Adding a Third Battery

rinkedout

I will be adding a third battery to my 290ec along with a battery connected inverter to provide power while at anchor. The 3rd battery will run parallel with the "house" battery. Anyone advise on the proper way to connect the batter charger in this scenario? Do I need to account for anything with alternator charging while boat is running?

Thanks, Rinked Out (Buffalo, NY)

DanD2

No issues with charging at all. Make sure you connect in this sequence....Bat#1, pos from charger, Bat #2 ground. Do a search on here, there is a diagram somewhere's.

DanD2

Stole this picture from one of frenchships posts....I believe Michael T also had the same picture.... This is the correct way to wire additional batteries.

rinkedout

Thank You DanD2;  Greatly appreciated!

Cableguy Greg

I added a second house battery to my 280EC. I put in 2 group 31 batteries. The only issue I had was the batteries are on the same side of the boat as the fresh water tank. With the tank full, the boat listed to the port side. I ended up moving the second house battery to the starboard side of the boat, which has leveled the boat out. 

Willhound

I did the same as @Cableguy Greg and placed 2nd house battery as far starboard as possible. If you do so, make sure to use decent marine rated cable of the proper gauge to avoid any issues. 

Cableguy Greg

I used #2 gauge wire that is rated for marine use. 

Ian

With the slight starboard list I have without a gen, an extra battery on the port side sounds like a good corrective measure. 

Spyderweb

I just compared a photo of my 2 house batteries (now buried under shrink wrap 100 miles from here) to the above picture of a correct wiring.  My "To Loads and Charge Sources" both come in from the left side.  What's the downside of having it wired this way, as it appears to have worked.

LaRea

It has to do with how your charger operates.  Wired incorrectly, the last battery in the bank would receive less charge current than the others.  Here's a decent explanation:

https://www.iotaengineering.com/pplib/balancedcharging.pdf

You're right that it will work either way.  But you might see a slight gain in performance by wiring them correctly.  

Cableguy Greg

I had mine wired like the picture above. Unfortunately I had to move the second house battery to the other side of the boat and I had to go back to a typical parallel setup.

Dream_Inn

Nice little article @LaRea !  I can't say I've seen the connection for 4 batteries (I just have two house), but it does make perfect sense.

LaRea

My guess is that it doesn't make a huge difference when you only have two batteries, and it's more important for big boats with 4, 6, 8 batteries.  

The first time I heard of this was 2015 when @Michael T brought it up.  Lots of web sites mention it, but I didn't really understand it until I found that article from Iota Engineering.  

Spyderweb

Good article.  Makes sense you're losing amps with longer wire runs from the charger, therefore unbalanced charging.  I kind of agree it likely wouldn't make a huge difference with just 2 batteries, but it can't hurt.

In my system below, the house bank is the 2 batteries on the right.  The charger is out of the picture on the far right.  It appears to me that the 2 charger leads both attach directly to the center battery. To even the amps up a bit, I think I can just move the red cable from the center battery over to the red lug on the right battery, as indicated by the arrow.  

Am I interpreting that correctly?

Paul 

LaRea

That would do it, or you could move the ground wire.  Whichever is easier.  Then label them for future reference.  

pistole

pistole

pistole

pistole

pistole

https://www.impactbattery.com/blog/tutorials/how-to-charge-marine-and-rv-batteries-in-parallel/

Stodge

Considering most battery chargers have more than one charging bank that example may not be real world.  I have 3 banks of batteries: port starter, starboard starter and house which is 2 batteries in parallel.  Each is on it's own bank circuit off the charger.  The house could see a little imbalance.

MarkB

pistole said:

Ingenious!