Ask PYS: Power

Automatic Combiner Relay or Voltage Sense Relay, on Dec 01, 2016 asked:

Hi Jeff, I met you the other day while you were performing an Electrical Audit on a friend’s boat. You mentioned a product that allows you to direct excess power from one battery to another when charging. What is this called and how hard is it to install. – Rob



The device I was referring to was an Automatic Combiner Relay (ACR) from Bluesea, BEP also makes a similar product called the Voltage Sense Relay (VSR). You connect an ACR/VSR to two battery banks, for instance engine and house batteries, and whenever there is a charging voltage present on either battery the relay is activated and the batteries are in parallel. Once the charging voltage is removed (i.e. 12.8 VDC) the batteries are separated and are each on their own.

Remember to fuse both sides of the circuit at each respective battery bank. Install time will vary depending on distance between batteries, as a starting point, I would budget at least one hour to install.  - Jeff