[bshock]

Hi All,

I posted a week ago about how I inadvertantly ruined my batteries by storing them improperly. So I inquired with my marina's service center about getting replacement batteries installed.

Since I'm still learning about batteries and how much is enough, I thought I'd share with everyone here what the service center is recommending.

To give a point of reference, I weekend cruise Western Lake Erie. My boat is a Beneteau 361 with a Westerbeke 30bThree diesel engine.

What is coming off the boat is one Group 24 House battery; and two 4D batteries, one of which is the starting battery.

The service center is recommending a Crown Battery 4D C4D1000 as the starting battery (1000 CCA), and a Crown Battery 24T-800 (75Ah, 550 MCA) as the house battery.

It seems to me that the 4D should work just fine as a starting battery, but I wonder if the Group 24 with the 75 Ah would be adequate as the house battery. It very may well be though. When we do anchor out, we'd only run the lights and water pump, maybe the microwave. We do not have AC, Heat, or a Fridge. Under way we'd use instruments (depth, wind, speed, and iphone chartplotter).

So what do you think? Would this set up be adequate?

 

[Brewgyver]

The cost difference between Group 24, 27 and 29 isn't a whole lot, and in terms of capacity, more is better. The higher the house battery capacity, the lower your depth of discharge should be, on an average outing. This will pay off in longer battery life.
I don't have a diesel, so I'll defer to others on the starting battery. For My Sweet Girl, I put in two group 29s for the house bank, and have a single 27 for starting, but then an A4 probably has much lower CCA needs than your diesel.

 

[capttb]

Sounds backwards, are you sure the start battery isn't the group 24 ? I believe that's how the French boats are usually set up, two 4D's for the house and a group 24 for start. The start battery is usually adjacent to the engine, short run to the starter.
We used to use a 4d to start 500 hp. diesel fire engines, doesn't take that much for a small diesel.

 

[bshock]

CaptTB, according to the spec sheets from Crown Batteries, the 4D quoted is listed as a starting battery; it doesn't even show amp hours. Whereas the 24T battery quoted is shown as a Marine Deep Cycle battery. So yes, I'm pretty sure that's how the service center is recommending the configuration.

 

[billyruffn]

It’s always good to size the batteries to the load they’re expected to deliver and the charging capacity of the system. You might want to figure out how many amps you burn between charges while at anchor overnight and while sailing with the instruments running. In theory, amps drawn x hours of use = amp hours. You probably don’t want to be discharging much more than 25-30% of the capacity to get long life from the batteries (naturally, you can discharge them to a greater extent, but it will shorten their life somewhat). Also, you want the charging system to deliver approximately 25%-40% of the amps the battery is rated for so that you minimize charging time. It’s something of a “Goldilocks” problem: you need to size it “just right” -- too few amp hours and you’ll shorten the battery life and be charging all the time. Too many amp hours and you need a big alternator to charge the bank in a reasonable amount of time.

Google “design of marine battery bank” or something along those lines and you’ll find several sites that will help you develop the amp hour budget you should need.

75 amp hrs sounds a bit light to me, but run the numbers yourself and see what it indicates for battery capacity.

 

[JimsCAL]

A 4D starting battery and a group 24 house battery makes zero sense. I would suggest the 4D be a deep cycle used for both house and starting and the Group 24 becomes a 100% reserve. A battery combiner would insure that the reserve battery is always fully charged.

 

[mitiempo]

...the 4D quoted is listed as a starting battery; it doesn't even show amp hours. Whereas the 24T battery quoted is shown as a Marine Deep Cycle battery. So yes, I'm pretty sure that's how the service center is recommending the configuration.

That doesn't make it the right way to do it though.

I agree with the others. A group 27 will start your engine easily. An engine start needs less than 1 AH. The amp hours are needed for house loads. One group 24 for house loads is ludicrous.

I would suggest looking at 6 volt golf cart batteries, either 2 in series (or series parallel if you choose 4) as they are the best value in batteries as well as being easier to move around than 4D batteries. 2 golf carts in series will give you about 220 AH, double that if you get 4.

