for LiFePO4, 1.25 for AGM). The BMV auto-learns your battery's efficiency over the first 3-5 charge cycles.
Accuracy
After 10 charge cycles, the BMV is accurate to within 2-3% of actual state of charge. Critical for LiFePO4 batteries where voltage is a poor indicator of remaining capacity (LiFePO4 voltage stays flat at 13.2V from 20% to 80% SoC).
