BLACK OPS BUSH TRUCK BUILD

Of all the popular upgrades that we do to our 4WD vehicles, the management of the 12 Volt power system is arguably toughest get right. power system of a vehicle consists of a battery, a charging system and a network of electronic devices that manage this power to ensure that the vehicle starts, that the now depleted battery is charged back up to full capacity as quickly as possible and that all of the standard electronic devices of the vehicle are properly and sufficiently powered. This is no small feat, but this system works.

As overlanding enthusiasts, we have additional requirements for power that the standard vehicle is not sufficiently geared for. This is especially true when we venture away from places that offer 220V plug-in power. We want to run an electric fridge/freezer to keep our food and beverages cold, we need lighting after dark, we have cameras, phones, laptops, drones, etc. that have batteries that need charging, and some of us just cannot get by without our DSTV fix…

In these situations it is necessary to upgrade the availability of power in the vehicle and then ensure that this power is readily available, sufficiently replenished, and, most importantly, does not affect the functionality of the vehicle’s original power system. The simplest way to achieve this is to install an additional battery to provide the power needed for these additional appliances. This additional battery will thus have a different function to the vehicle’s main battery.

Cranking & auxiliary batteries

The primary function of the main battery is to provide power to turn the engine starter motor and start your vehicle engine. We refer to this battery as the cranking battery. The cranking battery is also responsible for functions that include the ignition and lighting and they are also sometimes referred to as “SLI” batteries. Cranking batteries are typically Flooded or Wet Cell Lead-Acid batteries. They are great for large current delivery for a short time when cranking an engine. Typically this action would consume between 3 and 5% of the battery capacity. It is important to note that once the engine has started and the alternator starts to deliver charge to the battery, it is the alternator that supplies power to the vehicle electronic system. The cranking battery will accept a large charging current to get back to full in a short period of time, ideally 10 to 15 minutes under perfect conditions. These batteries are relatively inexpensive and are suitable for quite adverse operating conditions. They do not do well with prolonged deep discharge cycles such as running lighting and refrigeration overnight. It is essential that your alternator and charge system is working correctly to ensure long service life. The secondary function of the cranking battery is to provide extra power to the vehicle electronic system when the requirements exceed the supply from the alternator.

“Cranking batteries do not do well with prolonged deep discharge cycles such as running lighting and refrigeration overnight”

For the auxiliary battery application one needs