Everything You Need To Know About Charging Systems
By Ryan Manson – Photography By The Author
A properly charged and maintained battery is a must for any classic car, but especially so when it comes to those equipped with all mod cons like EFI, digital gauges, A/C, and more. The more advanced the component, the more sensitive they seem to be to a steady, reliable 12V signal. Many systems, in fact, will cease to operate properly if provided with anything south of 11 V. That leaves a small margin of error when it comes to the alternator providing steady charge under normal driving conditions or to the battery itself if left to sit idle for too long a period. Leaving a trickle charger attached to that hot rod with an expectant slumber of a period over a week or so has become common practice.
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Charge System Considerations
But before we can even worry about proper maintenance of the battery and charging system, we need to be sure that the system’s wiring and cables are properly sized, fabricated, and run safely across the vehicle to further ensure the system’s reliability and performance. Long runs of battery and charging cables need to be sized properly, securely terminated, and properly protected.
Charging Cable Length & Gauge Size
As lengths increase, so does diameter size to overcome the resulting resistance in said wire/cable. For example, a 10-gauge wire on a 30-amp circuit has an acceptable run of around 10 feet. Extend the run of that wire another 2 feet and the size requirement jumps to 8-gauge. The longer the wire, the more resistance in the wire, hence the larger size to make up the disparity. Now, this is based on a rough set of specifications related to wire temp and percentage of acceptable voltage drop.
Battery Relocation Considerations
A wire that runs through the passenger compartment will see more moderate temps than one that runs from the engine compartment and alongside the exhaust, so other factors need to be considered as well, all based on individual circumstances. Like many things in the hot rod world, these are baselines and not hard and fast rules. Suffice it to say, when in doubt, run a larger-gauge wire.
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Getting power to the component however is only half the battle. Once there, the current needs to pass through the load and make its way back to the source (the negative terminal on the battery) to complete the electrical circuit. That’s where the ground wire comes into play. Every component on your vehicle has a ground circuit, but some are more obvious than others. Many have a separate ground wire that will connect to either the steel body or chassis or directly back to the battery itself. Others may use a point of contact (housing, mounting screw, and so on) that connect the ground side of the circuit to the body/chassis.
Tips For Chassis Grounds
Regardless of how this circuit may be connected, they all need to route back to the battery without interruption. This is why it’s imperative to have clean grounding straps between the battery/frame, frame/body, frame/engine, and so on. In fact, it is even better to run a complete grounded circuit that all the components can attach to that doesn’t require a perfect bond between an eyelet connector and a painted/powder coated chassis, for example. As we mentioned earlier, a number of modern components can be very sensitive to proper ground connections, especially when it comes to EFI sensors and other precision equipment, making the case for a good ground even more important.
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The foundation for that foolproof charging system comes down to a few simple points. Size the wire correctly and make clean, secure connections, including the grounding circuit. Do this and you should never find yourself stranded, at least not for lack of trying! MR
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