New Batteries, Second Alternator or New Chargers ?

[noelex 77]

Originally Posted by Jon Hacking

We went with Sonenscheim batteries that can be cycled to 50% 2,500 times.

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The Sonenscheim batteries are excellent in our first boat we get 16 years life out of them and our current boat 10 years and 12 years.

Originally Posted by Jon Hacking

. Therefore, a bigger bank will last longer. We seldom discharge more than 10% of our 660Ah bank overnight, & our solar panels usually fill that back every day..

This is very true and is often quoted, but I do not think it tells the whole picture. If you look at the economics I would expect for example 12 years life discharging the Sonnenshein batteries most of the time to 10 % with occasional deeper discharges. If you halved your battery bank to 330AHr and discharged to 20% with occasional deeper discharges, the life might drop to say 10 years. (If using conventional wet cells if you halved the life in both cases to 6 and 5 years the projections are realistic.)
The point is it would be much cheaper for your battery bank to be smaller. You would also reduce weight (especially for a cat) and have more storage space.
Things can change a lot in 10years ,Lithium batteries may be a good option , or you may have sold the boat.
A smaller bank is certainly not always the answer and may not be in this case, because of factors not mentioned in a short post, but I think many cruising boats with large wind and solar capacity are tending to go for a battery bank that is larger than is necessary.

[night0wl]

Seems to me that if your fridge is cutting out due to low voltage every night, then you're discharging your batteries way too low. Even if they're deep cycle, I would make it a habit to vary your discharges to only 80-50% (mix it up, batteries hate patterns) before topping up to full.

Also, try equalizing your batteries to see if you can knock off some of the sulfation on the plates...but I suspect they're too far gone at this point.

[Seahunter]

Originally Posted by Hugh Walker

The boat is a 2009 Beneteau Oceanis 46 with a 560amp battery bank (we think damaged so holding less). We have a standard 80amp alternator on the Yanmar 75 and a 5.5 KVA genset with two 40amp chargers. Our daily usage would be around 110amps per day.

This is pretty much the standard setup on a 42S. While your batter bank is sufficient with the amount you're motoring you could certainly add another 8D to pump it up a notch. My guess you're running a Whisper 5.5 genset? These can be setup to auto start when the batteries get below a specified voltage/amperage. In most of the systems we work on it's rarely the batteries that are an issue.
As for adding an alternator. There is a bracket available for the Yanmar secondary alternators but requires specialized (and unauthorized by Yanmar) mounting and serpentine kit. You could also replace the current alternator with a 9 series Balmar (150 amp) without stressing the mounting system (recommended) or step up to a Balmar 95 series, but you'll need to be a little more creating with mounting, belts and regulator.

Our current problem is the batteries seam to be giving us less and less output. We have a Xantrex Link Pro and I changed the settings to reflect 400amp capacity (about 2 months ago) but recently our fridge has been turning off overnight due to low voltage when the link pro is still reading 63%, something is amiss.

Do a complete reset of your LinkPro. Make sure the settings are current to your batteries' manufactured specs. (voltage high and ahrs are important) Reset your charger(s) to battery specs as well. Now you can check your regulator. (check engine and genset separately) You can either use a volt meter or better a clamp-on ammeter.

I was talking with another owner last night and with a slightly larger yacht and he said his life changed when he installed a second alternator.

Read above. Do your own research on adding a 200+ amp alternator to a Yanmar 75.

So I think we have 3 possible solutions;
1. Replace the battery bank.

Last thing to do. Make sure (distilled) water levels are good.

2. Install a second high capacity alternator to the main engine.

Not recommended.

3. Install new higher capacity charger for the Genset.

Unnecessary.

Which is the best option for a limited budget?

Reset all, test, add water and reprogram the genset to autostart. The cost; a couple a bottles of distilled water.

[btrayfors]

Lots of well-intentioned advice in the above posts. Some of it is IMHO right on the mark. Some misses the mark -- by a wide margin. Some is just plain wrong.

Let's start with basics.

1. A 560AH battery bank is ample to handle your daily usage (~110AH). No problem there.

2. Your present bank has lost a great deal of capacity. You didn't say how you measured capacity, but if your figures are anywhere near correct it is time to replace the battery bank.

3. Flooded lead-acid batteries are the best bang for the buck for most boats. BTW, flooded, AGM, and gelled batteries are ALL lead-acid types.

4. How you treat your new batteries will determine how long they will last, i.e., how long they will retain sufficient capacity for your needs.

5. All batteries begin losing capacity when they leave the factory. New batteries can vary enormously in measured capacity, and none of them reach their design capacity until after several cycles (discharge, recharge and, for most, equalization).

6. Batteries lose capacity thru a number of mechanisms including sulfation, stratification, corrosion, plate damage, contamination, and others. The most important of these is usually sulfation, i.e., the formation of lead sulfite crystals (PbSO4) on the plates. Left there for long, they will embed themselves permanently in the plates, limiting the area available for electro-chemical processes and, therefore, capacity of the battery.

7. The best way to protect against sulfation is to fully charge the batteries as often as possible. With many batteries, it's also necessary to equalize them periodically, applying a voltage of 15.5VDC or greater for several hours. You shouldn't do this too often, as each time causes a bit of deterioration of the battery, but it is a necessary step for many batteries.

8. Simply maintaining batteries at a float level of 13.2-13.8VDC will not, in and of itself, prevent sulfation and loss of capacity over time. You really do need to step up the voltage occasionally.

9. "Two 40A chargers" really is unlikely to cut it, unless they are specifically intended and designed to work together (like two identical Iota DLS-45/IQ4 chargers). If they're not, then one will be fighting with another and you're very unlikely to benefit from their total capacity. Much better to have a single 80A or better charger. With your onboard generator, a charger like the Iota DLS90/IQ4 might be a good solution -- it puts out a genuine 90A or more for as long as is required. And, it's particularly tolerant of generator-provided AC.

10. A larger alternator or a second alternator -- both with external smart regulators -- might be useful, but would be costly in either case. If you're motoring a lot, the existing alternator with a smart regulator should be easily capable of handling your 110AH daily battery draw.

FWIW,

Bill

[CAELESTIS]

I can't comment on the battery types or size, as experts that know far more than myself have already done so.

If you decide you need a bigger alternator, I strongly recommend the Altmount.com hardware for the Yanmar and a large Leece-Neville alternator. Leece makes the alternators for Balmar, which can be obtained for a fraction of what Balmar charges (without the white/blue paint job).

[hellosailor]

Hugh, as Jon said, your battery life will be very much affected by the depth of discharge. If you compare the claims of different battery makers and add a huge grain of salt whenever they say "UP TO...CYCLES", you'll probably see that you get the best overall power from batteries when they are discharged and recycled no further than the 30-50% discharge point. 30% would give you great battery life, but only 200AH of useful power from a 600AH battery bank. 50% would give you 300AH, but many battery makers would say it also cuts the number of charge cycles significantly as compared to 30%. Somewhere in between is reality, versus how much battery space and cost you can afford, and how often you can charge them.

So you really need to look at the whole picture, because the more money you put into the system up front (in battery capacity and a proper charging system) the less money you will actually spend over the life of the batteries. It is very much like the old ad line for a muffler shop chain "You can pay me now or you can pay me later" but either way, you will pay. I'd say put it in up front, and enjoy not having to change the batteries as often. Especially since the price of lead keeps skyrocketing, and the next set of batteries may cost twice what this year's set does.