Upgrading house bank and charger

Don S/V ILLusion · Apr 17, 2010

Seems like this is one of the most over-analyzed parts of boating and everyone has their favorite setup.

Your two options for batteries is virtually identical in terms of total amp-hr capacity. It's a difference without a distinction which type you choose and the fact that you have a portable generator makes it almost irrelevant as you can recharge at will.
About the only thing I would suggest you consider is changing the current switch in favor of a simple cross-over switch which obviate the possibility of killing all the batteries simultaneously.

Maine Sail · Apr 17, 2010

nautikaljeeper said:
Question I have:
1. I 2 4Ds better than 4 group 31 for house bank?

No not really, 4D's are bulky, hard to move, and pack a rather low amount of Ah's into a large heavy foot print.

Most 4D's range from about 160 Ah's to about 190 Ah's each yielding a bank ranging from 320 Ah's to 380 Ah's. Some group 31's such as the Trojan SCS-225 pack 130 Ah's into a small footprint. A bank of four SCS-225's would be 520 Ah's in roughly the same footprint but easier to move and install without also requiring spinal surgery. Also, a bank of four 6V golf cart batteries would be in the order of 450 Ah's and still easier to move and very long lasting.

nautikaljeeper said:
2. Is protech 1240i a charger I would want to use? http://www.pmariner.com/productFeature.php?ProductNum=63341

Going from a 30 amp charger to a 40 amp charger is not going to do much in the way of improvement for the expense outlay. You may want to consider the Iota chargers with the IQ4 smart controller option. They will cost you far less and pack a lot more amps for the price. A 2000i Honda generator will run about a 55-60 amp charger though I have heard report of an owner running a 75 amp Iota on a Honda 2000i.

nautikaljeeper said:
3. If using this setup will I have to upgrade my 60 amp alt?

Scott

A 500 Ah bank is a little large for a 60 amp alt. This does not mean it won't charge but your batts will take more current than your alt can give them and your charge times will just be slightly longer. Personally I would run it for a season and see how you do.

Wet cell batteries can generally accept about 20-25% of their 20 hour Ah rating. So a 500 Ah bank can theoretically take a 125 amp charge in the bulk charge phase. That being said, a 125 amp alt would require a dual belt set up so an alt in the 90 to 100 amp range may be better suited than a 125+ amp alt. If you go AGM I would advise external regulation and temp sensing for at least the alternator but also preferably the batteries too.

For now I'd keep what you have except for the batts and run it for a season and see how you do. A battery monitor would be tops on my list before upgrading anything beyond the batts...

sailingdog · Apr 17, 2010

Four Group 31s are probably a better choice than TWO 4Ds. First, they're easier to install and easier to position, and give you more options in where you can put them. Finally, they will give you a bit more redundancy, since if any one of them fails, you'll lose less of your house bank. Another good option would be 6 VDC golf cart batteries, four of them would give you about 400-450 amp-hour battery bank @ the 20 hour rate.

If you're going with AGM batteries, be careful, as they may draw too much for your current alternator.

As for the charger, I think you'd be better off with an Iota battery charger. They're a very good charger and a lot less money per amp.

You're looking at a 400 amp-hour bank. I'd point out that a battery bank that size would really be better off with an 80-100 amp charger, if you're going wet-cell, and even a bit larger if you're going AGM. In general, a wet-cell battery bank should have a battery charger equal to about 20-25% of the amp-hour capacity in size.

nautikaljeeper said:
I have a 06 Hunter 36 and would like to have some feedback on upgrading my current system which is only 2 group 27 AGMs which supply house and starter banks. The boat is equipped with refrigeration and a freezer, autopilot, electric cabin top winch, and the common 12v accessories. The boat's current charger is Protech 1230 and a stock 60 amp alt with a 1-2-B switch. The direction I am thinking about is 2 4Ds for the house bank and 1 group 31 for the starter. I would like to stay with the 60 amp alt for now but am looking at the protech 1240i for the charger. The boat is mostly used for day sailing and will include 2-5 day anchorages. I am planning to carry a portable generator capable to run the 1240i when at anchor. If needed at a later date I will upgrade the 60 amp alt. or if I could use a switch to (amp manage) as in reference to Stu Jackson's link http://c34.org/bbs/index.php/topic,4669.0.html. As I said this is just the direction I THINK I should go. As I read more information it just seems I get more confused as to which way to go. I would like to keep it as simple as I can but want to INVEST in the right way.

