Batteries.

[rockstar]

I hope to replace my house batteries on my 6 year old S/O 42i. What type should I be looking at?
Rockstar.

[Don Reaves]

You'll get a lot of different opinions, but I think most people will agree that more is better as long as you can charge them adequately.

I recently replaced the two 12-volt batteries on my SO35 with two 6-volt golf cart batteries. The 12-volt batteries had been wired in parallel, a technique that I think is ill advised, though Jeanneau seems to use it often. If one battery develops a shorted cell, it will almost always ruin the other battery when they're wired in parallel.

With 6-volt batteries, they would be wired in series, so this can't happen. And golf cart batteries are built very ruggedly and serve well as house batteries. Plus, the electric golf cart market is large enough that the batteries are quite common and relatively inexpensive. The only problem is that they are physically larger, so you have to be careful to measure your space before purchasing them.

Since I replaced my batteries, I've had much more power in the house bank, and I'm very happy with them.

Don

[davideso37]

Rockstar,
I have three house batteries and a starter battery in my 2006 SO37. The three house batteries are the original wet cells. Two years ago I added the fourth battery a sealed calcium grid dual purpose so that it is suited for both starting and draw down. The sealed calcium grid has worked well and the 80 amp hour battery fits in the space of the original 70 amp hour batteries.
I am in the process of replacing the three house batteries now just as a precaution and will use the sealed calcium grid battery and pick up the increase in the available power in going from 70 to 80 amp hours.
I thought long an hard about changing to sealed AGM batteries but could not get information about the suitability for starting duty. I was keen to keep all the batteries the same since they are all, including the starter battery, charged in parallel. The sealed calcium grid gave the safety I wanted, fitted into the existing very tight space on the SO37 and gave an increase in the available power. We have slammed around in the ocean for hours on end since installing the first calcium grid battery so after two years I am happy to use them for the full replacement program.
If you have more room and can find a charger that charges different styles of batteries at the optimum rate you may have more options but I wanted to keep it simple.
Regards

David

[reverie]

Don,

Were you able to fit the golf cart batteries (which are taller than the originals) into the battery compartment in your SO35? Or did you need to make some modifications to your boat to accomodate them?

John

[Don Reaves]

John,

The batteries almost fit. That is, the wing nuts were about 1/4 inch too high. I used a 1-inch hole saw to put holes in the lid right over the nuts. Other than that, they fit fine.

That said, measure first. There are different sizes, and some are taller than the ones I bought.

Don

[reverie]

Got it. Thanks, Don. I'll take my tape measure with me the next time I'm in the battery store.

[debenboy]

Don,
I too am trying to do something about the puny battery capacity on my 2010SO36i, which has 2x 70AH house plus 1x70AH battery.
I was considering 6V batteries to replace the house pair.

Some questions:
Which brand did you use?
AGM or flooded?
What are the physical dimensions?
Can you get a full charge out of your alternator?[bearing in mind the 25% rule of thumb for alternator rated output to total battery capacity]

My situation is compounded by the fact my boat is normally kept on a swinging mooring with only occasional recourse to shore power. I am considering a solar panel to "trickle" the batteries when the boat is not in use, and possibly a "smart " charger as first steps, plus possibly converting the fridge to a keel cooled unit, as that is the real killer.

[rxc]

I am a big proponent of 6v golf cart batteries. They are very close in size to the Group 31s that Jeanneau installs, and they have much better discharge characteristics as house batteries - designed for multiple deep discharge and hard service. I have a set of four that were installed in 2007, and they are still going great. I also like flooded cells because you can check their state and add water. It is not hard, and a good thing to do. Trojans are great. Trojan 105s are widely available, and if you look hard, you can also find 125s, which have better capacity at the same size. 145s have even more capacity, but are larger. Do a search on golf cart batteries, or see if you local Costco carries them, if you are a Costco member.

A separate starting battery, also flooded chemistry, is a good idea, and you also need to replace the Jeanneau battery isolator with a battery combiner. The solar panel with a smart controller is a good idea for a boat at a mooring.

