Recharging House Battery with Two Outboards

Question:

Hi Jeff, I hope you're well. I recently discovered your website and YouTube channel and have become fascinated by your informative videos. I would be grateful if you would kindly spare a minute to give me some advice.  I have a twin outboard 36ft cruiser. Each engine has it's own starter battery. In addition, I have a house battery bank made up of 2 batteries. The only source of charge my house batteries have is shore power. All batteries are Optima Bluetops.

I have looked at both VSRs and FET isolators and cannot decide which would be the best solution for my boat. Could you please advise what you think would be the best option?  If a FET isolator is the best choice could I run both alternators into the same one, or would I need a separate isolator for each engine. Thanks again in advance and do keep up the good work with your videos.  - Mohsin

Answer:

Hi Mohsin, with outboard engines the best way to share a charging voltage to a house battery is to install a battery combiner (e.g. VSR or ACR) between the engine and house batteries. Because you have two engines, you’ll need two VSRs, so that each engine charges the house battery.  - Jeff