PBE Article | Dual Battery Systems

Dual Battery Systems | Starting point…

To start off, we are going to look at the basic definition of a Dual Battery System, why we need it and how it works. We also cover the PBE dual battery system options and why we recommend our systems.

Basic Dual Battery System Definition

Often also called an Auxiliary Battery System.

The system consists of an additional (auxiliary) battery that is used to power accessories like fridges, lights, air pumps, water pumps, power inverters and many other DC devices. This ensures that the engine cranking battery (also know as main battery) is safe and isolated from the additional loads, which ensures that the vehicle battery is never drained or depleted by the additional accessories.

In simple terms, a dual battery system ensures that additional accessories can be powered by an auxiliary battery without draining a vehicle engine battery.

The system can consist of more than one auxiliary batteries (the largest system we have done in 2016 so far was 8 auxiliary batteries which is safely charged by various methods including vehicle alternator charging, without altering the alternator in any way).

The additional batteries can be installed in various locations:
– Inside the vehicle inside the engine compartment (provided that space is available)
– Inside the vehicle load bin or passenger compartments
– Inside a trailer, caravan or camper (where ever space is provided)

What is a PBE Dual Battery System?

A PBE Dual Battery System is designed for various applications, of which the heavy duty off-road and military off-road applications are most important. PBE Dual Battery Systems consist of:

  • High Power Battery Charging Systems (within limits of battery and vehicle specifications)
  • High Reliability & Heavy Duty Components
  • High Quality Systems & Products
  • Safety features for safe operations and system protection

The Auxiliary Battery needs charging, how do we do it?

Running the fridge and other DC accessories, we make use of the limited energy (or power) stored in a battery (or battery bank – more than one battery).

The battery will stop supplying power when depleted (and damage accordingly) if it is not recharged frequently and adequately by a proper charging system / method.

We can make use of the following battery charging methods, either independently or in conjunction with each other, working together as a controlled system:

  1. Dual Battery Charge Control System installed in a vehicle
  2. Solar Charging System (portable or fixed)
  3. Battery Charger (portable or fixed)
    a. AC – DC Battery Charger (also called Mains or 230V AC Chargers)
    b. DC – DC Battery Charger (also called Battery – Battery Chargers or Power Transfer Unit – PTU)

1. Dual Battery Charging Systems (Vehicle charging):

The most cost effective system, relating to power output performance, is the vehicle charge system. The vehicle alternator is the powerful source used to re-charge the auxiliary battery – while driving, or standing with engine running (most of the times even at idle).

For this purpose, PBE designed its MacroMaxi Dual Battery Charge Controller.

The system can be set up at different power ratings for battery charging options:

  • 20 – 22 Amp average recharge rate
  • 25 – 28 Amp average recharge rate
  • 30 – 35 Amp average recharge rate
  • 38 – 40 Amp average recharge rate (usually 2 or more auxiliary batteries)
  • 45 – 50 Amp average recharge rate (usually 2 or more auxiliary batteries)

We look at the alternator specifications before we attempt high power charging rates, especially if the client has 2 or more auxiliary batteries in the system. PBE always ensure safety of the system to work in a controlled manner.

Choosing a powerful system can ensure minimal charging time to restore a certain amount of power back into the battery. This is important especially if you do not want to drive for hours and hours just to get enough energy to keep the fridge running through the night.

With a 30 Amp recharge rate, we can roughly charge 1 hour to replace 10 fridge running hours into the battery, ensuring enough energy was stored with only 1 hour engine running time.

1 Hour Engine Running = 10 Hours for the Fridge!
(Using at least a 30 Amp Charge System with an average DC Camping Fridge)

Key Benefits of PBE Vehicle Charging Systems (alternator charging):

  • Cost-effective – High power output, reliability, extremely low maintenance, long serivce life
  • Very low risk – The PBE Dual Battery Charging Control system risk of failing is extremely low
  • High reliability – The PBE Dual Battery Charging Control system is highly reliable
  • High power output – The PBE Dual Battery Charging Control system ensures high power charging
  • Safety – The PBE Dual Battery Charging Control system incorporates various safety & protection features
  • Alternator Protection – The PBE Dual Battery Charging Control system protects against alternator overload

2. Solar Charging Systems:

Using solar is an effective, silent and green way of re-charging batteries, where the source is the sun. Portable solar power systems, fixed systems, combination between portable and fixed solar power systems are all available at P. B. Enterprises cc.

Solar power is less cost-effective when compared to a 45 Amp dual battery charging system, with regards to power delivery, although it is convenient, silent and can be very effective during sunny days at the campsite, keeping the batteries charged up while the fridge is running to keep everything cool. Don’t forget, it is quite “green”!

Key benefits of PBE Solar Charging Systems:

  • Effective battery charging during sunny days – provided the correct system is installed
  • Silent power – no engines running, no noise to tolerate
  • “Free power” – after initial capital spent, solar systems supply free power using the sun for quite a long period
  • Long life expectancy – Typical solar power system life between 20 – 30 years
  • Safe to use – no toxic gasses

3. Battery Chargers (Portable or Fixed):

Battery Chargers (heavy duty) manufactured by PBE is durable, powerful and made for off-road use. It can take the punch of shaking and vibrations inside the vehicle, trailer or caravan. It will go where your vehicle will take you! The systems are designed to charge batteries quicker, taking the voltage up and supplying high current boost for the first hour.

All PBE Battery Chargers and Trailer or Caravan Power Units are designed with a 3-stage battery charging function, in which the float stage is used for longer term charging while camping with power. So if you have a portable battery box, you can use the PBE Battery Chargers to safely boost-charge the battery quicker from 230 V AC power from national supply network or generator (yes, the PBE Battery Chargers can be connected to 230V AC generators to re-charge batteries!!!).

