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  #1   IP: 76.28.45.109
Old 11-30-2014, 10:18 AM
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Third / starting battery?

I have managed to securely locate three identical group 27 batteries in our I-28. That gives us 345 AH@20A which has been all we need with a comfortable margin. At the same time I have made access to the aft end of the engine difficult. I am considering replacing one of the group 27 batteries with a group 26 that will fit under the floorboards in the bilge. That would give me the access room I need in the lazarette. The group 26 would have 525 CCA and would be dedicated as the starting battery.

What are the consequences of this change I need to anticipate?
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Old 11-30-2014, 11:29 AM
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Quote:
Originally Posted by gfatula View Post
...I am considering replacing one of the group 27 batteries with a group 26 that will fit under the floorboards in the bilge...
What are the consequences of this change I need to anticipate?
• Lots of nasty, sealed up moisture down there?
• Potential long cable runs?
• Fumes sometimes end up in the bilge. Fire hazard?


I have to ask? Do you really need 3 batteries?
If it were my vessel, I'd prefer the batteries were grouped together.
YMMV...
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Old 11-30-2014, 03:12 PM
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Quote:
Originally Posted by roadnsky View Post
• Lots of nasty, sealed up moisture down there?
• Potential long cable runs?
• Fumes sometimes end up in the bilge. Fire hazard?


I have to ask? Do you really need 3 batteries?
If it were my vessel, I'd prefer the batteries were grouped together.
YMMV...
That may just be my conclusion, too. Two is enough. Thanks,

G
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Old 11-30-2014, 04:36 PM
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I would do without the third battery or move it when it was in the way before I would go stuffing a battery in the bilge.
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Old 11-30-2014, 06:05 PM
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FWIW, I have 3 batteries. Two of Gp 31 for a house bank and a Gp 24 for starting the A4. Boat originally had two Gp 27 and an A/B/Both switch.
You're going to need a 'combiner' or voltage sensitive relay to connect the batteries for charging. My alternator (upgraded from 35A to 55A) currently feeds the house bank, then overflows to the start battery.
You haven't mentioned your alternator capacity or regulator, so I'm not going to try answering questions you haven't asked.
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Old 11-30-2014, 07:31 PM
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I am watching the reply's very carefully on this because battery replacement is one of my on going projects.
I have the same problem we all have (no space) but I want as much capacity as I can get and want to keep the weight down and centered in the boat. Reading Nigel Calder's book mechanical,and electric manual I just bought 3 Trojan 27 AGM/VLRA deep cycle's for my house bank and a Trojan TM deep cycle flooded cell for my second bank to run stuff like a SSB, new bilge switch with counter,high water alarm CNG sniffer,and a watch alarm and low battery alarm. These are low draw alarms but they are almost always on.I bought a OPTIMA RED TOP for starting.
Nigel says a larger bank is faster to charge and easy to monitor. Iam still cutting and drilling to fit this all in but think this is the way to go. I just wish the flooded was AGM but I screwed up.
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Old 11-30-2014, 08:02 PM
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Tom,

Did Calder recommend AGM's? If he did, was there any mention of optimal charging voltage? Any mention of different battery chemistries charged together? How about electronic ignition? Pending your responses I will likely have many more questions/considerations.
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Old 11-30-2014, 08:53 PM
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Neil I only read the same few pages about batteries about 20 times so it is still a little vague to me.Regarding the AGM he called them jell and he was impressed with the cycling ability but they would be better if they were all the same. Regarding the charging Trojan says the flooded and jell use the same voltage but Nigel said the jell will charge faster. I have been reading so much stuff about batteries the last few weeks that I am totally confused and my eyes hurt from watching the Oakland game, just kidding. I will get the book out tomorrow and check through it and get some real answers for you
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Old 11-30-2014, 09:04 PM
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Looking forward to it Tom. The big thing here is charging voltage and if you meet the AGM's voltage needs, the effect it has on everything else at the higher voltage (I've heard as high as 15 volts in the past), particularly the effect on the narrow volts-amps-resistance balance with our electronic ignition.

Regarding mixing battery types, imagine designing for a higher voltage to please the AGM's then charging a wet cell at the same voltage. My AGM experience was not positive. I now have 4 deep cycle GR29 wet cells and one GR24 no maintenance, isolated engine starter.

