What Gauge Wire To Connect 12v Batteries?

Choosing the right gauge wire in a system is essential as an oversized wire may cause significant voltage drop, while an undersized one causes accidents. Are you trying to determine the correct size of interconnecting cables between batteries? Or, thinking what gauge wire to connect 12v batteries?

Well, 12v batteries store and provide a variety of power. If you connect batteries in series, the wire should be matching the maximum amperage delivery of any of the batteries. This is because, voltage increases in series, not amperage. If connected in parallel, the exact opposite happens.

Copper wires are sized utilizing a gauge scale known as American Wire Gauge (AWG). Depending upon the total amperage, the gauge number differs.

This article will discuss it in brief.

What Is A Battery Bank?

A battery bank is a result of joining two or more batteries together either in series or parallel for a specific application. The battery bank is made so that you can increase the overall voltage, amperage, or both.

The best example of a battery bank would be its application in a PV system. A battery bank is produced to store electricity that is generated by solar panels to use anytime you want.

The battery bank also serves as an energy center that delivers power or electricity when the solar panels are not in working conditions (dark or bad weather).

What Gauge Wire to Connect 12v Batteries?

You’ve seen amps and volts vary depending upon the circuitry connection. Make sure the batteries you’re connecting are of the same capacity and voltage rating.  

There are two methods to determine what gauge wire to connect 12-volt batteries. The first one is the most used one where wire gauge is determined using a chart named the American Wire Gauge (AWG) system chart.

The AWG is a system that numerically calculates the battery interconnect cable size of the wires that starts with the highest number for the smallest size.

Battery cable size chart:

AmperageCable Size (AWG – gauge)
0-516161616141212
5-1016161412101010
10-1514141210108814
15-2014121210866
20-251210108666
25-301010108664
30-408886644
40-508866442
50-606664422
60-706644221/0
70-804444221/0
80-90444221/01/0
90-100222221/01/0
100-12022221/01/02/0
120-1501/01/01/01/01/02/04/0
150-2002/02/02/02/02/04/04/0
Length in Ft0-44-77-1010-1515-2020-2525-30

When you know both the amperage and cable length, you can easily find out what size of battery cable to use from the chart. The chart is widely accepted to choose the correct size wire gauge for connecting batteries. The lower the current and the shorted the batteries are, the smaller cables you require.

If you have a battery bank that is capable to produce 25 amps, you should use 12 AWG cables to make sure a safe connection is produced. The chart is made for 12v batteries. If you have 24v batteries, you only need to double the gauge cable size that is given here.

You can also use battery cable size calculator to get the right cable size.

What Gauge Wire To Connect two 12v Batteries?

You need to determine what amps of current flow through interconnecting cables of the battery bank consisting of the two 12v batteries. The flow of current or amperage and voltage depends on the battery configuration whether the connection of the batteries in parallel vs series.  

Batteries Connected in Series

Wiring batteries in series will increase the voltage of the battery bank, while keeps the amperage rating (amp-hour) the same. For example, if you connect to 6v batteries in series, the bank will produce 12 volts in a total while have to same 10AH rating.

To connect 12v battery linking cables in series, you need to connect the negative terminal jumper cable of a battery to the positive terminal of the second battery. Again, connect the positive terminal of the first battery to the negative terminal of the second battery.

Batteries Connected in Parallel

When you put a parallel connection between two or more batteries, the overall current rating or amp-hour will increase but the voltage stays the same. For example, when you connect two 6v parallel batteries, you still will get 6 volts from the bank, while the amps will increase to 20AH.

To connect two batteries in parallel, you need to connect both the positive terminals together with jumper cables and both negative terminals as well.

One thing to mention is that, as the amperage of the battery bank increases in the parallel battery connection, you need to put a heavier-duty cable to make sure it isn’t burning out.

Note: Don’t cross an open positive and open negative terminal with each other while connecting batteries. It’ll cause a short circuit which may damage the batteries and also sometimes injures you.  

Final Verdict

So, now you know what gauge wore to connect 12v batteries.

If you have a panel to make by connecting multiple 12v batteries, you must need to determine the right gauge wire to connect the batteries. Otherwise, you won’t get the expected voltage from the bank whenever needed or the cable may burn out due to excessive pressure.

That’s why choosing the right wire size is really important. I hope that you will be able to pick up the right gauge wire for your 12v batteries from now.

Thanks for reading the article.

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