Equipment Tests > Batteries

Think of cold cranking amps as how hard the battery punches, the voltage as the speed at which it swings those punches and the reserve capacity or amp hour rating, its stamina...

Battery building blocks
There is also the matter of physical toughness - vibration and shock resistance is especially relevant to the 4WD scene. Conventional flooded wet cell batteries don't like too much rock and roll - the plates can break free of the battery chassis and the electrolyte (acid) can spill.

Sealed lead acid batteries, or gel cells, are chemically similar to conventional batteries, but as the name implies, the electrolyte is present in the battery in a gel form rather than as a liquid. Not only does this add toughness, but also the gel reduces characteristics such as sulfation that leads to early death. Absorbed glass mat (AGM) batteries are a step ahead again. In each AGM cell, the electrolyte - acid - is present in a fine fibreglass mat.

AGMs cannot only deliver a big-CCA punch for vehicle starting, but they happily tolerate being discharged to around 30 percent capacity without significant deterioration. They are ideal dual-purpose - starting and house - batteries because they hold more useable power and don't mind dishing it out.

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For 4WD use, any sealed lead acid battery is worth considering, and not just for performance reasons. Thanks to the fact they don't drop their guts, they don't prevent a vehicle being started after a rollover but do prevent injury and vehicle damage from spilled acid. Batteries designed for marine use are often the toughest of the lot. They are rated for complete inversion, immersion and ruggedness in a very hostile environment.

Spending the money to do things right when it comes to vehicle batteries can be the difference between great trip and a disastrous one.

WIRING
Wiring is a whole other subject, but it's important that any and all extra wiring (including terminals and fuses) be adequately rated for the power requirement. For instance, many enthusiasts run into problems with relocated batteries not being able to 'crank' the engine adequately as there is too much power loss (due to internal resistance) in the extra length of the battery/starter cables. Sourcing accessory power from the starter terminal (for instance, the coil or engine computer) can further complicate problems - the voltage available when the vehicle is being cranked may be below the threshold voltage these devices need to operate to run the engine.

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