Installing an Onboard Battery Charger

DarkJester

Active Member
Jul 26, 2011
192
North Alabama, Guntersville lake, Tennessee River
Boat Info
2011 270 SLX
Engines
Merc 8.2 MAG Bravo III
Good day my boating brothers and sisters,

I dry slip a 270 SLX and it has no onboard battery charger and I would like to install one. I have 2 batteries 27M style. I am looking at a ProMarine on Amazon that will charge 2 batteries.
And of course I have a couple of questions.
Anybody done this? What pitfalls am I looking for?
I have a battery switch ( OFF, 1, 2, Both) I assume because of the way the instructions read the switch position makes no difference.
Does it come with the AC input side of the connector? I don't wanna drill a big hole for a receptacle, I figured I could put a standard Marine connector on there and secure it with Velcro when not in use.
This Appears to be a "Smart" Charger. If I were to leave it for a couple of weeks in the off season, would I come back to a huge hole blown out of the side of my boat?
My Marina/Dry Slip Guys are not the most diligent, and the Marina is about an hour away from the house, and they are only open until like 6pm etc. So checking on it might be an issue.
My reasons for doing this?
They are big batteries and in a tucked away part of the engine bay. Difficult at best to pick up a 50 pound battery and swing it up into the cockpit. Then put it up on the sunpad, then move it to the swim deck, then climb down and lift it up over my head then off to the truck every weekend. It would be easier, and safer just to charge them onboard.
I'm looking for opinions and advice.
Fire away!

Jester
 
Pro Mariner makes a good product, you'll be fine with one of them. Typically, you wire directly to the battery, although sometimes the individual battery switch legs are used. Some chargers come with a "plug" end (like a regular 120V appliance) while others are designed to be hardwired and used with shore power. You'll also need to look at where the charger will be mounted... both from a moisture standpoint and an "ignition protection" standpoint. You'll have to figure that part out for yourself and what makes the most sense for you. HOWEVER, you CAN NOT have a "plug" in the bilge with a gas engine. All connectors there must be permanent.

GOOD quality smart chargers can be left on 24/7/365.
 
OK, you gotta explain why the switch has to be OFF. Since the Charger is directly wired to the batteries and the boat is not running (no Alternator output) then why would it matter what position the switch is in?
Happy to.

With the switch on, whether its on #1 or #2, you might be supplying parasitic draws that could keep the charger in a charge mode, never entering its maintenance/idle mode. These on-board charges are not power supplies intended to deliver to a constant load.

With the switch on the 1+2/BOTH position, you basically make all the batteries into one large bank. This prevents the smart charger from evaluating the charge needs of each bank individually. This is very important for a true house bank, as its likely the bank that needs the most attention.
 
Happy to.

With the switch on, whether its on #1 or #2, you might be supplying parasitic draws that could keep the charger in a charge mode, never entering its maintenance/idle mode. These on-board charges are not power supplies intended to deliver to a constant load.

With the switch on the 1+2/BOTH position, you basically make all the batteries into one large bank. This prevents the smart charger from evaluating the charge needs of each bank individually. This is very important for a true house bank, as its likely the bank that needs the most attention.

The Promariner 12x0P series are smart enough to handle a constant parasitic load, and still not over charge your batteries. In addition, they are ignition protected and can be mounted in the bilge assuming adequate ventilation. They are truly set and forget. No need for special switching protocols or for holding your mouth at a certain angle.
 
Yep. I installed one of these ProMariner 2 bank chargers a couple years ago. The cord is about 6-8' long. I mounted mine in the engine compartment and routed the cord up along the transom to a plug in the cockpit. My concern when I bought it was the cord length. My boat stays in the slip on shore power with the battery switch off and the charger plugged in 24x7 unless we are away from the slip. When we are at the slip on shore power but hanging out the battery switch is on (doesn't matter which position).

My original plan was to mount it in front of the engine but the cord wasn't long enough so I called ProMariner and after talking to them mounted it closer the the transom behind my raw water pump.
 
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