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A charge controller ensures the battery receives the maximum charge without overloading. However some controllers also have a load output, but what does it do? If you’re running a solar system it’s essential you understand what each device can do, including the solar controller.
Charge Controller Load Output Explained
Also called a +load output terminal, its main purpose is to manage the load and maintain the battery terminal voltage. Load output features vary, but it’s mostly used to load lighting. An on/off toggle switch and timer settings provide additional controls. More advanced controllers have additional features, but the on/off is the most important.
These controls make it easy to manage lights. With these you can turn the fixtures on and off automatically or manually at specific time periods. If a battery reaches a certain discharge rate, i.e. 11V, the load output will be turned off. This feature keeps the battery from overcharging. This gets turned on after the battery gets charged to 12.5V.
What is the Maximum Terminal Load?
The limit is set by the regulator rating, like 20A. It isn’t a good idea to link a controller output to an inverter as the current pull will be too much, especially with a powerful inverter. Doing so could lead to severe malfunction, so you should check the controller product guide for the maximum load. Ideally the value should not be close to the maximum to give the device some space.
Why Do I Need a Load Connection to a Charge Controller?
Most people think of charge controllers as battery regulators, and that’s understandable. But load terminals allow solar controllers to do more. Depending on the design, you can configure it to run small devices in different ways.
You can use the load output to set up several lights in your garage, shed, basement or any outdoor area. You can do this in homes and business centers as well. Connect 3-4 LED bulbs on the load output and you’ve got a decent lighting setup, ideal for storage rooms, workshops or a DIY testing center.
Make certain the load output does not go beyond the controller rating limit. If it does the system could break down and blow a fuse. You’re not limited to lights as pumps, motors and other electronics can be hooked up to the load. As long as the total doesn’t surpass the controller rating, the system is all right.
For RV owners, you probably won’t need to use the load output. If you have a solar panel installed in your RV, it will use the load built into the system. Most solar ready RVs and solar panel kits have this feature pre-configured so you don’t have to use the controller load output terminal. But it can still be used in DC only configurations for specific setups.
What is Charge Controller Low Voltage Disconnect (LVD)?
The LVD is the same thing as the controller load. Whether it is called a load or LVD the purpose is the same. While designed mainly for light as mentioned, you may use this for low powered appliances. Because it is low voltage disconnect, the terminals go off. This also keeps the battery from getting completely drained.
We must emphasize that the controller load can and should only be used for low watt devices and appliances. Connecting it to a high powered appliance or inverter will damage the controller and the inverter. Check your controller setup guide for specific details on load limitations. Knowing how this works can prevent a battery connected to a controller from draining overnight.
Can a Solar System Run Without a Charge Controller Load Input?
Yes, most systems run fine without an LVD or a load terminal. As we stated RVs and motorhome don’t need it, and solar powered homes will run without too. Since the controller rating sets the load limit, this can be from 6-60A.
The bottom line is you’ll only use the load output for small appliances, devices and inverters. Forget about running a 5000W inverter here, as only the lowest powered inverter is possible. Some load inputs can handle load control relay and remote operations for cameras, but these are specialized products. Knowing the load output is especially important if you have a 1000 watt solar panel or larger array.
If you have no plans to run small appliances / devices / tools on the charge controller, then this feature isn’t necessary. Though as we pointed out, it can come in handy when you want to use low powered lights in various locations. That’s one of the reasons why load output is becoming common especially in MPPT charge controllers.
MPPT Charge Controller Load Output
MPPT charge controller load outputs run similarly to other controllers. Special controls are built in that enable you to manually or automatically load applications. It’s often used in glamping because it makes load switching easy.
An MPPT controller load is easy to disconnect in case the system is overloaded or running low in power. Some of these controllers can measure the current in the load output, which leads to more accurate power readings Most power monitoring systems are for AC or all in one systems. But if you have a DC only camping setup, this can be useful in energy management. More advanced MPPT controller load inputs have Bluetooth enabled monitoring built in.
What are Charge Controller Sense Terminals?
Some charge controllers are equipped with sense terminals, which produce tiny amounts of current. The sense terminal checks the battery voltage and determines if it is similar to what the controller produces. If the voltage goes down, it will boost the output so the two match.
Sense terminals are only necessary if there is a long cable between the battery and charge controller. These are linked to the controller terminals and set on the terminals used by the battery charge wires. This is not standard in charge controllers so don’t be surprised if yours doesn’t have it.
A charge controller performs several important functions in a solar power system. As someone who owns a solar system you need to be aware of what it can and cannot do. Understanding what the controller load output is for can make a huge difference in terms of the system’s performance.