Introduce the battery isolator function and easy installation method



Battery isolator is a battery connection device that connects two or more sets of batteries together, and multiple batteries can be charged together when charging, but the batteries are discharged separately and do not affect each other when discharging. Today, this article will explain battery isolator in detail.


1. What is a battery isolator

In general, battery isolator is a relatively advanced technology. It is a device used to protect battery system, save energy, and prevent the car generator from overloading and excessive current when the car is started. Its function is to obtain electric energy from battery pack when the car starts, to ensure the stable operation of the generator, so as to protect battery pack and save power in long-term operation.

One of the main reasons to use battery isolator in RVs is to isolate the car's starting battery from the living battery. This ensures that power is not drawn from the starting battery when used in parking mode, resulting in the starting battery losing power and being unable to start the car. And when using the motor in driving mode, the starting battery and the live battery can be charged at the same time.

Another reason is that the purpose of the battery is not to start the vehicle, so the instantaneous high car battery voltage and current may have a bad effect on it. A battery isolator is a chemically formulated electronic component equipped with a specific structure to achieve voltage isolation between two or more batteries and the function of protecting battery pack charging system when battery voltage changes or falls.

2. The operation principle of the battery isolator

When the engine starts, the generator itself charges the starting battery, and when the voltage reaches about 13.4V, the intelligent manager turns on the secondary battery, and the two batteries are connected in parallel, so that the two batteries can be charged at the same time.

When the engine stops, the electrical equipment slowly consumes power. When the battery voltage drops to about 12.8V, the intelligent manager is disconnected, and the two batteries are not connected in parallel, so that the power of the starting battery will not be consumed.

The operation principle of the battery isolator


If the starting battery power is insufficient, you can press and hold the emergency switch on the driver's platform, so that the intelligent manager can manually force the parallel auxiliary battery to start the engine, release the emergency switch after starting, and the intelligent manager can resume the automatic working state.

3. The function of the battery isolator

● Effectively manage the voltage

Compared to ordinary car batteries, battery isolator can effectively manage the voltage of car batteries. If the battery in the car is too large or too small, this will easily cause the car battery to fail, causing the vehicle to not start. battery isolator can isolate battery terminals, effectively limit battery voltage flow, and effectively protect batteries from harm.

● Higher protection function

In addition, battery isolator can connect different battery systems, while the battery isolator has a protection function, which can play a limiting role when battery voltage is too low or too high, so that battery system can work normally. In addition, it can also provide automatic charging function. Car battery charging systems can automatically charge by controlling the battery, without the need for someone to check regularly next to the battery, saving manpower and material resources, and improving the operating efficiency of the system.

● Reliable insurance function

Moreover, the battery isolator can also be used as an insurance function, and the change in the battery provides better safety for the vehicle, which can avoid overloading the car battery, thus effectively preventing the vehicle from fire extinguishing, parking, power loss and other phenomena. Finally, battery isolator can prevent the reversal of current, and when the battery is installed on the vehicle, battery isolator can prevent current from flowing back from the vehicle to battery, and also from the vehicle to battery.

The function of the battery isolator


● Saving electric system

Last, the cable can be prevented from being reversed, effectively protecting battery system. The main function of the battery isolator is to charge the two batteries at the same time and use them separately, and the battery capacity can be inconsistent.

● Specifically, battery isolation in the 12v battery RV system is:

When charging (when the car generator is working), connect the main and auxiliary batteries in parallel and charge them together. Generally, the main battery is charged first, and after the main battery is fully charged, the secondary battery is automatically charged without affecting the power supply of electrical equipment.

When not charged or discharged, (the car generator is not working), battery isolator will automatically isolate the main and auxiliary two sets of batteries, when the secondary battery is discharged, the main battery does not discharge, do not worry about lack of power and can not start the engine. When the main battery is damaged or loses power, there is an emergency auxiliary switch, which can borrow the power of the secondary battery to start the car.

The principle of this emergency auxiliary switch is actually that when it is not charged or discharged (under normal circumstances, the main and auxiliary batteries are isolated at this time), the two groups of main and auxiliary batteries are forced to be connected in parallel, and the secondary battery is used as the starting battery.

