6 Ways to Manage and Protect Dual Voltage Systems

Dual voltage systems are typically found in work vehicles, utility vehicles and other specialty vehicles that have many electrically powered accessories. When the voltage required to power a motor significantly differs from that needed for the auxiliary devices, a dual voltage setup enables the proper distribution of current. 

Without proper support and management, however, dual voltage systems can encounter a range of issues including excessive current overload and rapid battery discharge. In this article we’ll explore six commonly used methods of managing power and safeguarding battery life in dual voltage systems.

1: DC to DC Converters  

DC to DC converters convert current from one voltage to another. Some convert from a higher to a lower voltage, while others convert from a lower to a higher voltage. 

DC to DC converters are ideal for situations that utilize a single power source to power numerous devices with varying voltage requirements. With the help of a DC-DC converter, each powered device can receive a specific voltage while still using power from a single source. 

One common application is in electric utility vehicles and mobile equipment. These vehicles are equipped with high-voltage traction packs, typically 48 volts or higher, to power the motor. However, their auxiliary systems, such as headlights, radios, communication accessories, computers, wipers, and tailgates, operate on a 12-volt power supply. To safely provide power to these accessories, the 48-volt motor power needs to be converted down to 12 volts, a task efficiently performed by a DC to DC converter such as the Eaton Sure Power 48VDC to 12VDC Converter, shown at right.

2: Battery Separators

Battery separators act like switches for directing electrical current between a primary and auxiliary battery bank, managing charging and protecting batteries from draining. Separators are used in a variety of applications such as recreational vehicles, boats, emergency vehicles, construction equipment, large trucks, and off-road vehicles.

Battery separators ensure efficient charging by directing power to the primary battery first and then the auxiliary batteries. When you start the engine, the separator monitors voltage levels in both the main and auxiliary batteries. If the primary battery lacks enough voltage to start the engine, the separator allows current from the auxiliary battery to assist. 

If power usage from either battery bank reduces the overall voltage below a critical level, the separator disconnects the at risk banks to prevent damage. Unlike battery isolators, separators allow current to flow in both directions, enabling the auxiliary battery to recharge from the primary alternator or another power source. 

Battery separators have limitations, such as being subject to parasitic loads. Learn more here.

3: Battery Isolators

A battery isolator prevents the primary battery from being drained by other loads in the charging system, while allowing the alternator to help charge it. The battery isolator stops a fully charged main battery from transmitting current to a partially charged auxiliary battery by utilizing internal diodes to allow current to travel only in one direction.

Current flows from the alternator to both batteries but cannot flow from the vehicle’s battery to loads in the vehicle. The same is true in reverse: Should you leave the vehicle headlights on, the vehicle’s main battery will not get drained. Because each battery is segregated and works as a separate power source in this configuration, the main battery can be used sparingly for starting and other crucial operations. According to its own threshold, each battery obtains the quantity of charge it requires during charging. 

By using an isolator, you can operate equipment in a trailer or RV without having to remember to unplug it from the main power supply of the vehicle. The power of the vehicle powers every piece of equipment while the engine is running; the auxiliary battery powers the trailer equipment while the engine is shut off. 

A battery isolator has the benefit of requiring no power while it's not in use, compared to a battery separator which uses some power even when not in use. Learn more about the differences between battery isolators and battery separators here.  

4: Automatic Charging Relays

Imagine you have two batteries on your boat or RV: a starter battery for the engine and a deep-cycle battery for powering various onboard equipment such as lights and appliances. You want to charge both batteries while ensuring that the starter battery gets priority to always start your engine. A DC Automatic Charging Relay (ACR) can help accomplish this. 

During charging, the ACR engages an internal relay to connect the two batteries in parallel, allowing them to share the charging current. The ACR ensures that the starter battery receives most of the  charging current until it reaches a preset voltage level or charge state. Once the starter battery is charged, the ACR starts directing more of the charging current to the auxiliary battery and continues to balance the charge between the two batteries as needed.

When the engine is turned off or the charging source is no longer active, the ACR disconnects the batteries, ensuring that the auxiliary battery doesn't discharge into the starter battery when the engine is not running.

ACRs are commonly used on boats, RVs, trucks and off-road vehicles with separate starter and auxiliary batteries, ensuring that the vehicle can start reliably and that auxiliary batteries are charged for lights, appliances, and other amenities.

ACRs can also be used in off-grid solar setups with multiple battery banks to optimize charging from solar panels, preventing overcharging and ensuring efficient use of stored energy. 

5: Battery Equalizers 

A battery equalizer is used to balance the charge and voltage levels among individual batteries in a battery bank. This is especially important in systems where multiple batteries are connected in series or parallel, such as in solar power setups, backup power systems, or electric vehicles. Other common applications include golf carts, forklifts, and off-grid remote power installations where batteries are the primary source of power.

Imagine you have a set of several batteries connected in a series or parallel configuration. Over time, due to differences in battery age, capacity, or performance, some batteries may charge or discharge faster than others. This can result in an imbalance in voltage and state of charge among the batteries, which can lead to reduced overall battery bank efficiency and lifespan. 

A battery equalizer actively redistributes electrical energy among the batteries, continuously monitoring the voltage of each battery within the bank. When an imbalance is detected, the equalizer channels a small amount of current from the higher voltage batteries to the lower voltage ones, equalizing the voltage levels among all the batteries. 

6: Auxiliary Battery Switches

Solid-state auxiliary switches are another option for managing the flow of electrical current in DC dual voltage systems. They are typically found in applications such as industrial machinery, power distribution, and control systems. 

Imagine you have a large industrial machine that operates on two different voltage levels for different tasks—a high voltage for heavy-duty tasks and a lower voltage for precision control. The machine's control system needs to switch between these voltages rapidly and efficiently. A solid-state auxiliary switch is ideal for this situation, handling both high and low voltages with precision.

When the machine needs to perform tasks requiring precise control, the solid-state switch smoothly transitions to the lower voltage, allowing for accurate and delicate movements. When heavy-duty tasks are in order, the switch transitions back to the higher voltage.

Solid-state switches are very reliable and require little maintenance because, unlike mechanical switches, they don't have mechanical parts that can wear out or fail.

Conclusion

In summary, when using a dual battery system there are many ways to ensure power and protect batteries from draining, depending on the configuration of the batteries and the power needs required by the vehicle and its accessories. Each battery management technology has its unique strengths. For more information, contact Waytek or see all our battery management solutions on our website.