Question I have:
1. I 2 4Ds better than 4 group 31 for house bank?
2. Is protech 1240i a charger I would want to use? http://www.pmariner.com/productFeature.php?ProductNum=63341
3. If using this setup will I have to upgrade my 60 amp alt?

Scott

Damn... Maine Sail beat me to it...

woodster · Apr 17, 2010

not trying to steel this thread ...but i would like to know if the AGM battries are the same kind that are in the computer back up systems

regards

woody

txtowman · Apr 17, 2010

answer

yes
my agm bats are cast offs from nasa
just be sure to use a charger with an AGM setting for charging them

Snotter · Apr 17, 2010

It is true that the group 31s pack more wal-up in a smaller space than the 4Ds and they are easier to handle; however, 4Ds carry more water which mean they can go longer between waterings. Also, their greater size allows them to disapate heat better.

When my battery charger melted down last fall, my 3 group 27s bit the dust but my 3 4Ds are still very much alive and well dispite the fact that the group 27s were newer. I was very much relieved, though, that I didn't have to lug 3 4Ds out of the boat, to the store, from the store, and then back into the boat. I would pay someone to move the 4Ds.

Bill Roosa · Apr 18, 2010

Couple of physical facts to consider

Just because a battery bank can accept 20-25% of its AH capacity does not mean it is smart to buy a charger or alternator of that capacity. It depends on how you use the batteries. If you cycle the batteries in the 40-50 % charged range then you could probabaly take the full output of the alternator/charger. If you are cycling in the 90-95 range then you will not be even able to get 10% of the AH capacity as a charging rate.
So before you spend some money you will want to understand how you are using the battery bank.
Cycle at lower % charged ranges and the batts can accept the bulk (20-25% of AH) rate but the total number of charge cycles before batt failure falls WAY off. Your charge times do go down however. Cycle at higher % charged ranges and the batteries will not accept the full charge rate (acceptance or float) but they will cycle many more times before failure and you will spend more time charging them.
For day sailing with a week between discharges a very small charger is all you need (10 amp) because you really don't care about rapidly charging the batteries. For extended cruising you (typically) want to minimize the amount of time you run the engine so they tend to cycle in the 75-80% charged range. Basicly trading cost of bank replacement for charge time convienyance.
Now if you have wind or solar the whole charge time thing gets screwy as it is another variable.......
To the end of uncovering where I was cycling my battery banks I built a spreadsheet that does just that. Email me for a copy (william-roosa@us.army.mil)

Al - s/v Persephone · Apr 18, 2010

My 05H36 set-up

Scott -

Since no one else with an H36 has yet responded, I thought I'd share my particular mods.

I have a Link 20 dual battery monitor, which told me what my loads were for various equipment, and my battery usage over time. If you don't have a ground-shunt-based battery monitor, you really have no way of measuring what you'd otherwise be only theorizing about. I strongly urge this as your first purchase in upgrading your installation.

Persephone came with a pair of group 27 batteries labeled "CBC' with a model number of 27DC24. When considering additional capacity schemes, I first wanted to understand what I had.

I found out that "CBC' meant Crown Battery Corp. and that they are considered by many the premium supplier of lead-acid, heavy-duty, deep-cycle, industrial batteries, due to their batteries' having the thickest lead plates.

The 27DC24s do feel like they weigh a ton - a lot more than any automotive battery I've lifted. (Though, in fairness, those were starting batteries designed for plate surface area per amount of lead). For their 51lb weight you get a conservative 105Ah. (Crown's 27DC36s fit the same height and footprint, but give you 115Ah for an additional 8lbs of lead.)

I have most any kind of electronics you can think of (see http://hunter.sailboatowners.com/index.php?option=com_kb&Itemid=267&cat_id=71&aid=7636&page=article&mn=36 )

Consequently, I added a third 27DC24, giving me 315Ah - quite sufficient for my needs, wiring it to allow me to arbitrarily select any one, any pair or all three batteries in parallel.

