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Wiring Switches in Parallel

Our Infinitybox system is the most powerful and flexible wiring harness available in the market. Our MASTERCELL inputs are flexible and adaptable for practically any application. A customer just asked this question and we thought that it was a great way to show off the flexibility of the MASTERCELL inputs. The customer is wiring the power window switches in his car. He wanted to know if there was a way to wire a parallel switch that would control all 4 windows at the same time. The answer is “yes” and this blog post will show you how to do it.

Our MASTERCELL inputs work by getting connected to ground. This link will take you to an older blog post that goes through the details of how the inputs work and how to connect a switch to them. Since the inputs work by a ground trigger, this gives you a lot of flexibility with your switches.

This picture shows you how to wire in a parallel switch to control multiple inputs simultaneously.

Picture of a wiring diagram showing how to wire two Infinitybox MASTERCELL inputs in parallel

Picture of a wiring diagram showing how to wire two Infinitybox MASTERCELL inputs in parallel

In this example, we’re showing two switches that control the driver’s and passenger’s windows. For the sake of clarity, we’re only showing the front windows and we’re only showing the down action. These switches are labeled Driver Down and Passenger Down in the wiring diagram. You are going to follow the wire colors from your configuration sheet to wire the switches and the power wires that go to the window regulator motors.

To wire in the parallel “master” switch, you are going to connect the MASTERCELL inputs for the Driver’s and Passenger’s switch together and bring them to the parallel switch. The important thing here is that you need to put a diode on each of the wires from the Driver’s and Passenger’s switch. These diodes are electrical check valves. They only let current flow in one direction. They block the flow of current in the other direction. Without these diodes, both the MASTERCELL inputs would be connected together at the parallel switch. They would both turn on with either switch. The diodes electrically isolate the two MASTERCELL inputs so they are operate independently from the individual switches but work together from the parallel switch.

You can source these diodes anywhere. We recommend a 1N4001 diode. These can be purchased easily from Amazon or other on-line retailers. The orientation of the diodes critical. This will not work correctly if they are installed backwards. Note the orientation of the diode symbol in the wiring diagram above. The line on the diode symbol corresponds to the silver line on the case of the diode. Look at the picture below.

Example of a simple diode

Example of a simple diode

We only show the down action for the power windows in this diagram. We also only show 2 window switches. You can join all 4 inputs together through diodes if you want to control your front and rear windows from a single parallel switch. You can also repeat this for the up action of your power windows.

This same approach can be used for other switches like your lighting. We posted a wiring diagram a while ago showing you how to wire your head lights and parking lights from a single switch using a similar arrangement. You can view that blog post by clicking this link.

Click on this link to download a PDF version of this wiring diagram.

Click on this link to contact our technical support team with any additional questions about wiring your car or truck with our Infinitybox system.

 

Picture of a Cole-Hersee/Littelfuse Battery Isolator

Battery Isolator

Our customers continue to add electrical content to their cars and trucks.  The more electronics they add, the more current they consume.  This is especially true when you are adding powerful stereo systems with sub-woofers and high-wattage amplifiers.  A lot of our customers will add multiple batteries to their electrical systems to increase the available power.  To add multiple batteries safely and get the most reliability out of them, we always recommend adding a battery isolator between them to that they charge and discharge safely.  This post is going to go through the details of battery isolators and why they are critical to multiple battery systems.

In most cases, you want to have a battery in your car or truck that powers all of the main functions.  These functions include your ignition, starter, lighting, fans, fuel pumps, horn and turn signals.  You also may want to add a second battery just to power the high-wattage demand of your stereo.  This second battery would power the amp and sub-woofer.  You may also want this second battery to power any other A/V equipment like TV’s and gaming consoles.  This way you can take your car to a show or take it tailgating, use your stereo and not risk running down the main battery that starts the car.  The problem is that in some cases, two batteries wired together can cause problems.  If one battery is weaker than the other, it can rob charge from the stronger battery.  This picture shows how this happens.

Diagram showing the issue of using two batteries in parallel without a battery isolator.

Diagram showing the issue of using two batteries in parallel without a battery isolator.

A weaker battery can drain a healthy charged battery in your vehicle.

The simple solution is to add a battery isolator between the two batteries.  Examples of good battery isolators are manufactured by Littelfuse .  These can be purchased at companies like Del City and Waytek Wire.  This picture shows the battery isolator wired between two batteries.

Diagram showing how a battery isolator works with two batteries

Diagram showing how a battery isolator works with two batteries

The battery isolator stops current from flowing between the two batteries while allowing both to charge safely from the alternator.  This picture shows how most battery isolators are wired between the alternator and the bank of batteries.

Schematic for wiring dual batteries with a battery isolator

Schematic for wiring dual batteries with a battery isolator

When you’re using our Infinitybox system, that is going to get powered from the primary vehicle wiring.  All of your accessories like amps, sub-woofers, inverters and winches will get their 12-volt power from the second battery.  If the accessories drain the second battery, this drain will not pull down the primary battery.

Click this link to contact our technical support team with questions or comments about this post.