The trailer/caravan power units are battery chargers with more functionality and features for use in off-road caravans and trailers. The same charging functions are available as in the standard portable PBE Battery Chargers.

Key benefits of PBE Battery Chargers:

  • Mains / Generator Charging – Connect the charger direclty to a 230V AC supply and re-charge the batteries properly in less time
  • High Power Charging – PBE offer 30 Amp, 60 Amp and higher power rating chargers for camping and quick re-charge when charge time is limited
  • Safe Charging Features – 3-Stage Battery Charging including long term float charge to ensure batteries can be connected to charger for long periods
  • Over and Under Voltage Protection
  • Reliable and Durable – The heavy duty chargers are designed and manufactured especially for off-road and military applications

4. Battery to Battery Chargers (also DC-DC Battery Chargers)  Also see Article 09-2013 about DC-DC charging

The Battery to Battery Chargers manufactured by PBE converts energy to be transfered from one battery to another. PBE Power Tansfer Unit (PTU)

Typical use:

Normally, a trailer can be left at a camping site with a fridge running from its battery, while the vehicle is taken away for which ever purpose, sightseeing, game drive, or where ever you are able to drive for a certain period of time. The vehicle engine can provide charging power to an auxiliary battery in the vehicle, and maybe even run a secondary fridge as well.. By having a proper PBE Dual Battery Charge System, the battery can be charged in minimal time.

When returning to the camping site, the trailer can be connected to the vehicle, and the PTU can be activated. It will use the energy in the battery charged by the vehicle, to charge the battery in the trailer. This ensures that no gasses or noises at the campsite.

A proper PBE Solar Power System, can also be used, thus while charging the trailer batteries, the vehicle batteries can be charged with the overflow of power as well.

Key Benefits of PBE Battery to Battery Chargers:

  • No noises and gasses at campsite – charge trailer battery over night in silence
  • Effective & Efficient System – Good efficiency ensures less power wasted
  • Reliable & Safe – System is quite reliable with ample protection features and battery low cut off
  • Good alternative where solar is not possible
  • No generator required

Why PBE?

We have learnt through experience that Africa is a tough place, off-road use puts a lot of strain on all products in the market. The PBE systems has thus far performed extremely well under the harsh conditions of off-road use since 1995.

The greatest dangers to products are shaking, vibration and climate.

PBE design systems to last, we know that you are going to drive off-road, we know you are crossing rivers, we know you are driving through mud, over rocks, bad roads and through all of this, you still want your battery system to perform at its best – then fit the PBE dual battery charging system!

The MacroMaxi Dual Battery Charging System from PBE is;
Simple to understand, easy to use
– Reliable, less maintenance and definitely much lower risk
– Powerful, recharges batteries quicker within specified limits
– Rugged, water-proof and built to last
– Intelligent, knowing when to charge and when to protect
– Efficient, approximately 98% efficient at 45 Amp load!
– Always customizable according to power requirements
– Safe to use with various safety and protection features
The simple wiring diagram of the PBE system
PBE Dual Battery Wiring Diagram 1

Why do I need a dual battery system?

Most 4×4 and outdoor enthusiasts want to use fridges while visiting remote areas for refreshments and food. If you are going to camp or overnight in remote areas for extended periods of time during your holiday, we recommend fitting a dual battery system to power the DC fridge, camping lights (we recommend LED camping lights). The auxiliary battery will prevent that the vehicle battery is drained and depleted the time you want to drive off again.

We don’t want to use the engine starting battery to power the fridge and lights.

Why PBE?

PBE have the necessary knowledge and technical skills to install the system professionally, we have designed our systems carefully to be the best available in the market, making it the most powerful, most reliable system to date. Our products are made for the great outdoors!



In the next article, we will discuss the quality features and things to look out for when deciding on a dual battery system, or general outdoor power system.  


Typical issues covered:

Is your system really designed for outdoor and off-road use?

Can it really take the shaking? What about the heat?

What kind of risks do you take with which systems?

Will the system really give enough power?

Is it really reliable?

Is the quality good? Is the installation up to standard, or will it fail you?

What is something goes wrong? Is your service provider a specialist, and always available in case of emergency or give advice or help? Do you meet the designers and installers personally, or did you only meet the sales rep? Do you get personalized service? Do they take all your needs into consideration?

Bush Lapa Caravan Power System upgrades by PBE


PBE recently upgraded Bush Lapa Caravan Power Systems to the “PBE Spec”.

PBE Bush Lapa Power Panel 6B  panel-8a

All new panels feature a black design, with various options to choose from. See more Bush Lapa Installations in the Caravans Gallery and scroll down to the Bush Lapa gallery
Power System upgrades include:

Heavy Duty PBE 30 Amp and 60 Amp Battery Chargers
– Charging Batteries much faster from Mains 230V AC
– 3-Stage Battery Charging Features, including Boost and Float Charge stages
– High Power Solar Input capability option (300W+)

12 V DC Distribution and Battery Management System
– Including Battery Low Disconnect (Battery Protection)

Custom Power Panels with a large list of options to choose from including:
– Battery Power Level Meters
– Load and Charge Current Meters
– Mains Distribution
– DC Power Distribution Systems
– Various DC Power Plugs including USB Ports
– Water level meters and sensors (with specific design criteria)
– Inverter Power Control and Management Systems

SOLAR POWER (Fixed / Removable Systems)
Fixed or removable Solar Panel options, including portable options to suite your specific needs.

bush-lapa-200w-3 bush-lapa-160w



PBE Bush Lapa Vehicle Charge Connection

Bush Lapa PBE Door LED Light

PBE Bush Lapa Fully Equipped Power Control Panel