I mounted it in a box in the aft-most setee locker, where my charger (upgraded from the stock ProTech 1230 to a 1230i - designed for 3 batteries) is located.

I used custom red 00 gauge cables (from http://shop.genuinedealz.com/Items/...&caTitle=Custom Cable Assembly - Labor Charge ), even though the short run through a 300amp fuse didn't really require it.

I wired its positive terminal through another Xantrex TFB300 fuse (like the two for the existing batteries in the sail locker) to the "battery" terminal of a Blue Sea 6006 SPST switch mounted just under the existing "1-2-both" selector switch beneath the nav desk. (I marked the 6006 with a "3" by its "on" position.)

The wiring for my SSB radio crowded the existing switch's terminals, so I moved it to the load terminal of the new switch, which I was then able to wire back up to the center pole (load) of the 1-2-both switch.

The ground buss bar mounted near the port inner stay's lightning bypass cable made for an even shorter run, but as with the unnecessarily thick 00 to the switch, I used a custom 00 cable (yellow, of course) for the negative circuit.

If I feel the need, I can parallel any one, two or three of the 27DC24s - whose characteristics match well with one another. For everyday use, I can use any of the batteries alone to start the engine - a "listen to how it grunts under the load" daily test.

No permanent paralleling of good with possibly bad batteries.

Fair winds,
Al - s/v Persephone

Maine Sail · Apr 18, 2010

nautikaljeeper said:
Most replies agree with having a way to monitor battery draw. That will be a definite addition. Thanks for your suggestion. Your last point about paralleling with a bad battery is my only reason not to go with group 31s. I really don't want to handle 4Ds and as Stu stated there are 31s with more Ahs run in parallel. Just to clarify I don't have AC just separate refrig and freezer. Again thanks for your help.

Scott

Scott,

All batteries are basically made up of individual 2 volt batteries inside a case. 6V batts have three 2 volt cells and 12V batts have six 2 volt cells. Any one of these cells can go bad whether you have 4D's or 4 group 31's. It however is a very rare occurrence with good quality deep cycle batteries..

If you have a bad cell in a 4D the whole batt has to be taken off line but with four batteries only one of them needs to be taken out of the loop leaving more reserve capacity in the remaining banks.

Lee Coller · Apr 18, 2010

nautikaljeeper said:
Most replies agree with having a way to monitor battery draw. That will be a definite addition. Thanks for your suggestion. Your last point about paralleling with a bad battery is my only reason not to go with group 31s. I really don't want to handle 4Ds and as Stu stated there are 31s with more Ahs run in parallel. Just to clarify I don't have AC just separate refrig and freezer. Again thanks for your help.

Scott

I learned more in my first trip after installing my battery monitor (Link 10) than I'd learned in the previous 4 years of owning the boat about my power usage patterns and what the batteries would accept.

Stu Jackson · Apr 20, 2010

It all depends on how it's wired

see: http://forums.catalina.sailboatowners.com/showthread.php?t=104505

similar discussion

Snotter · Apr 20, 2010

Stu Jackson said:
see: http://forums.catalina.sailboatowners.com/showthread.php?t=104505

similar discussion

Stu, I am really pleased with how my wiring turned out. The link you provided and past comments were timely. Though I have over 650 ah capacity, I am glad I went with a 75 amp alternator and the corresponding smart regulator. The kind of cruising I do doesn't warrant the hassle of putting in double belts to handle a larger alternator. Also, I feel my 60 amp house charger is a good size and fit. I sleep better knowing my alternator feeds the batteries through a circuit-breaker.

Rick Sylvester · Apr 20, 2010

Batteries do not "draw" current,

they accept it. In other words, a battery cannot "draw" more than an alternator can deliver as some posters have said. It may, however, accept as much as the alternator can deliver for a longer time. A relatively small alternator will work fine on a large bank but it will take longer to charge it. That being said, since the alternator will run at higher rates for a longer time (depending on your regulator settings) this could ultimately reduce it's life.

I would suggest that for the short term a small mismatch isn't a big issue.

I agree with the other posters on the 4D issues. Have you ever picked one up? In my last batch of aging group 27s I had one cell go bad. All I had to do was disconnect it and leave the remaining bank intact until I could deal with it.