This Victron Smart BatteryProtect review covers Victron’s low-voltage disconnect for 12V and 24V systems. It sits between the battery and your DC loads. When battery voltage falls below a set level, it switches the loads off before the battery is damaged or the engine can no longer start. It comes in 65A, 100A and 220A versions, uses MOSFETs instead of a relay, and is set up over Bluetooth.
Electrical work can be dangerous: follow the manual, fuse and size every cable correctly, and use a licensed electrician for anything connected to household wiring.
Victron Smart BatteryProtect Review: Specs
| Spec | BP-65 | BP-100 | BP-220 |
|---|---|---|---|
| Max continuous load current | 65A | 100A | 220A |
| Peak current (30s) | 250A | 600A | 600A |
| Operating voltage | 6-35V | 6-35V | 6-35V |
| DC connection | M6 | M8 | M8 |
| Weight | 0.2kg | 0.5kg | 0.8kg |
Source: Victron Smart BatteryProtect 12/24V 65A/100A/220A datasheet.
Shared specs: 12/24V auto-detect (one time only), default disconnect at 10.5V or 21V and reconnect at 12V or 24V, overvoltage cut-off at 16.3V or 32.6V, current draw about 1.4mA with Bluetooth on, electronics potted to IP67 (connections IP00), full load from -40°C to +40°C.
What We Like
- No sparks. MOSFET switching means no relay contacts, which Victron calls ignition proof.
- Sensible delays. Loads switch off 90 seconds after voltage drops below the threshold and reconnect 30 seconds after it recovers. Starting an engine won’t trip it.
- Alarm output. After 12 seconds below the threshold it drives a buzzer, LED or relay (max 50mA).
- Li-ion mode. A lithium BMS can control it, so loads switch off on a BMS signal. It can also serve as a charge disconnect when oriented correctly.
- Doubles as a system on/off switch through its remote input.
- Very low standby draw, which matters for a lithium battery after a low-voltage shutdown.
What to Watch
- Never connect an inverter’s DC input through it. Victron says the capacitors trigger short-circuit protection, and reverse current can damage the unit. Use the BatteryProtect to switch the inverter’s remote on/off terminal instead.
- One-way current. Current may only flow from IN (battery) to OUT (load).
- Voltage detection happens once. If you move it to a different system voltage, reset it via the programming procedure or Bluetooth.
- Derating. At 50°C it is rated for 60% of nominal load.
Who It’s For
Vans, boats and RVs with DC loads on a battery that also starts an engine, or any lead-acid or lithium bank that needs protection from over-discharge. Systems where a lithium BMS has a load-disconnect output can use it as the switch.
The Three Operating Modes
- Mode A: Buzzer or LED (default). On undervoltage, the alarm starts after 12 seconds, the load disconnects after 90 seconds, and it reconnects after 30 seconds. On overvoltage, the load disconnects immediately.
- Mode B: Relay. The alarm output drives a relay instead.
- Mode C: Li-ion. A lithium BMS’s load-disconnect output controls it through the remote H input. After three restart attempts following a low-cell shutdown, it stays off until the battery has been above 13V (26V) for 30 seconds.
Set the mode in VictronConnect or with the PROG-pin-to-GND method in the manual.
Error and Warning Codes
| Code | Meaning |
|---|---|
| E0 | Calibration failure |
| E1 | Short circuit |
| E2 / P2 | Over temperature / warning |
| E3 / P3 | Under voltage / warning |
| E4 | Over voltage |
| E5 | Configuration failure |
| E6 | Reference voltage failure |
| E7 | BMS lockout |
| E8 | Reverse current |
Source: Smart BatteryProtect 12/24V manual. The display blanks after 5 minutes to save power.
Common Mistakes
- Moved to a different voltage. Auto-detection runs once, so reset it in the app.
- Undersized for the load. Match it to the continuous load current and allow for heat.
Sizing Worked Example
Size a Smart BatteryProtect by the continuous current of the loads it switches, then check the startup surge against the 30-second peak rating. A 12V van circuit feeding a compressor fridge (about 5A running), LED lights (3A), a water pump (6A), a roof fan (3A) and USB charging (4A) totals about 21A. The BP-65 covers that with plenty of headroom, and its 250A 30-second peak handles motor starts.
A 220A circuit is a different situation. Check whether a large inverter belongs on the BatteryProtect at all; see the Common Mistakes section above. For a feed above 100A continuous, the BP-220 is the only model in the range.
| Load circuit | Continuous current | Suggested model |
|---|---|---|
| Lights, pump, fan, fridge, USB | up to about 50A | BP-65 |
| Above plus a diesel heater and a 12V fridge-freezer | 50–90A | BP-100 |
| Large DC distribution panel | 90–220A | BP-220 |
Where It Goes in the Wiring
- The battery positive goes to the BatteryProtect IN terminal, and the OUT terminal feeds the load fuse block.
- Run the ground wire to the battery negative; the unit needs it to measure voltage and to operate.
- Chargers, solar controllers and DC-DC chargers connect directly to the battery, not through the BatteryProtect.
- Fit a fuse between the battery and the IN terminal, sized for the cable.
- Set the disconnect and reconnect voltages to your battery maker’s figures before the first use.
Worked examples are arithmetic estimates from the published ratings above, not test results. Real numbers depend on temperature, cable runs, battery state and load.
For the complete spec sheet and current manual, see the Victron Smart BatteryProtect page.
Quick Setup Checklist
- Wire IN to the battery (through a fuse), OUT to the load fuse block, and the ground wire to the battery negative.
- Power it up on the system it will stay on, so the one-time 12V or 24V detection is correct.
- Open VictronConnect and choose Mode A, B or C to match your alarm and battery setup.
- Enter the disconnect and reconnect voltages from your battery maker.
- If you use the alarm output, keep the buzzer, LED or relay within the 50mA limit.
- Test by switching it off and on from the app before you rely on it.
Standby Draw in Practice
At about 1.4mA with Bluetooth on, the Smart BatteryProtect uses roughly 34mAh a day, or about 1Ah a month (estimate). That is small enough to leave a stored lithium or lead-acid battery protected for long periods.
FAQ
Which size do I need?
Match it to the maximum continuous current of the loads it switches: 65A, 100A or 220A.
Can I disable Bluetooth?
Yes, Victron allows Bluetooth to be disabled. The VictronConnect manual warns that on some products this is permanent, so finish setup first.
Can it disconnect a charger?
Victron’s manual describes using it to disable chargers without a remote port, wired the correct way round.
What happens if the voltage goes too high?
Loads are disconnected immediately at about 16.3V on a 12V system (32.6V on 24V), protecting sensitive DC equipment.
Can I use it as a main on/off switch?
Yes. A switch on the remote input turns the loads on and off without heavy cable.
Sources: Victron Smart BatteryProtect datasheet and Smart BatteryProtect 12/24V manual (victronenergy.com).
Related: LiTime 12V 50Ah LiFePO4 Battery Review, EcoFlow Delta 3 Max Van Life Leisure Battery, Pro Chaser 400W Car Power Inverter Review, plus the Victron Energy Guide