Adding Batteries

[smokey73]

Background (1994 Hunter 40.5):

I am considering adding capacity to my house bank. Right now I have two 6V golf cart batteries located in my port aft lazarette. I do not have room for another set of batteries in my port locker and it would add to much weight to the stern anyway. I have added a 5KW generator to my Stbd lazarette. With that extra weight now in the stern, I have temporarily had to add about 200 lbs of ballast in the bow below the V-berth to keep her on her lines but I don't like carrying around dead weight.

Right now I have a 40 gal water tank just below the generator that I do not fill except if we are going on an extended cruise. I keep the 20 gal bow water tank full as ballast and just use the port and stbd (20 gal each) belly tanks for routine water needs. I think I've done all I can with easily adjustable weight that I can. If I ever race, I can empty all the water out if necessary to lighten the load but then I'll be squatting a little in the stern.

Now to the questions:
I don't like carrying around dead weight. Its about 40 feet from the bow to where the current battery bank is located in the stern. If I put batteries in the bow below the V-birth:
1. Do I have to use AGMs because of the ventilation (or lack thereof in that location)
2. I would assume I need a minimum of 2/0 AGM tinned wire from the fwd bank to the House Bank but is that even big enough?
3. Will this location and wire run generate a problem with charging/discharging the batteries equally (I would use new batteries for all 4)? I have a Sterling smart charger, and a solar panel with a smart regulator to keep the batteries topped off when on my mooring ball. Both brands/models recommend by Mainesail.
4. If I use AGMs for the house bank, and my start battery is a flooded cell lead acid battery that has a BlueSea ACR as its charge source, do I need to change the start battery to an AGM?
5. Any other advice.

Thanks in advance for the sage advice. I really rely on the collective wisdom of this board and especially the advice from Mainesail.

 

[Don S/V ILLusion]

Before you get too far down this path, it might be worthwhile reviewing how much your stern squats. We used to have a 40.5 similarly equipped but had no problem with a bank of 4 - 6 volt batteries in the stern locker. We also carried a 10 ft rib with an 8hp outboard on stern davits. All of which adds up to more than you described which makes me question the problem.

Under power or sail, the stern did squat which is normal for that hull. At rest, the bottom of the rub rail was only slightly above water. Is yours different?

 

[smokey73]

Before you get too far down this path, it might be worthwhile reviewing how much your stern squats. We used to have a 40.5 similarly equipped but had no problem with a bank of 4 - 6 volt batteries in the stern locker. We also carried a 10 ft rib with an 8hp outboard on stern davits. All of which adds up to more than you described which makes me question the problem.

Under power or sail, the stern did squat which is normal for that hull. At rest, the bottom of the rub rail was only slightly above water. Is yours different?

Thanks Don,

I'll measure the distance from the water to the rub rail at the stern. As I recall its about 7 inches. (that is with the 200 lbs of ballast installed and the water tankage set up as I have described.) I know it squats under power and am used to that. It just seems when I added the generator, it really set the stern down. I'm not set on the batteries but if I decide to add more capacity it seems that the bow would be the better place if I can solve the difficulties that may be involved in having the batteries 40 feet apart. I know some people put a battery in the bow for a bow thruster. When the ballast is not there the leading edge of the bow is barely in the water. Right now I'm just exploring options and am interested in getting feedback regarding widely displaced house battery banks. Before I put in the generator (about 250 lbs) it seemed to sit pretty well on its lines (assuming the boot stripe and bottom paint were in their original locations.)