Also George, I vote for no battery in the bilge. No good can come from that.
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Old 12-01-2014, 03:37 PM
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Neil I feel like the guy asking the doctor for a free operation. Looked at Nigel's recommendations again last night, I cant tell if he recommends AGM or WET CELL, it is one of those (if you do this then you get this). Regarding the ideal charging voltage I would think the battery mfg would be rule but I haven't found out what that is yet.Nigel's recommendation of a larger bank being easier and faster to charge led me to go with a 3 battery house bank and 1 battery backup (battery 2 bank 2). For charging I am using the standard small alternator (35 amps ??). What I would like to know is what amps at what RPM, may take it to LUCO and have them check it out.Iam curious about your thoughts about battery composition because I need to buy 1 more to make my house bank. I have 2 new AGM and 2 new WET CELL, the odd battery goes to the power boat to run the bait pump etc.I have gone with a separate OPTIMA AGM start battery all the battery's are isolated from each other from the switch and controls who gets charged,no automatic switching etc. This electrical stuff just drives me nuts,its kinda like buying stock. You do your homework place your bet and hope for the best.
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Old 12-01-2014, 05:21 PM
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Hi Tom -

I think you need to be a bit careful. It's not stock picking but engineering, and you should be able to design a system that works for your needs.

Quote:
I have managed to securely locate three identical group 27 batteries in our I-28. That gives us 345 AH@20A which has been all we need with a comfortable margin.
A single, deep cycle, group 27 from Trojan has 110 AH @ the 20 hour rate at which point the battery is dead. DON'T do this.

With 3 group 27s, what you really have is about 100 AH to play with. Maybe a little less if your current draw is high (refrigeration, autopilot?) See below for where the 30% comes from.

I re-read some of Calder last night also as a refresher... His advice (as I read it) was that for the money, a well maintained, wet-cell lead acid battery is the best value. The caveat being 'well maintained', which he defined as regularly charged, watered and occasionally de-sulfated with a controlled over charge.

The AGMs don't self discharge as quickly, and are 'maintenance free' (which also means you can't maintain them.) AGMs were originally intended for automotive, with thinner plates and glass mat between the plates to deal with vibration, shock, and freezing conditions. They charge faster, but they are also twice as expensive.

Most, if not all of Calder's big cruising boat examples have conventional wet cell, lead acid technology.

He recommends a big single house bank, and a smaller, dedicated starting battery. The reason for a single big house bank is to have the capacity for intended use without deep discharge (defined as >50%) which will definitely shorten battery life.

His design goal was to assume the average cruiser will typically have undercharged batteries, and to only count on using the power between 50% and 80% of charge. That means you have a useful 30% of the total AH capacity of the bank before you need to recharge. The 50% assumes you never want to deep discharge, the 80% assumes you don't run the engine enough to make up the last 20% to full charge (this last 20% takes the most time). It's a very realistic and conservative approach.

If you haven't already, I'd suggest you follow the book and develop a listing of all electrical loads and duty cycles. This will really clarify your needs, and provide the sound basis for any further decisions. I did this several years ago, and it quickly clarified for me what I needed VS what I wanted, and how much money, time, and space made up the difference. I got what I need, which has actually been more than adequate for my use. YMWV, and you should do the exercise.
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Old 12-01-2014, 05:56 PM
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Quote:
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Tom,

Did Calder recommend AGM's? If he did, was there any mention of optimal charging voltage? Any mention of different battery chemistries charged together? How about electronic ignition? Pending your responses I will likely have many more questions/considerations.
As to E.I. all the blue water boats are diesel - not an Atomic 4 in whole book.

AGM and wet lead acid are the same chemistry so charging voltage is the same, but charge acceptance is very different.

