In this guide, I’ll show you how to connect a charge controller to a battery in JUST 3 steps.
Soon you’ll have them both wired together like this:
To help you out, I’ve made a wiring diagram and step-by-step videos.
Let’s get started!
Materials & Tools
- Solar charge controller
- Battery cables (with terminal connectors on one end and stripped at the other)
- Wire connector
- Fuse holder with fuse
- Wire crimper
- Heat gun
Step 1: Connect the Fuse to the Positive Battery Cable
Note: These installation instructions should not supersede those in your charge controller’s or battery’s manual. Where these instructions differ from your manual’s, follow your manual!
Check out the wiring diagram to see how to connect a battery to a charge controller:
As you can see, it’s recommended that you place a fuse between the battery and charge controller on the positive battery cable. (Use our fuse calculator to choose the right fuse size for your system.)
So that’s where will start:
Place the fuse inside the fuse holder. Connect the fuse holder to the positive battery cable by crimping the wires together with your wire connector of choice. (I used a butt splice connector.) Shrink wrap the connector with a heat gun or heat source.
Give your connection a little tug to make sure it’s good.
First step complete!
Step 2: Connect the Battery Cables to the Charge Controller
Connect both positive and negative battery cables to their respective battery terminals on your solar charge controller. (You charge controller should have the battery terminals labeled with a battery icon or something like “BATT.”)
To connect them, insert the stripped end and screw the terminal shut.
Once again, give the connections a little tug to make sure they hold.
Second step complete! We’re cruising right along here.
Step 3: Connect the Battery Cables to the Battery
Connect the negative battery cable to the negative battery terminal and the positive cable to the positive terminal.
Your charge controller should turn on or light up when you do this. For example, my Renogy Wanderer controller has a light that turns on when the battery and charge controller are properly connected.
And that’s all there is to it!
Now you know how to connect a charge controller to a battery!
Connect your solar panel to the charge controller. (It’s even easier if you ask me.)
Once you do that, your solar panel and battery will be properly connected. You’ll then be ready to add lights, an inverter, and other loads.
And that’s where the fun REALLY begins. 😁
Charge Controller to Battery Wiring FAQ
1. What battery cables do I need to connect my charge controller and battery?
You need two battery cables — one for positive and one for negative — that are stripped at one end so they can be connected to the charge controller.
The should both have the correct terminal connectors on the other end for connecting to your battery’s terminals. For example, the battery I used in this guide calls for 1/4″ ring terminals.
Like I went over in Step 1, safety best practices recommend connecting a fuse to the positive battery cable.
2. What wire size should my battery cables be?
Consider the following factors when sizing your wire:
- Current flow in amps. Pick a wire gauge that is big enough to carry the amount of current (in amps) that will be flowing through your system. A wire size chart is helpful here.
- Charge controller terminals. Some charge controllers have small terminals that won’t accept wire thicker than a certain gauge. Check to see if compatible wire gauges are listed in your charge controller’s manual. If not, you may have to test different sizes of wire to see if they fit.
Tip: Many DIY solar power enthusiasts over-gauge their battery cables to limit energy losses and minimize the chance of fire.
3. Why isn’t my charge controller lighting up/turning on when I connect my battery?
Double check all your connections to make sure that none are loose. If you find a loose connection, tighten it and see if that fixes the problem.
Check the installation instructions in your charge controller’s manual. Make sure you’ve correctly followed all of the steps. Also check to see if you need to connect your solar panel before your charge controller turns on.
If nothing works, your battery may be dead or your charge controller may be damaged. 😕