What Gauge Wire to Connect Two 12v Batteries In Parallel
Using the correct wiring is vital to any operating system. That includes your RV or travel trailer. Without the right wires connecting anything, you won’t have power and you may have to replace some essential devices. Always be wary of the gauge of the wire before making any connections
The official recommendation may be 4 or 6 gauge wire but for most RVs and travel trailers, 10 gauge is the correct thickness. It is rated for up to 30 amps. Anything thicker than this measurement is done to protect any current drop-off that occurs between the source of power the devices connected to it.
To learn more about this topic, just continue to read our article. It has the information you want to know about so you can make the right connection and not damage your electrical systems. Take a few moments to read up on this important subject.
What Gauge Wire Should be Used With a 12-Volt Battery?
The thickness of the wire depends more on how many amps will be running through them than anything else. The length of the wire may play a role in which wire thickness you use. The following chart shows you number of amps and the wire thickness for those connects up to 4 feet in length:
| Number of amps | Wire gauge |
| 0 to 10 | 16 |
| 10 to 20 | 14 |
| 20 to 25 | 12 |
| 25 to 30 | 10 |
| 30 to 50 | 8 |
| 50 to 70 | 6 |
| 70 to 90 | 4 |
| 90 to 120 | 2 |
| 120 to 150 | 1/0 |
| 150 to 200 | 2/0 |
Also, these figures are for a 12-volt battery system. If you want to hook up 24-volt batteries, then you need to double the figures you see in the above chart.
Can You Wire 2 12-Volt Batteries Together?
Yes, this is possible and it is done all the time. The fact that it can be and is done every day means that it is also a very safe method to use when you need more power. The key to this safety though is to hook up the right gauge wire to the right terminals.
When you connect two 12-volt batteries in parallel, your amperage will increase. That means you need to go to a thicker cable to make the connection safe and not ruin your electrical devices.
When you are making the connection do not go from open positive to open negative as that will cause a short circuit which can harm both you and your batteries.
When you want to make a connection of 2 batteries in a series then your amp rating will remain the same but the number of volts will increase. The connecting wires should go from the negative terminal of the first battery to the positive terminal of the second battery.
The positive terminal of the first battery should connect to the negative terminal of the second battery.
What Gauge Wire To Connect Two 12v Batteries in Parallel
This will be determined by the number of amps flowing through the wires. It will also depend on the length of the wire in parallel. The longer the wire the thicker it has to be. For example, the chart says for wire length up to 4 feet a 30 amp charge requires a 10 gauge wire.
However, when the wire is 10 to 15 feet long, you need an 8 gauge wire; for 15 to 20 feet you will need a 6 gauge wire for the same amount of amps. And on it goes down to up to 30 feet in length which would need a 4 gauge wire to make the connection.
When you make the connection, make sure it is tight, and there are o frays or broken parts in the wire. Watch where you lay the wire as well as you do not want anything to disturb it when it is working.
How do You Wire 12-Volt Batteries in Parallel?
When you wire two 12 volt batteries in parallel, remember that you are not going to increase the voltage. The two or more batteries will always produce 12 volts. As we said earlier, the number of amps will increase and you have to watch the gauge of wire at this time.
10 gauge wire is rated for up to 30 amps. If your parallel system creates more amps than that level, then you have to move up to a thicker gauge wire. When you are making the connection between the two batteries, go positive to positive and negative to negative.
Be careful not to make any connections that will short circuit the system.
12v Parallel Battery Cable
You can find these wires just about anywhere wiring is sold. Your cheapest option may be Amazon. But your local electrical outlets should have enough of a selection at a reasonable price that you do not have to wait for shipping time.
Wiring is not going to be that expensive and should depend on the length you are buying. Some stores may have a minimum amount you can buy but that is okay as it is always good to have some extra wire in storage when you need it.
When you shop at Amazon, many of their wire options already come paired for parallel systems. You just have to select the vendor you want to deal with. However, going to the store and checking it out first hand can save you a lot of hassle and make the purchase simple and easy.
Some Final Words
Making the right connections depends on using the right gauge of wire. The 10 gauge option will work for most RV and travel trailers as long as you are not running more than 30 amps through the system.
Watch the distance though as you may be running longer distances which require thicker wires. You are in control here so make the right choices.