Most of Calders examples presume the use of a multi-step smart regulator to deal with the requirement for a bulk charge, float, and occasional de-sulfation. The electrical portion of the book is primarily large power budget blue water cruising - although you can gather a lot of great ideas for coastal cruising / day sailing.
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Old 12-01-2014, 07:46 PM
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Jeff All good points for sure,thanks. My plan for the single WET CELL is to use it for the windless and the SSB the engine SHOULD be running when there used.The other time it will be used would be to power my alarms and bilge pump if I figure out how to set this up right.Per Neil I don't want to HARD WIRE them but I want to keep that battery off the grid unless its charging.Regarding setting up a power consumption plan that is a great idea except things keep changing,LED;S, new gotta have's.Every time someone post a site that has something cool I seem to buy it. I sort of got behind the 8 ball and had 2 boats that both needed batteries so 750.00$ latter I still need 1 more battery,so do I get another AGM @250.00 to make 3, or do I go to 3 wet cell's @159.00each-just bought 2 and cant return.The odd battery goes to a 15.5ft power/fish boat I re-did a few years ago and thought I should use it and or sell it. ITS all so dam confusing.
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Old 12-01-2014, 08:09 PM
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Been thinking about this...
Read somewhere some time ago that the AGM batteries become cost effective when you have high charge current capability (big alternator) and can use this capability to cut down your engine run (and maintenance) hours.
Other than that, they're not cost effective and flooded is the way to go.
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Old 12-01-2014, 10:33 PM
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gfatula,
I have three batteries. I have two Gr29's wired in parallel as my house, and a Gr24 as my start. House = #1 and start= #2 on my switch. I have yet to 'need' my start as a start. My two Gr29's house have 230 Ah.
Mine are all Wal-Mart lead-acid flooded batteries. I can't see the added complexity of other mixtures being an advantage at this point (AGM or gel).

YMMV as Jerry says.
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Old 12-01-2014, 11:18 PM
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Charging specifications from Optima

Quote:
Recommended charging information:

Alternator:13.65 to 15.0 volts, no amperage limit.

Battery Charger:13.8 to 15.0 volts, 10 amps maximum, approximately for 6-12 hours.

Cyclic Applications:14.7 volts, no current limit as long as battery temperature remains below 125°F (51.7°C). When current falls below 1 amp, finish with 2 amp constant current for 1 hour.

Rapid Recharge:Maximum voltage 15.6 volts (regulated), no current limit as long as battery temperature remains below 125°F (51.7°C). Charge until current drops below 1 amp.

Float Charge:13.2 to 13.8 volts, 1 amp maximum current, time indefinite (at lower voltage).

Strictly adhere to all limits.
The cyclic application is us. Jeff, these voltages are very aggressive for typical wet cells. In fact, too aggressive IMO and in the opinion of Lewco Electric in Newport Beach. For this reason having both types of batteries aboard compromises one or the other. Setting up your charging system for wet cells (14.0 ~ 14.2 volts) leaves AGM's undercharged. This was exactly my experience when I tried AGM's. At Catalina I'd charge and charge and charge only to see them coughing their last gasp in a very short time with modest load. The reverse is true too. Setting up your charging system for AGM's risks damage to wet cells charged with the same system due to over voltage. It's best to choose one type or the other, then give the banks the charging voltage they need.

About EI and AGM's

If AGM's are to be the choice and the charging system is set at 14.7 volts per Optima's specification, that's the voltage to your engine components at cruising RPM too. You had better run the EI current calculation again to be certain you don't start cooking coils.
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Old 12-02-2014, 12:51 AM
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I did not recommend combining battery types, nor do I think it's a good idea.

I did say that they have similar chemistry, and could be charged similarly. That's true, and the numbers you provide show this too - they can charge off an alternator at 13.8V indefinitely. Everything else is optimization and requires a smart multi step voltage regulator and temperature sensing - it's beyond this discussion.... The OP has a 35A stock alternator!

I would guess that most A4 owners do not have huge battery banks, big power budgets, or multi-step smart chargers. As such, I'm guessing that most of us are happy with the performance and cost of wet-cell lead acid, and single set-point voltage regulators. Heck, my boat was stock with only one start battery!

I would stick with the wet deep cycles and call it a day. Mine are Interstate from the local fisheries supply.
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Old 12-02-2014, 08:32 AM
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Jeff, I did not mean to imply you suggested mixing battery types, discussed it only because that was Tom's current situation although he has already said he's moving away from it.

However, charging AGMs indefinitely at 13.8 volts when Optima specifies 14.7 volts in cyclic applications is another matter and exactly what caused my poor battery performance when I tried them. You can certainly charge them at 13.8 volts but don't expect them to perform as advertised. It was an expensive and disappointing lesson.

Tom, I'm not saying you HAVE to go back to wet cells but if you decide to stay with AGMs please read Optima's specifications carefully. After trying them, I decided AGMs were not for me and went back to wet cells exclusively. Too bad because they're not as tall as wet cells and fit in places not possible before.
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Old 12-02-2014, 10:15 AM
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Sorry if I seemed prickly Neil, I should go to sleep earlier....