The alternator that came on my 43DS was quite robust, compared to the ones that come with other boats, but I also think that a higher-cap alternator with a smart regulator is best. Only a smart charger will allow you to fully charge the batteries quickly. If you only have a 2-battery bank, you might be able to use your existing alternator and just add a smart regulator. If you are going to do some serious cruising, then a battery monitor is highly advised, as well.

[Deleted]

Debenboy,

6V golf cart batteries are a very good solution; but with the (limited space) boxes you might like to consider our SO36i fit:

In original box - 2X Trojan 30XHS, 130AH, wet, deep cycle batts
In well aft of the shower (2 cabin version) - original start batt
Dimensions: www.batterymegastore.co.uk/product/30XHS - they fit perfectly in the original box.

Very pleased with our Sunware 69W solar panel; we get several days cruising without alternator charging. It will certainly keep your batteries at 100% on the mooring; in the marina I have not used the mains battery charger for months.

Agreed re the fridge cooling; next on my list will be a seacock cooling system.

[Don Reaves]

Debenboy,

The batteries I bought were Energizer EGC2, which I purchased from Sam's Club for less than $70 US each. They're flooded cells, and easy to maintain. The dimensions (Length x Width x Height) are 10.25 in x 7.0 in x 9.25 in. The height, including the lugs and wing nuts is about 11.25 in. The batteries aren't marked with AH capacity, but instead indicate 105 minutes of reserve capacity.

I personally can't attest to the ability of my alternator to charge the batteries, since I do most of my charging using shore power. But they charge fine with the charger that came with my 2004 SO35. Our biggest power drain is the A/C, which doesn't have a 12V connection. My wife insists on being comfortable, else she would not spend much time with me during the summer. That's why we are connected to shore power most nights.

I looked at Trojan, which is a brand I respect. But since this was my first attempt at using 6V batteries, I decided to try something less expensive. (Much less expensive, actually.)

I agree with the other posts about solar panels. It makes sense to keep the batteries topped up while you're away. Lead acid batteries tend to discharge themselves even if you aren't drawing power from them.

Don

[dublin]

Why is nobody considering gel at terriers which give much greater usage power relative to nominal power AHr because they can e regularly discarged elbow 50% and will still recarge

[MartyB]

While gel batteries do allow a higher discharge amount, they are one heck of a lot more expensive than wet cell batteries. When you can put a few BIG 6V batteries together, the cost per AHr is much better. 6V do cost a bit more than an equal sized 12V per say, but they seem to last longer life span wise, and have more reserve. While I have not gone to 6V's for my boat, I did for a RV trailer I had, much better option than 12V batteries.

Marty

[debenboy]

Thanks Guys,

Lots of interesting info there.

Sunset,

Can you get a full charge on your 2x130AH trojans ( plus engine start) out of the alternator?
Have you got the solar panel mounted on the main hatch garage?

Thoughts are beginning to crystallise.

[Deleted]

Debenboy - I currently measure voltage only (must fit a battery monitor). The standard alternator appears to charge the 330AH of batteries OK, ie. it takes the charge voltage up to 14.3V.
Although I understand that we should expect the standard alternator/regulator to achieve 80% charge only, so far I have not felt need to upgrade the charging.

After engine shutdown the solar panel maintains voltage at 12.6V+ for ages. The Sunware panel is very expensive, but if you prefer anchorages to marinas then it's a great asset.

Yes, solar panel is fitted on hatch garage; with the cable taken down through the deck, then mast post to underfloor (will try and attach photo).

[MartyB]

Looking at another forum, one advantage to AGM's, is that they can lie on there side, giving you the ability to put them in places a water/lead setup can not. So the price may or may not be worth it in some senses, others. have to say yes!

Marty

[Don Reaves]

I use an AGM battery for the trolling motor in my little trimaran. I figure if I tip it over, having acid all over is not going make things any easier. Luckily, it's been very stable to date, even in 25 kt winds.

Don

[blackcaiman]

Wouldn't you know...

I've been away for a few weeks (on the boat). While out and about, we lost our engine battery, our guy asked me just this morning what kind of battery I would like to replace it with (hell if I know, I say). I come back home today and check out the site and there it is, a very current thread on batteries.... Gotta love this site. Gel it is...