They are the choice of many for house banks.

 

[bshock]

Thanks All. I'll take what you've said and move forward based on that.

 

[capttb]

bshock, The proposed batteries should work fine for your purposes, just atypical as a majority are trying to maximize their house banks. Without a fridge (or inverter) a 27 will easily last 3-4 days, and a 4D will have a lot of reserve starting power. Different ways to skin a cat, a racer or economist would suggest 2 or 3 group 27's to save weight/money. Casual (?) Cruiser would like 2 4D's for the house and a 27 to start, Extreme (?) off the hook types like 6 volts for greater house capacity, and a smaller start bank.
Usual thinking is the start bank only has a very short duration high draw which is quickly recharged by the engine, most of your sailing time or anchor/mooring will be low draw/long term off a house bank. As an old friend used to say "It's whichever what you like, However."

 

[MarkSF]

The best way to approach this problem is with a serious estimation of your power needs. Please note that you can actually only realistically use 35% of the batteries Ah rating - it might not get charged past 85% with typical periods of charging from an engine, and it is best not to discharge past 50%.

I typically use 20-30 Ah on an overnight stay, and that's without anything powerful like a microwave. That could be using as much as 100A, so use it with care! An incandescent anchor light alone could use 10 Ah overnight.

My house bank is two group 24s. That gives me a useful capacity of 70 Ah.

 

[MarkSF]

PS, might be good to find another service centre.

 

[Alex W]

It can be cheaper in the long run to make the boat power efficient then to run these massive house battery packs. We have a very model house battery system of two group 24 batteries (useful capacity is 80AH). I don't use an inverter or have a fridge. All lights are LEDs and we use power efficient laptops and tablets on board. We have a good power monitor and it is extremely rare to see a draw of more then 2A, in a typical 24 hour period cruising we use less than 20A. That is easily replaced by the alternator when motoring in out of ports and by our 30W (2.5A) solar panel. During daytime most of our power consumption is going to navigation electronics.

If I had kept our boats incandescent lights I would have had to run a 4 GC2 battery bank to get similar performance. I have nowhere to keep that large of a battery system on our boat and the $300 that we'd have spent on the 2 additional batteries paid for the majority of the upgrade to LED lighting.

A good battery monitor is a very useful tool. Only by analyzing your system can you really figure out how much battery you need.

 

[bshock]

Thanks All, I did some more research yesterday and found that the Interstate Battery store has 4D deep cycle batteries for about $200 each, with more than 1300 CCA and about 230 Ah. So I think I'm going to get two of those.

Thanks so much for all your help, advice and insight.

 

[Maine Sail]

Thanks All, I did some more research yesterday and found that the Interstate Battery store has 4D deep cycle batteries for about $200 each, with more than 1300 CCA and about 230 Ah. So I think I'm going to get two of those.

Thanks so much for all your help, advice and insight.

A 4D or 8D short of a diesel sport fishing boat with 600HP needing CA's is beyond me..

I will post this again, as I have before...

You can't compare an Interstate 4D cranking battery to a good quality true deep cycle battery. Ignore the sticker, they are LYING TO YOU when they tell you it is a deep cycle battery. This is akin to comparing the reliability of a Honda or Toyota to a Renault Le-Car, IMHE. Those "types", deep cycle vs. starting batteries, are not even in the same class of battery. The Interstate SRM-4D is made by Johnson Controls/JCI for Interstate. Interstate is a "sticker" company these days and JCI is really the Yugo of batteries, not particularly the best brand but in some markets they remain somewhat competitive. Other then their GC2 6V's I have not seen their batteries do much of anything, longevity wise, in the marine market.

I actually called interstate a few years ago to try and find out the Ah rating and plate thickness of one of their batteries. What a freaking debacle. Even their tech support had no clue. I got three different answers when I asked about the 20 hour Ah rating. Don't even attempt to get a Peukert's exponent..... uke

If you have a battery monitor you need to know the precise 20 hour Ah rating or it will not work correctly. Buying a battery that lacks a 20 hour rating is a crap shoot without knowing the accurate specs, and Interstate refuses to publish a 20 hour rate. Even when they do the Ah capacity is NOT accurate, I know this because, I have tested three or four relatively new but broken in Interstate batteries and none of them could deliver the "claimed" 20 hour capacity under well controlled test conditions. Course with three differnt answers from three differnt people in tech support who knows what the "real" capacity is...? Probably why they refuse to publish 20 hour ratings.

