Concerned about your multi-battery setup draining each other? A battery isolator can help! It manages current flow in your off-grid system, preventing power drains with a simple switch and stopping batteries from depleting one another. It’s a game-changer for any multi-battery setup. Read on to learn more!
What Is a Battery Isolator?
A battery isolator is an electrical device that splits direct current (DC) from a single power source into multiple branches, ensuring unidirectional current flow to each connected battery. This prevents batteries from draining each other while allowing simultaneous charging. In a dual-battery system, the isolator ensures a weak auxiliary battery does not draw power from a healthy starter battery.
What Is the Purpose of Battery Isolators?
These devices give users greater control over power systems, especially in multi-battery setups where batteries charge or discharge at different times. They help prevent unintended or uneven battery discharge. Many also use battery isolators to disconnect backup batteries.
Where Are Battery Isolators Used?
You’ll often find battery isolators in various setups.
In vehicles like RVs, boats, trucks, and off-road rides, they keep the starter battery separate from auxiliary ones powering accessories like winches or fridges.
In aviation and marine settings, planes and boats use them to ensure backup power is always ready.
Renewable energy systems, such as solar setups and off-grid systems, also rely on isolators to manage their battery banks efficiently.
What Type of Battery Isolator Do I Need?
The battery isolator you need depends on your electrical setup and its intended use. Here are the most common types:
Manual Isolators
If you’re looking to set up a backup battery for electricity, a manual battery isolator is an easy choice. It has a switch that lets you connect or disconnect the backup battery, usually with rotary switches or simple on/off toggles.
However, keep in mind that these won’t prevent your battery from accidentally draining. In this setup, the batteries remain separate unless you need to connect them in an emergency to start the engine.
Relay Based Isolators
To protect your starting battery from the alternator or secondary battery, use a relay-type battery isolator with external control. This is beneficial when the secondary battery exceeds the alternator’s current capacity, drawing excessive power from both batteries. A relay isolator with external control prevents this drain.
Alternatively, a relay-type isolator with an internal voltage cutout can prevent the secondary battery from draining if the starter battery is low.
DC-DC Charge Isolators
A more advanced battery isolator includes charge control, known as DC to DC chargers, which connect two batteries. These units precisely manage the current between batteries and ensure proper charging of a second battery. Customers often use a DC-DC charger with engine battery systems to safely charge lithium batteries without overloading the alternator.
While designed for one-way charging, these units can be re-wired in emergencies to reverse the charge, useful if the starter battery fails. This method provides a better solution than simply jumping the battery.
Diode Battery Isolator
A diode battery isolator is useful for preventing multiple lead-acid batteries from draining each other. Diodes allow current to flow in one direction, enabling batteries to charge from an external source (like solar, an alternator, or shore power) without drawing from one another.
Diode isolators are solid-state devices with two terminals for the batteries and one for a common connection, allowing power to flow to the center post but not backward.
How Are Battery Isolators Rated?
Here are the main specs you should know about:
- Current Capacity: It ranges from 25A to 300A, depending on your usage. For example, small RVs might need around 80A, while industrial trucks could require over 160A.
- Voltage Compatibility: Most can handle either 12V or 24V systems.
- Number of Batteries: You can connect between 2 and 4 batteries with these models. Some even allow you to mix configurations, like having one starter battery and two auxiliary ones.
Do You Need a Battery Isolator for Dual Batteries?
Yes, if:
- Your vehicle has a separate starter battery and auxiliary loads, like camping equipment, that might drain the main battery.
- You want a backup power source to stay charged, just in case.
No, if:
- The batteries are the same and you’re using them together only for quick power boosts, like for your car’s sound system.
Do You Need a Battery Isolator?
In a simple one-battery setup, an isolator may not be necessary. However, in vehicles, RVs, or boats with multiple batteries, it is essential. A battery isolator prevents getting stranded with dead batteries in remote locations.
