Marine Battery Charger Question

Question:

First of all, thanks for the wealth of knowledge that you post on your website. I’m sure it helps many boaters. I have a question regarding a re-battery project on my 42’ cruiser.  I am planning to replace my current batteries (1 ea engine x 2; 4 house= 6 total) with NorthstarNSB-AGM31M AGMs (rated @ 103 Ah -totaling 618Ah).With this in mind, I am also updating my current 50A charger and would like to use 1 or 2 Xantrex Truecharge2 charger(s). I would like to have the highest charge rate possible without causing any battery damage.  - Steve

Answer:

Hi Steve, when sizing a battery charger, you want to size charger amperage to be about 10 – 20% of deep cycle battery capacity. In your case, 10-20% of 515 amp-hours, in other words: 50 to 100 amp-hour of capacity. You could have two Xantrex 50 in parallel for this size of deep cycle battery bank.  - Jeff