Blue Sea Systems – the complete range at philippi

At Philippi Elektrische Systeme GmbH in Remseck am Neckar. We are an official distributor of Blue Sea Systems in Germany and supply the complete range directly from our German warehouse — without import processing, customs duties, or waiting times from the USA. Orders can be placed via our online shop, and technical advice is provided in German by our team.

An ACR (Automatic Charging Relay) automatically connects two battery banks depending on the voltage: If the voltage rises above approximately 13.0 V due to an alternator, charger, or solar panel, the relay closes and both banks are charged. If the voltage drops below approximately 12.75 V, it disconnects again – so the starter battery cannot be discharged by consumers in the living area.

A manual battery master switch, on the other hand, requires active switching by the user and offers no automatic protection. In practice, both are combined: the ACR for charging operations, the master switch for maintenance and emergency shutdown.

Three points are decisive: continuous current, number of battery banks and operating environment.

• Continuous current: at least the starter current of your engine — typically 275–350 A for smaller diesel engines, 500 A and more for larger engines.
• Battery banks: an on/off switch is sufficient for a single bank; for two banks, a 1-2-BOTH-OFF selector switch is recommended.
• Environment: on petrol boats, a ignition-protected version according to ISO 8846 or UL 1500 is mandatory.

We will be happy to advise you on the specific design for your on-board electrical system.

What matters is not the starter current, but the maximum charging current flowing through the relay — essentially, the combined output of the alternator, charger, and solar controller.

A 120 A alternator is typically combined with a 120 A ACR. For smaller systems with solar and a charger, a mini ACR with 65 A is often sufficient. Important: If the ACR is also used for emergency starting (parallel connection), it must be rated for the starter current — in that case, 500 A versions are appropriate.

The fuse always protects the cable, not the consumer — it must therefore be below the current carrying capacity of the cable. Rough guidelines for 12 V DC in the marine sector:

• 2.5 mm² up to approx. 25 A
• 6 mm² up to approx. 50 A
• 16 mm² up to approx. 100 A
• 35 mm² up to approx. 150 A
• 50 mm² up to approx. 200 A

Cable length, installation method, and ambient temperature are also decisive. For high short-circuit currents directly at the battery — especially with lithium batteries — Class T fuses with high interrupting ratings are the right choice.

Ignition-protected components are designed so that any switching sparks generated cannot ignite a surrounding explosive atmosphere. This is required wherever gasoline vapors may occur - i.e., in the engine compartments of gasoline-powered boats and in rooms with gasoline tanks.

The relevant standards are ISO 8846 and UL 1500. It is not mandatory on diesel boats but is often chosen as an additional safety measure. Blue Sea Systems marks ignition-protected products accordingly in the data sheet.

Generally yes - switches, busbars, and fuse holders can be used regardless of the battery chemistry, as long as the current and voltage ratings match. Two points, in particular, should be noted for LiFePO4:

• Lithium batteries deliver significantly higher short-circuit currents, which is why fuses with a correspondingly high breaking capacity (Class T, partly ANL) are required.
• Voltage-controlled isolation relays should be adapted to the flatter voltage profile of lithium batteries - a DC-DC charging converter is often a better solution here than a simple ACR.

Tinned copper combines the high electrical conductivity of copper with a tin layer that protects the base material from oxidation and saltwater corrosion. Although brass and stainless steel are cheaper or mechanically robust, they have a significantly higher specific resistance.

At high-current connection points, this leads to increasing contact resistance, heat generation, and, in extreme cases, failures over the years. Blue Sea Systems therefore consistently uses tinned copper for busbars, studs, and connection points.

Yes, both systems can be easily combined in one onboard electrical system. Blue Sea Systems supplies classic onboard electrical hardware such as switches, relays, busbars, and circuit breakers, which operate independently of a bus system.

The Philippi P-BUS components such as the PCU or PSM3 handle digital monitoring and control. Typical setup: Blue Sea handles the power level (disconnecting, distributing, protecting), while Philippi handles the information and control level (measuring, displaying, switching).

Yes. The products are designed for 12 V and 24 V DC on-board electrical systems and are therefore suitable for motorhomes, panel vans, expedition vehicles and off-road conversions.

The marine design is even an advantage in vehicle construction: higher corrosion resistance, vibration-resistant connections and generously dimensioned contact surfaces. ACR isolation relays, PowerPost connection points and ST-Blade fuse distribution blocks are particularly often used in the camper sector.

Yes, as a distributor, we also carry accessories and spare components such as fuse holders, cover caps, terminal studs, and mounting accessories for existing Blue Sea installations.

If you know the part number (PN) of your existing product, we can directly assign the appropriate replacement or successor component. For discontinued series, we will inform you of the current equivalent.

The original documentation from Blue Sea Systems is in English. As a distributor, we support you with design, connection, and commissioning in German — by phone or email.

For more complex on-board networks, we can also assist with the creation of a wiring diagram, combining Blue Sea components and Philippi systems.