Best Way to Charge 3 AGM Batteries on Boat

Updated 01/04/2023 | Published 01/03/2023

Question:

I am looking at this charger for my boat. I have 3 AGM batteries total. One is completely isolated as starter. The other two are connected in parallel. My questions is: Can I use this 3 bank charger and connect directly to each battery? or should I buy a 2 bank charger and use one lead for the starter and one lead for both batteries in parallel positive to one and negative to the other? There seems to be some conflicting info on this site - i saw a note on the 2 bank charger version of this item where someone was asking about connecting a 2 bank Noco to diesel truck dual batteries also in parallel and the etrailer advice was to use the 2 bank charger and connect to each battery. In fact, the advice suggested that the preferred method was to use a two bank charger on this. What is the best way to do this? Thanks

asked by: Derek

Expert Reply:

The method you mentioned, using the 3-Bank NOCO GENPRO On-Board Battery Charger # NOC74FR for your 3 batteries, is the best way. And it sounds like that's what the other answer page stated, if I read what you said correctly.

Technically you can charge a bank of batteries with a single charger but it's best to have each battery charging on it's own with wall chargers so that you know you get the best reading and charge for each battery. Sometimes if you charge a handful of batteries with a 1-Bank charger it can get a false reading and all of the batteries in the setup won't get a full charge.

The best way to charge any type of battery bank setup is to charge each battery individually so you'll want to separate your batteries that are connected in parallel while they're being charged.

expert reply by: Jon G