If you add one thing to a 12V system, make it this. A SmartShunt measures every amp going into and out of your house battery and turns it into a state-of-charge percentage, like a fuel gauge. Before you have one you are guessing from voltage, and voltage lies — especially on lithium, which sits at almost the same voltage from 90% full to 20% full.

What you actually get

Open VictronConnect on your phone and you see: battery percentage, volts, amps in or out right now, and time remaining at the current draw. That last number is the useful one. “4 hours 20 minutes remaining” tells you whether to run the inverter tonight in a way that no voltmeter ever will.

It also logs history — deepest discharge, cycles, average depth — which is how you find out your battery bank is undersized before it dies rather than after.

No panel to cut

Unlike the BMV monitors, the SmartShunt has no separate display head. Nothing to find space for, nothing to cut a hole for, no cable to run to the dash. It bolts into the negative battery cable and talks to your phone over Bluetooth. On a build where every flat surface is spoken for, that is a real advantage.

Specifications

• 500A shunt, 50mV
• Battery voltage: 6.5V to 70V
• Bluetooth built in — VictronConnect app
• No display head required
• Weight: 0.95 lb
• Manufacturer part number: SHU050150050

Sizing

500A is plenty for most overland builds — it covers a 2,000W inverter at full tilt with room to spare. If you run a winch off the house bank or a 3,000W inverter, step up to the 1000A version.

⚠ WARNING: This product can expose you to chemicals which are known to the State of California to cause cancer, birth defects or other reproductive harm. For more information go to P65Warnings.ca.gov.