Auxiliary Current Shunt
Installation and Operating Instructions

#1011, #1014 June 11, 2003
Copyright ©1994 through 2003. All Rights Reserved - Ample Technology


The Auxiliary Current Shunt, is used in conjunction with the Energy Monitor/Controller, H1 to measure current in the negative rail, (negative side) of the system. It can be used with alternators, battery chargers, solar panels and wind generators.

The Auxiliary Shunt works with either 12 or 24 Volt systems.

NOTE: The charge source must not be grounded for the Auxiliary Shunt to measure current. Many alternators are grounded through their case and won't work with the Auxiliary Shunt. An alternator with an isolated ground terminal is required.


The Auxiliary Shunt is a manganin shunt assembly mounted on a plastic base. There are two large terminals, (3/8-16) for the main current and the two sense terminals which can be either 8-32 or 10-32. The shunt is designed to produce 50 millivolts at its rated current, typically 200 Amps.

Signal Names and Functions

Wiring Information

$\bullet$ Use pre-tinned wire :: Over time, corrosion attacks even the best connections. The use of pre-tinned wire will delay the onset of corrosion and is worth the slight price differential.

$\bullet$ Use a twisted pair :: for the wires going to the Energy Monitor/Controller. If a shielded, twisted pair is used, connect the shield only at the shunt end of the cable. The twisted pair wire gauge can be as small as #24 AWG, however, for mechanical strength its always better to use larger wire.

$\bullet$ Wire Size :: Wire gauge callouts on the drawings is only for reference. Always consult a wire table to determine what size is appropriate for your specific system. A wire table can be found in The Ample Power Primer, which can be ordered from an Ample Power dealer, or downloaded from the Ample Power website,

$\bullet$ Prevent Chafe :: Avoid running wires near metal objects, if possible. Always secure wires so that they cannot chafe with vibration.

Wiring Diagram


Troubleshooting Information

$\bullet$ Polarity sensitive :: If the two signal wires to the Energy Monitor/Controller are reversed, the Auxiliary channel will read zero. No damage is done by the mis-wire. If in doubt, swap the two signal wires.

$\bullet$ True Zero :: To test the Energy Monitor/Controller for a zero reading, put both signal wires at the shunt under one lug.

$\bullet$ Dissimiliar Metals :: Brass screws are used to connect the signals wires to the shunt. If one of them is lost, do not subsitute a different metal. An offset voltage will be created which will show up in the Energy Monitor/Controller as a current reading.

Installation and Warranty Support

For questions regarding installation, operation, or warranty service contact PowerTap, Inc. who is the authorized warranty service agent for all Ample Power products. Their phone number is 206-789-4743, and their fax is 206-789-9003.

Email support is available from See also the following websites for more troubleshooting suggestions.

Ample Power products are manufactured by Ample Technology, 2442 NW Market St., #43, Seattle, WA 98107 - USA