Here's a good general rule of thumb. If the manufacturer does not publish a 20 hour Ah rating the battery is often not a true deep cycle battery, but then again Interstate does not market this as a true deep cycle battery they market it as a hybrid deep cycle/cranking battery. It is a truck starting battery, nothing more. The "sticker" does not change anything physically inside the battery...

There are however exceptions to the 20 hour rating guidance. NAPA sells the SAME deep cycle 12V batteries that West Marine does but NAPA does not publish the Ah rating in their specs for the battery. A simple call to the manufacturer, Deka/East Penn, and you know this. East Penn actually has a clue because they are an actual manufacturer of batteries not just a company that slaps a sticker on someone else's battery. East Penn also sells batteries to "sticker" companies like West Marine, NAPA, Duracell, O'Rielly Auto etc. etc....

Interstate labels it as a dual purpose battery or "deep cycle/cranking" these are hybrid batteries at best, that attempt to do both but almost always miss the mark when put into a true deep cycling application like a boat. They all start life on the same assembly line and at the end get a truck cranking battery sticker or a "marine deep-cycle" sticker.. The real and only value in a battery is how many cycles you will get and in deep cycling applications 4D's and 8D's fall flat when compared to a true "deep cycle" design...

One of the only true 4D deep cycle batteries I know if is the Dyno 4Dd (the small d designated deep cycle) not to be confused with the Dyno 4D which is for starting. This battery has an Ah rating of 180 Ah's and cost $268.00. Like many true deep cycle, thick plate batteries, they do not publish a CCA value. I have not seen any 4D actually deliver 230 Ah's.. That is 8D range.

If you have the physical height a set of 6V batteries in series or series parallel will last longer & give more cycles.

In the past Interstate has had some good batteries in its line up. Interestingly enough the old U2200 6V used to be made by US Battery and was an EXCELLENT, top quality battery. Now days that battery it is made by JCI. I guess paying for the quality of the US Battery, to put the Interstate name on, left them with little margin so they outsourced it to a less expensive vendor, namely JCI.

That being said any 6V battery, good quality or lower end brand, will almost always have thicker plates than a dual purpose flooded 4D and thus last longer in deep cycle applications. I've yet to see an industrial floor scrubber machine or golf cart with 4D's or 8D's.. There is a reason for that. 6V batteries are also taller by design so sulfation can be shed off the plates and fall to the bottom of the case during equalization. A shorter battery fills up with shed plate junk faster than a shorter one. As you get into even thicker plate deep cycles like the L-16 case they are even taller.

If you have the room (height) for two or four 6V batteries they are always the better value. In the end they will cost less on an Ah/$$$ and $$$/cycles basis.

My Synopsis of Wet Cell Batteries by Grade/Quality:

Top Tier:

Rolls

I intentionally left a space here because the Rolls batteries are significantly more top tier than US Battery or Trojan..

Trojan
US Battery

Second Tier:

Dyno
Crown
Superior
Deka/East Penn

Third Tier:

Johnson Controls / Private Labels
Exide
Interstate (most of these are made by Johnson Controls)
Various Private labeled batteries


I've not even touched on getting a hernia or needing back surgery from the 4D's...

Bottom line there are only a handful of true "deep cycle" batteries in a 4D case and those are:

Dyno 4Dd Flooded
Lifeline AGM 4D
Deka GEL 4D

Every other 4D is a starting battery or "hybrid" at best.. Don't be fooled by the "sticker" as you will not see the same cycle lofe as a true deep-cycle battery.. Stickers don't make batteries "deep cycle" plate thickness and design does......