4. Why do I need to install a battery isolator

On each RV, there was originally a battery, which we called the main battery. But if you want to add more electrical equipment to the car, obviously one battery is not enough. Moreover, it is easy to drain the original battery, so that the car cannot be started. At this time, we need to increase the battery and increase the battery capacity.

Why do I need to install a battery isolator


Some people connect the secondary battery and the main battery directly in parallel, which is also undesirable. The main and secondary batteries are directly connected in parallel, although the total battery capacity is increased. But when the secondary battery is dead, the main battery will charge the secondary battery, and vice versa. This increases power loss and also reduces the service life of both batteries. To solve such a problem, a battery isolator is required.

5. Battery isolator usage environment

Battery isolator has a wide operating temperature range, from minus 50 to 125 degrees, waterproof, shockproof, anti-magnetic, and do not have high environmental requirements. Vehicles equipped with large-capacity electrical equipment are available. It is recommended that when modifying high-power electrical appliances and other high-power external circuits, it is best to use secondary batteries directly.

6. How to choose the right battery isolator

Below, we've listed the most commonly used battery isolator in RVs. Each has its own advantages and disadvantages, so you can choose one that meets your needs according to your needs.

● Manual switch

The easiest way to connect the living battery to the car's generator is to connect the cathode of the starter battery to the cathode of the living battery with a wire, and install a high current switch at a suitable location in the middle of the wire. You can manually turn this switch on or off to control the connection or disconnection of the starter battery from the living battery.

● Conventional relays

Conventional relays are mechanical switches that are turned on using an electrical "signal." After energization, the internal solenoid valve is activated and two internal contacts are connected. Because the two contacts are connected to the cathode of the starter battery and the living battery, they are connected together.

How to choose the right battery isolator


When the engine is turned off, the solenoid valve inside the relay loses current and disconnects the internal connection, so that the starting battery and the living battery are isolated. This is the most complex method of battery isolation because you have to connect signal lines to the relay. For dual battery isolation, you want the relay activated while driving. So the best way is to connect the signal line of the relay to the spare fuse socket in the fuse box.

Before doing it, it is best to measure it with a multimeter to see if there is a voltage of 12V after the engine is started, and whether the voltage is 0V after the engine is turned off. Over time, the internal movable contacts may wear out, resulting in increased resistance and voltage drop. Unless a bypass switch is installed, you will not be able to do battery hookup of starter battery to the living battery in an emergency.

● Voltage Sensitive Relays (VSRs)

It turns on the internal contacts when it detects a high generator output voltage and disconnects when the generator output voltage is low. This is a method that does not require any external signal cables, so it is relatively easy to install.

Voltage sensitive relays are probably the most commonly used isolators in many RV retrofit projects. They are easy to install and relatively reliable compared to other available technologies. But it is essentially a relay, so it has the same drawbacks as the conventional relay above. The price is also higher.

● Diode battery isolator

Diode battery isolator typically has two separate diodes inside. They divide the generator current into two strands, charging the starting battery and the living battery respectively. When the engine is turned off and the charging is stopped, because both batteries are connected to separate diodes, the current cannot flow back by itself.

So the starting battery and the living battery are isolated from each other and not connected to each other. The only problem with using diode battery isolator in RVs is that they can have a significant voltage drop. This means that the charging voltage will never meet requirements of battery, resulting in undercharging.

Specifications for connecting isolator wires


● Specifications for connecting isolator wires

After the battery is deeply discharged, its resistance is relatively low. When powered on, the battery draws a lot of current. Therefore, when installing a battery isolator, it is essential to select the correct wire specifications. The specifications of the selected wires must meet the maximum current that the car generator can provide. If the correct wire specifications are not installed, permanent damage to batteries, battery isolator and other electrical equipment may occur.

In the worst case, it can lead to an electrical fire, with catastrophic consequences. So we need at least 16mm (110A) wire. This should be sufficient for most vehicle alternators. But also note that the starting battery can also act as a power source, and when connected to a living battery, it will try to balance the voltage. If your life battery is severely depleted, then the charging current of the life battery will exceed the output current of the generator.

7. Conclusion

In summary, battery isolator is an important electronic component designed to prevent the inflow of high voltage current into battery system, while managing the battery voltage and protecting battery to prevent battery damage and ensure vehicle safety. The above is the introduction of battery isolator. I hope this will help you when choosing to install battery isolator.


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