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A Journal of our Travels

Anderson Multipole Connectors

For high current applications, I use the Anderson SB series connectors. SB175 for battery charging, SB50 for medium current and solar panels.

Anderson SB50 Multipole Connectors

The SB50 is for higher current applications. rated at 50A.

The pins are the same as the Powerpole 75A housings.

The Anderson SB series is popular for 12v recreational vehicles, caravans and camper trailers.

Contacts come in 3 sizes:

6AWG

8AWG

10AWG

Anderson SB175 Multipole Connectors

The SB175 is for high current applications and when using large cable e.g. 2AWG. Rated at 175A

Contacts come in sizes:

0 AWG

1 AWG

2 AWG

4 AWG

6 AWG

Colour Usage

Colour

Anderson Recommended Usage

Yellow

12V

  • I use it for 12v DC battery voltage

Orange

18V

  • I also use it for unregulated solar output

Red

24V

  • also used by Warn for its 12 V winches,
  • and used by Amateur radio for 12V DC

Grey

36V

  • also used by Recreational vehicles for 12v battery voltage and unregulated solar output.

Blue

48V

There’s no global electrical standard body enforcing colour usage for Anderson connectors. The guidance comes from:

  • Anderson Power Products (original design intent)
  • Forklift and industrial battery conventions
  • Emergency services and communications networks
  • Widespread industry practice

Why colour matters with Anderson connectors

Anderson SB-series connectors are:

  • Genderless
  • Physically keyed by housing shape AND colour
  • Different colours will not mate, even if the contacts are identical.

This prevents:

  • Connecting different voltages together
  • Plugging chargers into the wrong battery system
  • Accidental high-current faults

In other words, colour is a mechanical safety lock.

Most common colour conventions (SB series)

Grey – 12 V systems

This is the most widely accepted convention, especially in:

  • 4WDs
  • Camper trailers
  • Caravans
  • Solar battery boxes

Typical uses:

  • Vehicle-to-trailer battery feed
  • Portable solar panels
  • General 12 V DC power distribution

It does mean that the same connector is used for 12vdc and unregulated solar panel output.

Red – 24 V systems

Common in:

  • Trucks
  • Heavy vehicles
  • Industrial battery banks

Using red helps prevent connecting a 24 V source into a 12 V system and overvoltage damage.

Yellow – Charging circuits (industrial origin)

In industrial environments, yellow is often used for Battery-to-charger connections

This convention is sometimes seen in Forklifts and Backup power systems

In recreational or touring setups, yellow is less common and usually avoided to keep things simple.

Blue – Higher-voltage DC systems

Often associated with:

48 V battery systems Telecoms and UPS installations

Rare in automotive and touring contexts, but common in fixed infrastructure.

Black / Green / Other colours

Technically available, but generally:not recommended unless you control the entire system Best avoided in shared or resale environments

Using obscure colours increases the risk that someone later assumes the wrong voltage.

If you’re setting up vehicle, trailer, or training systems:

  • Default to grey for all 12 V Anderson SB connectors for compatability with others
  • Never reuse the same colour for different voltages
  • Match colour usage consistently across vehicles, trailers, battery boxes, and chargers
  • Label if there is any possibility of confusion

The History of Multipole Connectors

The Multipole family was developed by Anderson Power Products to solve problems found in industrial DC power transfer, not small electronics or accessories.

By the mid-20th century, industries using:

  • Forklifts
  • Industrial battery chargers
  • Floor-cleaning machines
  • Material-handling equipment

all faced the same constraints:

  • Very high current
  • Repeated connection and disconnection
  • Exposure to vibration, dirt, and misuse
  • Operator safety (no exposed live pins)

Traditional male/female connectors were failing regularly in these environments. The core engineering breakthrough, Anderson’s key innovation was the flat, silver-plated copper contact under spring pressure, already proven in earlier designs.

For industrial use they paired this with:

  • Large contact surface area
  • Strong contact compression
  • A fully shrouded housing
  • A genderless design

This produced connectors that:

  • Run cooler under load
  • Maintain low resistance over time
  • Self-wipe on connection
  • Don’t rely on fragile pin alignment

This architecture becomes the foundation of the Multipole line.

Development of the SB (Single-Block) series

As battery-powered industrial equipment expanded, Anderson introduced the SB (Single Block) connector family.

Key design intent:

One-piece housing (stronger and more abuse-tolerant than modular housings) Fixed contact size per connector rating Colour-coded housings to prevent mis-mating of different voltage systems Touch-safe design when disconnected

The connector that becomes iconic in mobile power is the SB50.

Why the SB50 became the standard

The SB50 hits a practical sweet spot:

  • Nominal current rating around 50 A (higher in short duty cycles)
  • Compact enough for mobile installations
  • Large enough for serious battery and inverter work
  • Mechanically robust without excessive bulk

This made it ideal not only for factories, but eventually for:

  • Forklifts and battery chargers
  • Emergency power systems
  • Mobile communications trailers
  • 4WD dual-battery setups
  • Camper trailers and caravans

In effect, industrial engineering accidentally produced the perfect connector for touring power systems.

1970s–1990s: Industrial dominance

Through the late 20th century, SB connectors became a default in many industrial battery systems.

Important characteristics during this period:

  • Voltage-keyed housings to prevent dangerous cross-connection
  • Extremely high mating cycle life
  • Minimal voltage drop under sustained load
  • Compatibility across manufacturers using the Anderson pattern

No formal ISO automotive standard emerged — this was market dominance driven by engineering reliability.

2000s: Migration into automotive and touring markets

As vehicle-mounted battery systems increased in capacity, users started borrowing from industrial solutions.

The SB50 in particular moves into:

  • Bullbar-mounted power outlets
  • Winch connections
  • Trailer-to-vehicle battery feeds
  • Portable solar panels
  • Battery boxes and power stations

What appealed here was not convenience, but certainty:

You know when it’s connected You know it will carry the load You know polarity is correct

This is when the term “Anderson plug” becomes everyday language in Australia.

Why “Multipole” matters

The SB series is part of Anderson’s broader Multipole concept:

  • Same contact technology
  • Different housing formats
  • Different current classes
  • Scalable designs for everything from tens to hundreds of amps

It’s a system philosophy rather than a single product.

Like Powerpole connectors, Multipole connectors emerged through:

  • Industrial battery-system engineering
  • Iterative refinement in harsh environments
  • Feedback from field technicians rather than standards committees

Their longevity comes from performance, not branding.