Victron Energy Autotransformer

Autotransformer is a useful device from a third party company Victron Energy.

Reasons for using an Autotransfomer:

1. Two DELTA Pros and exrra batteries connected to a Double Voltage Hub are not depleting equally
2. Loads on each 120v split phase are not balanced
3. You require 240 volts while using only one Delta Pro
4. You have two DELTA Pros and want to have double the solar input capacity (1,600 watts x 2) and only output 120 volts

My Autotransformer Setup

I use an Autotransfomer to address the #1 and #2 reasons listed above as without the Autotransformer, my Double Voltage Hub shuts off when either DELTA Pro runs out of power. With the Autotransformer, despite uneven loads, the Autotransformer draws from the two DELTA Pros evenly giving me a longer overall runtimes.

The wiring is straightforward as the Autotransformer sits inline between the 30 amp twist-lock outlet of the Double Voltage Hub and my house inlet. I actually purchased a 10 foot L14-30 twist lock cable and cut it in the middle to get two 5 foot cords. I added a WAGO connector to tie the three green ground wires between the input, output, and Autotransformer. The Autotransformer only takes the two hot wires as input so neutral is not connected and capped with a wire nut. The two hots and one neutral wires along with ground are connected to the output cable that feeds my house inlet

Caveat: When connected to a Double Voltage Hub, all of the front outlets on BOTH DELTA Pros are disabled. To access 120v power near my setup without having to go through the manual transfer switch to my household circuits I added an L14-30 splitter and an L14-30P to four 5-20R outlet adapter to provide a standard household outlets near my big shelf of EcoFlow gear. Pictured below is a space heater plugged into this setup. The splitter sits between the green autotransformer output and my house inlet giving me a place to tap into the the 240v split phase as two 120v circuits with built-in breakers (links below).

Thank You Tre!

I want to give a HUGE shout out and "Thank you" to Tre Nt for forging the path for us on this topic as he blazed the trail for me personally. Here is Tre's original Facebook post on the Auto transformer.