The P-Bus Battery Management Shunt SHX 348 from philippi is a digital shunt for the P-BUS onboard electrical system of yachts, motorhomes, and off-road vehicles. It is installed in the battery's negative line and measures current, voltage, and capacity over the entire range from 10 mA to 300 A with ±0.5% accuracy—the basis of any reliable battery monitoring.
- Detects quiescent currents starting from 10 mA, revealing creeping consumers that can drain a bank over weeks.
- ±0.5% accuracy over the entire measurement range — not just in the upper part.
- Directly measures starter battery voltage without a second shunt.
- Measures battery temperature directly at the shunt using the TEMP-BT temperature sensor.
- Galvanically isolated P-BUS connection — allows monitoring of battery groups even when separated from the onboard electrical system.
Resolution and Accuracy: The Real Difference
A shunt is only as good as its smallest reliably measurable current. The philippi SHX 348 starts at 10 mA — and that's precisely where hard-to-find problems reside. A forgotten device with a 30 mA quiescent current draws about 0.7 amp-hours per day and five per week. A shunt that only measures above a good ampere will not see this; the bank will still be empty.
The second half is the accuracy of ±0.5%, and that applies over the entire measurement range — from milliamp quiescent current to the inverter's startup current. This is a prerequisite for an amp-hour balance to be accurate over several days: in a state-of-charge indicator, measurement errors accumulate because each measurement value is incorporated into a running calculation. A shunt that is only accurate at high currents will provide a reading that slowly drifts off in standby mode.
Starter Battery and Temperature — Without a Second Shunt
The starter battery voltage can be measured directly at the SHX 348; a second shunt is not necessary for this. This covers the most common fault scenario: a starter battery that has not been recharged for weeks because separating relays or charging converters are no longer working. A second shunt is only needed if a complete current balance with state of charge is also desired for the second bank.
Similarly, the battery temperature is measured directly at the shunt: the TEMP-BT temperature sensor is connected to the SHX 348, and the temperature appears on the system monitor in addition to current, voltage, and capacity. A separate temperature interface is not required for this.
Installation and Connection
The philippi SHX 348 is installed in the negative line of the battery and continuously reports its values to the P-BUS network; from current and voltage, it calculates the current battery capacity, displayed in color in the battery symbol of the system monitor. Power is supplied via the existing voltage measurement line — an additional power cable is not required. The power connection is made via an M8 terminal stud, and the P-BUS connection via an M12 connector.
For systems with higher currents or powerful consumers, the identical but more powerful SHX 648 is available.
| Parameter | Value |
|---|---|
| Current carrying capacity | Continuous current 300 A (600 A for 1 min, 1500 A for 0.5 s) |
| Measurement range | 10 mA – 300 A |
| Accuracy | ±0.5% over the entire measurement range |
| Current consumption | 20 mA (5 mA in sleep mode) |
| Operating voltage | 8–64 V |
| Connection | M8 stud, P-BUS via M12 |
| Temperature measurement | Directly at the shunt via TEMP-BT temperature sensor |
| Dimensions | L 118 x W 40 x H 65 mm |
| Article No. | 0 7100 0348 |
Compatibility
The SHX 348 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. If the output of a charging source or the consumption of an individual device is also to be recorded, the Energy Shunt SHX 300-L supplements the system.
Frequently Asked Questions
How accurately does the SHX 348 measure?
With ±0.5% over the entire measurement range from 10 mA to 300 A. Both are crucial: the fine lower limit that makes quiescent currents visible, and the consistent accuracy, without which a state-of-charge display would drift over days.
Why is measurement from 10 mA important?
Because quiescent currents are in this order of magnitude. A device drawing 30 mA will draw about 0.7 amp-hours from the bank per day — invisible to low-resolution devices, noticeable after a week.
Do I need a second shunt for the starter battery?
No. The starter battery voltage can be measured directly at the SHX 348. A second shunt is only needed if a complete current balance with state of charge is also desired for the second bank.
Can I also measure the battery temperature?
Yes, using the TEMP-BT temperature sensor, which is connected directly to the SHX 348. The temperature appears on the system monitor in addition to current, voltage, and capacity; a separate temperature interface is not required.
Can I monitor a battery isolated from the onboard electrical system?
Yes. The galvanically isolated P-BUS connection allows monitoring of isolated battery groups, for example, an emergency battery for radio equipment.
Do I need an additional power cable?
No, power is supplied via the existing voltage measurement line.
How high can the current be for a short time?
For short periods, 600 A for 1 minute or 1500 A for 0.5 seconds are permissible, with a continuous current of 300 A.
Order now or contact our team for advice on the right shunt size for your onboard electrical system.
⚠️Safety data sheet can be found under Downloads!
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