Using Redarc Battery Isolator on Boat with Two Engines and Batteries

Updated 06/03/2019 | Published 05/31/2019

Question:

I am installing a Redarc dc to dc charger in my boat. My problem is that my boat has two, 5.7 liter engines that each have a starter battery. The starter batteries are independent from each other and at times when Im fishing I only run one engine at a time as I alternate engines every hour to maintain the same amount of run time on them. When I am travelling, I run both engines. Because both starter batteries are independent from each other, is there a solenoid configuration that would automatically switch between the batteries to draw from the one that is in use and only use one battery when both engines are being run? If I connected the starting batteries in a parallel configuration, would it damage the alternators on my engines as they would both be trying to charge at the same time? I do plan on installing solar panels at a later date.

asked by: Bud K

Expert Reply:

This is a really good question. I spoke with my contact at Redarc and this is what they sent me:

There are a few variables to the application but realistically keeping each engine with its own starting battery is recommended. The reason behind this is if there was an issue with one engine, you will always be able to run the other.

My assumption is that your customer is wanting to run auxiliary equipment. If this is the case then another battery or battery bank is required and then run the BCDC off your main engine battery. Please note that the BCDC will only operate when the main engine is running.

expert reply by: Jameson C