On board boat battery charger

[Newf]

Just installed this one a few months ago. I do not disconnect anything from the battery on mine.

 

[Copper Moon]

Just installed this one a few months ago. I do not disconnect anything from the battery on mine.

View attachment 71382

I have the same thing but a 4 A single battery connection with a Blue Sea add a battery system for the 2nd battery. I use it to top up my batteries overnight when pulling prawns.

 

[Fritz]

Looking at adding one of these to the boat when it’s sitting. Do u guys leave the everything connected to the terminals? Battery is isolated with a switch.

Okay,
I have a Noco charger on my boat and it’s a great entry level onboard charger.
It will automatically perform a charging cycle for deep cycle or starting batteries as long as you set the battery chemistry ie. AGM, flooded ect.
If you have a battery combiner, ACR, VCR that parallels your batteries it will do it with the master switch turned off!
If your ACR is installed as per BlueSea Systems recommended diagrams with the optional ACR shut off switch via the relay terminal ground you can run a charger like Noco with terminals for two separate batteries. If not you can charge both batteries from a single charger on one set of battery terminals because the ACR will automatically parallel the batteries.
The plot thickens! If you use one charger to do both batteries be wary of the amp HR capacity of the charger. Most chargers are good for a 120 amp HR capacity battery. If you have an 80 amp hour battery and a 100 amp hr battery connected via the ACR it (technically) becomes a 180 amp hour battery because you’ve greatly increased the charging surface area of you’re batteries when they’re connected in parallel.
My digital charger was throwing a fault because when my starting battery hit 13.8 ‘ish volts the batteries would combine and the voltage change would shut the smart charger off.
I have installed an ACR shut off and now my batteries also charge on different schedules (which is good). The deep cycle will charge for 6-18 hrs or so at 1.5 amps (like it’s supposed to) and the starting battery charges hard and fast (like it’s supposed to).
Bottom line is onboard chargers are cheap compared to replacing marine AGM batteries. How you do it is your decision.

Happy Thanksgiving everyone!