Adding house batteries

[Benalisa]

Has anyone added additional house batteries to an EC280? I am thinking of adding two Blue top Optima (D31M) to the house circuit (three batteries total for the house circuit). Should I replace the exsisting battery to match the new pair? Will the factory charger still work for this set up? I have read about some differences between charging SLA and Gel but am not an "electrical" guy.

[Talon]

I would ensure that you keep all the batteries in each bank the same. You also want to make sure your charger can handle the extra load. I'm not sure what model charger your boat comes with - do you happen to know?

[Benalisa]

I don't know the model number but it is an Intelli-power. I would assume it would be the smallest one PD2120. The manual does state that you should use all the same type batteries (I guess it helps to read the manual). It doesn't tell me the max. number of batteries that can be connected to the charger. There seems to be three circuits but can I run three batteries in parallel on one circuit?

[Dream 'Inn]

First off, as said, have all the same batteries when connecting in parallel.  Also, replace them all at the same time, otherwise an older one will ruin the newer.

Now, as far as how many, my first question is what are you intending to do to make use of these batteries?  Typically, the only reason I see someone using more than 2 house batteries, on boats our size, is for stereos.  Although those without generators  that want to stay on the hook for more than a couple days at a time is a good reason too.

Connecting 3 batteries in parallel should not be a problem, just remember it will take 3 times as long to charge them back up.  The reason is because the 3 batteries, when in parallel, will act as one large battery.

FWIW, I did a ton of research two years ago when I was replacing my house batteries.  Really wanted to go with the best gel type, possibly optima, battery.  After lots of thinking, I decided that really the amp-hours is what I was concerned about.  Went with 2 new batteries from Wal-Mart at $60 each.  I have been extremely happy with the performance, easily being able to go more than 24 hours without even thinking about running the genny. (means a lot coming from someone who always thought I should have the best battery in everything).  Now, with that being said, your number one culprit of draining your battery is your fridge.  I have found out I don't need it turned more than half way up without it still keeping things cool.

Either way you go, make sure to keep the batteries above ~11.8V.  Here is a decent source to help you figure out what you need http://www.windsun.com/Batteries/Battery_FAQ.htm .  Good luck.

[Talon]

excellent point about the fridges. I generally turn the cockpit (drinks) fridge way down overnight and then turn it back up in the morning. It makes a huge difference in power reserves.

[Benalisa]

Thanks for the responses. The batteries in the boat are only one season old, so it seems like a waste to replace them. I will look into buying two more of the same battery. The charge time is not really an issue as the need for the extra batteries is to stay on the hook longer while running the fridges. So at the end of the weekend I will hook back up to shore power and they can charge all week ready for the next outing. I will also use the extra weight as movable ballast.

Will these "smart" chargers still be able to "condition" 3 batteries in parallel?

[Dream 'Inn]

Your answer for charging all 3, yes, it should not be a problem.  It will see it as just one, but just take a bit longer to charge (& yes, it will take a while).  Not a big deal, I used to be in the same situation with my 24'.  I just went with 2 deep cycle batteries instead of a starter one.  I think you will be surprised how much more just one more deep cycle in parallel will do.  Also, as I've said already (sorry, I feel that urge to repeat ), turning the fridges down will help an unbelievable amount.  Believe me, when I turned mine half way down and left it, I can go almost 3 days on the hook without even running the genny if I want (I've done it).  I just don't do it because I run the genny for other things anyhow.

Definitely go for it, you will be extremely happy you have!  You will also be glad you didn't go overboard on the cost of them.   (more money left for gas)

[merwin10]

From your description model number you have a 20 amp charger! Assuming that you have three house batteries and one starter battery you will split the 20 amps amoung the bank of batteries. Just remember that if you have 3 - 75 amp hour batteries in paraellel you have 225 amp hours available! Remember never to discharge below 50% point so 112.5 amp hours is your limit! Now taking that even at 20 amps of charge from the charger it will take about 5.6 hours to chage the batteries back to full charge!

As you state this is not a issue as you have all week to cahrge the batteries up! However, be assured that if you are on a extended trip with over night anchorages your engine run time won't be enough to fully charge the house bank! Oh you say but the engine has a 70 amp alternator! Well yep it does and it has to run the engine at about 10amps, your electonics at about 15 amps, keep the food cold 12 amps, run the "sound system" 15 amps and charge the battery banks! So you have 23 amps left to charge the battery banks! So when was the last time you ran the boat somewhere for 5 hours?

Mike -