Choosing the right DC wire for your van.

Current flows through electronics is converted to energy and measured in amps.

Since a wire that is too small can overheat and eventually catch fire its important that you choose the correct wire.

How to use the chart

  • Locate the amps: Most electronic devices include a ratings chart either as a label on the device or a document accompanying the device.
  • Measuring how long: Measure the distance from the source (battery) to the device then multiply by 2. The total length of the measurement is called the circuit round-trip.
  • Determine the allowable voltage drop: Voltage drop is the decrease of electrical potential across connectors. Voltage drop in your home, for example, is when you turn on a fan and the lights flicker. Electronic devices (such as tablets, cell phone, laptops are) sensitive to voltage drops and are considered critical devices.


  • You have a refrigerator rated at 80 amps and determine it is not a critical device.
  • Locate the Non-critical column on the chart.
  • You’ve measure the distance from the battery and the electronic device and determine the distance to be 25 feet.
  • To get the round-trip total multiply by 2. (25 x 2 = 50)
  • From the non-critical column slide your finger down on the chart until you locate 50 ft.
  • Slide your finger to the right and locate 80A (amps).
  • 80 amps at 50 feet require 4 AWG wire.

Questions and Answers

Q: Is it okay to use a wire that is larger than needed?

A: A wire too large for the circuit is not a problem; it costs more. But you should be fine.

Q: How warm can a wire get before I should be concerned?

A: A warm wire indicates that the load (current) flowing through the wire is higher than the wire is rated for and could potentially melt or weaken the sleeve preventing and protecting the circuit from shorting out on the other wire causing a fire.

Another note:

If you plan to run more than one device on a wire. Add the amps together to determine the correct wire size.

Q: Can I safely hook up a tinkle charger to my batteries.

A: Yes it’s okay to use a trickle charger. You don’t want to over charge your batteries so make sure you have a device to warn you or a trickle charger that will not over charge your batteries by shutting off. I have one for my motorcycle, that shuts off and on when needed.

Overcharging a battery will heat the battery, cause swelling and smell like rotten eggs.

Q: How many batteries can I add.

A: You can charge as many batteries together as you like but all of the batteries must be the same amps. You cannot mix 35ah batteries with smaller or large amps.

You also do not want to mix battery types. If you purchased acid batteries, then use all acid batteries.