The key in this discussion is most of us are supply-side limited by an OEM single voltage regulator. And for most of us, based on our usage, that's fine. Especially, as you note, when the output is also driving the coil...

In fact, haven't we derived this rule of thumb?: 'If using a single alternator on a gas engine, then limit your battery selection (and charging voltage) to wet-cell lead acid'. Anything else will be more complicated and require some thoughtful engineering.

The Optima data suggests a number of acceptable charging voltage profiles, including alternator driven, shore power charger, and rapid recharge. Different profiles result in different charging times.

But to achieve optimal results without damage you need a smart multi-step regulator with temperature sensing at the battery. Calder is all about this: maximize charging and minimize engine run-time on a boat that's both power hungry and sailing most of the time.

Here's a Balmar smart regulator spec sheet example that shows a programmable voltage charging profile. My 55A API alternator from MMI can't do this.
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Old 12-02-2014, 10:29 AM
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Question

I must be a little slow but I cannot see any advantage in having a "starting" battery at all with an Atomic 4 which can easily start with a deep cycle 27, 29 or 31. Why waste space with a starter when another deep cycle will fit and be more versatile?
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Old 12-02-2014, 10:39 AM
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When you say 'starting', do you mean battery construction, or dedication/isolation for purpose?

If construction I'd agree, it really doesn't matter much with the A4, although a start battery is optimal. Dedication for starting still makes sense to me, with a fail-over combine to house.

Again, my boat came stock with one battery for start and house.
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Old 12-02-2014, 10:43 AM
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When you say 'starting', do you mean battery construction, or dedication/isolation for purpose?

If construction I'd agree, it really doesn't matter much with the A4, although a start battery is optimal. Dedication for starting still makes sense to me, with a fail-over combine to house.

Again, my boat came stock with one battery for start and house.
Both as to type and dedication; I switch all batteries separately and rotate "starting" duties.
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Old 12-02-2014, 10:56 AM
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The looming question: when is all this technology no longer worth the effort and expense?
AGMs cost considerably more, don't perform substantially better (IMO), require a significant change in the charging system to achieve anything near their advertising claims and with the new and improved charging system in operation it sends varying voltages to all the ship's and engine's components with potential for damage.

A while back I frequented a different - and aggravating - sailboat forum,. One of the three moderators was touting a new high performance Balmar hairpin wound alternator complete with the latest and greatest regulation. It was reported to offer good output at lower RPM and a bunch of other marvelous features and he'd be happy to sell you one (BTW, a clear violation of forum rules that he himself wrote, the rule against using the forum for business ventures or other personal gain but what'cha gonna do? He be da moderator. But I digress . . . . ).

It all sounded great up to the price point. $2300.00 uninstalled, batteries not included I don't recall if I posted it or just thought it but my knee-jerk reaction was, "You've got to be out of your mind! If I had that kind of dough to drop on a charging system it would be spent on solar long before a single fancy alternator."

P.S.
For accuracy, I think a new serpentine belt kit may have been included too. Whoopee!

edit:
The regulator matching the profile Jeff provided, necessary for proper AGM charging, the Balmar MC-614 is another $325.00. For a regulator. again.
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Originally Posted by hanleyclifford View Post
I must be a little slow but I cannot see any advantage in having a "starting" battery at all with an Atomic 4 which can easily start with a deep cycle 27, 29 or 31. Why waste space with a starter when another deep cycle will fit and be more versatile?
For the same reason I carry a spare tire in my car and my (former) motorcycle had a reserve type fuel tank valve. When it's needed, it's there. Big consumption is a game changer. I like my beer cold and my bilge dry and that means refrigeration. That alone is a 50AH daily hit. Over a simple three day Catalina weekend I can grind through the batteries pretty well so having an engine starter in reserve is peace of mind.
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Old 12-02-2014, 11:00 AM
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Talking

I'm with Neil on this one - KISS (and cheap, too).
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Old 12-02-2014, 11:06 AM
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The rational for a single house bank is in post #11 below. It assumes you have significant house loads in AH, and that you want to limit discharge to 50% for longevity. The optimal setup then is a big house bank, and a single usually much smaller start.

If your house loads are minimal, then two banks swapping between them for starting and house is fine. For many older boats, this was the 'upgrade' from a single battery to two, and the biggest load was the all-night anchor light which you forgot to turn off....
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