The TBCM-40A Trailer Battery Charging Module senses the alternator charge voltage of the towing vehicle and sends charge current to the trailer battery. When the vehicle is not running, the TBCM-40A disconnects the trailer battery from the vehicle’s charge wire to prevent having two dead batteries. The TBCM-40A works with existing 12 volt trailer wiring, including on-board 110 volts AC chargers, and handles most towing vehicle alternators.
The TBCM-40A is mounted in the trailer battery box or engine compartment and only requires three wires for connection. The TBCM-40A does not have a .6 volt drop to sulfate your battery like RV type isolators.
For more information go to “other details” for the product sheet.
Dimensions: W: 1.20” x H: 1.2" x D: 3.20"
Posted by Mark R Wespi on May 4th 2019
I have been using this module to charge our trailer battery while on the road. Works as stated, very sleek, easy to install and makes a great top up for our battery while driving.
Posted by Martin Lappin on Aug 30th 2018
Installation was simple enough with the most time being spent finding the correct wires in the power distribution box on my truck.
Posted by Dan Ee. on Jul 4th 2017
This is a well made, easy to install product. It works as described and gives me piece of mind to know my trailer system is automatically disconnected when the tow vehicle enigine is off. I will recommend this to my friends.
Posted by Kent Madison on Jan 4th 2017
Installed this unit on a tilt bed trailer with a 12 volt battery. It works great and keep the battery fully charged and protects the charging circuit on the tow rig. It would be nice to include some double sided tape to use during install.