[dublin]

Agm and gel seem to give close o double the available power for a nominal ah rating due to their ability to recover from a greater Evelyn of discarged. So the extra cost is outweighed by the fact that only af the rated rated ahrvis required.

[dublin]

d**n predictive text.

That was meant to be
Only half the red AHr is required so in effect half the numer of batteries so cost equalises

[Don Reaves]

The other nice thing about AGM batteries compared with Gel is that they charge using the same voltage as wet cells. So if you charger is set up for wet cells, switching to AGM means you don't have to adjust (or replace) your charger.

[davideso37]

Marty,
I understood that to be Category 1,2 or 3 compliant the batteries had to be AGM or Gel but the safety regulations just state "either sealed or gel filled type." I believe the new sealed wet cell are compliant at much less cost than the AGM or gel. Of course you cannot run the sealed wet cell on their side but I doubt this feature is used a lot.
Today on my SO37 I completed the change over to the four sealed wet cell dual cycle calcium grid batteries and I am very happy with the results.
Regards
David

[Mistroma]

I assume that my 2009 42DS will have a similar size battery box to the 42i. I'm looking at my existing batteries because I'll probably be living onboard for 6-7 months this year.

My options are:
1) Buy a cheap starter battery and move the 2009 orginal to the port side, giving a bank of 4x110Ah.

2) Replace 3x110Ah 2009 domestic batteries with 4xT105s

I'll probably go with option 1 if all existing 110A batteries have at least 80% capacity left when tested.

However, I'd still like to make it easy to switch to T105s in future if the 2009 ones fail. But I thought that would require changes to the port side box. It seems to have 2mm less width than required and is tight in height.

Making the box bigger would require removal of water tank to dismantle the box and re-build with a lower floor (assuming there is room).

I'd be really pleased to find that someone else did fit 4xT105s in the original box. Perhaps the sizes I've been given were wrong.

My other big worry is ventilation. I'm thinking of building fan assist via tubing from aft cabin through to the aft port locker.

Does anyone else have worries about existing battery ventilation system (i.e.None to speak of)?

[so40gtb]

I put Optima AGMs on my SO34.2 - two blue-top house batteries in parallel and one red-top starter battery. The total capacity of these is not quite up to that of the original flooded cells and the dimensional restrictions of the battery box preclude others having more effective use of the space they occupy. That said, they've worked flawlessly and I need not remove them during winter lay-up. I would definitely do AGMs again, but probably in a different shape format, if the box dimensions permitted it.

[reverie]

Hello all,

Coincidentally, Cruising World magazine has a great article by Ed Sherman in the February issue. It covers the various types of batteries, and the pros and cons of each.

He's not a fan of gel batteries on boats because of the stringent charging requirements of these. He says they shouldn't be exposed to more than 14.1 to 14.3 volts for any extended period - so you'd need to change the charging systems (alternator and charger) if you move to these.

He's a fan of either traditional (flooded wet cell) or T.P.P.L AGM batteries. The latter preferred if you truly need deep cycle maintenance and low (or no) maintenance. Obviously more expensive though.

Good luck.

John
Reverie - SO35

[rxc]

Mistroma,

I have a 43DS that originally had 4x110 wet cells, and I was able to fit 4 T-125s into the same slots with some "minor" fiberglass grinding. I don't know how your boat is configured, but on mine, the problem was that the depression in the boxes for the batteries was just a bit too small for 2 of the T-125s. Two fit fine, but the others were just a bit big. Also, I did have to shave a bit off the bottom of one of the wood covers to accommodate the terminals.

The grinding was not too bad. Just remove anything that could be damaged (or offended) by the dust, and use a good vac with a HEPA filter. I seem to remember that I took off the gel coat and a bit of the underlying fiberglass, because I only ground it on one edge (a long edge). If I had ground both long edges, it probably would have just involved removal of the gel coat.

Location of a separate starting battery, however, would be very boat-specific. On my old boat I had to build a shelf for it.