The P-Bus Battery Management Shunt SHX 648 from philippi is a digital shunt for the P-BUS onboard network, designed for high currents. It is installed in the negative line of the battery and measures current, voltage, and capacity from 10 mA to 600 A continuous current with ±0.5% accuracy — for systems with bow thrusters, winches, or powerful inverters.
- Detects quiescent currents from 10 mA — despite a measuring range of up to 600 A continuous current
- ±0.5% accuracy across the entire measuring range, not just the upper part
- Measure starter battery voltage directly, without a second shunt
- Detect battery temperature directly at the shunt via the TEMP-BT temperature sensor
- Galvanically isolated P-BUS connection — even battery banks separated from the onboard network can be monitored
Resolution and Accuracy across Five Orders of Magnitude
The philippi SHX 648 measures from 10 mA to 600 A — this is a range over five orders of magnitude, and the accuracy of ±0.5% applies across the entire range. This is where a battery management shunt differs from a simple current measurement.
Practically, this means two things. Downwards: A quiescent current of 30 mA — a forgotten device, electronics in standby — drains approximately 0.7 ampere-hours from the bank per day. The SHX 648 detects it, even though it is designed for twenty thousand times that amount. Upwards: The peak when the bow thruster starts is also measured with the same accuracy and correctly included in the balance.
Because the state-of-charge indicator is a continuous ampere-hour calculation, measurement errors accumulate over time. Consistent accuracy is therefore not a comfort feature but a prerequisite for the display to still be accurate after two weeks.
Starter Battery and Temperature — Without a Second Shunt
The voltage of the starter battery can be measured directly at the SHX 648; a second shunt is not required for this. This covers the most practically important case: recognizing that the starter battery has not been recharged for weeks. A second shunt is only needed if a complete current balance with state of charge is also desired for the second bank.
The battery temperature is also detected directly at the shunt: The TEMP-BT temperature sensor is connected to the SHX 648, and the temperature, in addition to current, voltage, and capacity, is displayed on the system monitor — without a separate temperature interface.
Installation and Connection
The SHX 648 is installed in the negative line of the battery and is designed for systems with high energy demands, such as bow thrusters, winches, or powerful inverters. Connection is made via an M16 connection bolt; the SAS 4 shunt connection bar is available to match, allowing multiple cable connections — sensible, because only one cable belongs to the battery negative terminal, namely the one to the shunt, and everything else goes to the load side.
For consumer batteries with lower current requirements, the identically constructed SHX 348 is the suitable alternative.
| Parameter | Value |
|---|---|
| Current carrying capacity | Continuous current 600 A (800 A for 1 min, 2500 A for 0.5 s) |
| Measuring range | 10 mA – 600 A |
| Accuracy | ±0.5% across the entire measuring range |
| Current consumption | 6 mA at 12 V, 4 mA at 24 V |
| Operating voltage | 8–60 V |
| Connection | M16 bolt, P-BUS via M12 |
| Temperature measurement | directly at the shunt via TEMP-BT temperature sensor |
| Dimensions | L 185 x W 44 x H 75 mm |
| Article no. | 0 7100 0648 |
| Matching accessories | Shunt connection bar SAS 4 (Article no. 0 8000 9014) |
Compatibility
The SHX 648 works with the P-BUS system monitors PSM3, PSL, and PSL Plus, as well as all other P-BUS components of the philippi onboard system. For temperature measurement, the TEMP-BT sensor is connected directly to the shunt; for the load side, the SAS 4 connection bar fits the M16 bolt.
Frequently Asked Questions
How accurately does the SHX 648 measure?
With ±0.5% across the entire measuring range from 10 mA to 600 A continuous current. The consistent accuracy over the entire range is the prerequisite for the state-of-charge display not to drift over days.
Why does a 600 A shunt measure from 10 mA?
Because quiescent currents are in this order of magnitude, and they are exactly what drains a bank over weeks. A device with 30 mA draws approximately 0.7 ampere-hours from the bank per day — the SHX 648 detects this, even though it is designed for many times that amount.
Do I need a second shunt for the starter battery?
No. The starter battery voltage can be measured directly at the SHX 648. A second shunt is only necessary if a complete current balance with state of charge is also desired for the second bank.
Can I also measure the battery temperature?
Yes, via the TEMP-BT temperature sensor, which is connected directly to the SHX 648 — a separate temperature interface is not required for this.
Is the connection galvanically isolated?
Yes, the P-BUS connection is galvanically isolated. This allows even battery banks separated from the onboard network to be monitored.
Which distribution rail fits the SHX 648?
The SAS 4 shunt connection bar, suitable for the M16 connection bolt.
Order now or consult our team with questions about the appropriate shunt size for your onboard network.
⚠️Safety data sheet can be found under Downloads!
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