 

[bshock]

Wow, Maine Sail, thanks for that. I did not know that about Interstate batteries. Back to the drawing board, I suppose. I did talk to the Crown Battery rep today and he suggested Crown's 4D "deep cycle," part number SD4D200, in their Severe Duty line. I'll have to find out what those cost.

Who knew buying batteries would be so confusing! One great thing about this, though, is that I'm learning a heck of a lot about boat batteries, for which I'm very greatful to all of you.

 

[mitiempo]

Your best bet is to ignore 4D batteries totally, whatever brand or designation on the label, or whatever a rep tells you.

As both Maine and I have posted 6 volt golf carts are the best value, the longest lasting deep cycle batteries for anywhere near a reasonable price.

 

[Maine Sail]

Wow, Maine Sail, thanks for that. I did not know that about Interstate batteries. Back to the drawing board, I suppose. I did talk to the Crown Battery rep today and he suggested Crown's 4D "deep cycle," part number SD4D200, in their Severe Duty line. I'll have to find out what those cost.

Who knew buying batteries would be so confusing! One great thing about this, though, is that I'm learning a heck of a lot about boat batteries, for which I'm very greatful to all of you.

The Crown 4D is NOT A DEEP CYCLE BATTERY!!!!! Crown tech support will openly tell you this, they are HONEST. Ah ratings and stickers DO NOT translate to real world cycle life..

I do not know how to be any clearer on this. If you want a battery for deep cycling applications DO NOT BUY A FLOODED 4D or 8D battery.

No one but Dyno makes a true 4D deep cycle flooded battery and I honestly question how many cycles you would get out of the Dyno compared to one of Dyno's GC2 golf cart batteries..


The last company building a true 4D deep cycle was US Battery and they dropped them approx 7 years ago. Dyno "claims" to make one but who knows.

Expect about HALF the lab rated cycles out of the Crown 4D as you would get from a Crown GC2. Crown makes GC2 batts in 205Ah, 220Ah, 225Ah, 235Ah and 240Ah sizes. The case size on all those GC2's is identical.

4D = 8.25 Wide X 21" Long

GC2 = 7.13" Wide X 10.25" Long

2 X 6V = 7.13" Wide X 20.5" Long

The 6V batts are about .75" taller. If you have that extra .75" in height it is a NO BRAINER to drop two 6V batts in place of a 4D....

The only reason builders install 4D or 8D batteries is COST SAVINGS. There is ZERO benefit to you the end user and only negatives to using a 4D or 8D batteries in a cycling application...

 

[TakeFive]

This is a great tutorial. I know it has been posted before, but good to review again.

For those of us with little boats, could you please add some details on Group 24 form factor? Which group 24 deep cycle batteries are truly deep cycle, and which ones are imposters?

 

[bshock]

Thanks again, Maine Sail. I misunderstood about the Crown (or any other 4D's), not actually being deep cycle. Let me ask you this, would two 6 volt deep cycle "golf cart" batteries when joined in series (or is it parallel to make them 12V?), be a good starter battery? The way my existing 4Ds worked is that one of them was hooked up to the starter.

 

[Maine Sail]

This is a great tutorial. I know it has been posted before, but good to review again.

For those of us with little boats, could you please add some details on Group 24 form factor? Which group 24 deep cycle batteries are truly deep cycle, and which ones are imposters?

Most all are all "imposters" including Trojan 12V G-24, G-27 & G-31... Some will give more "cycles" than others in these group sizes but none compete directly with a GC2 in terms of cycle life.. You are not just buying Ah capacity you are buying cycle life. There are 12V golf cart batteries such as the Trojan T1275, and they do have the same cycle life as a 6V, but they are also taller, like the 6V, and a built to use the same plates as a GC2 battery. G-24, 27 & 31 batteries simply do not have the plate thickness a GC2 battery does.....

For example in the Deka / Sea Volt / West Marine line you have starting, dual purpose and deep cycle G-24, 27 & 31 12V batteries which all share the same case. However they are only really deep cycle when compared to the starting or dual purpose batteries which share the identical case. They are not "deep cycle" when compared to the GC2 or other true deep cycle batteries..

Here's the data across the Deka / East Penn / West Marine line up:

Flooded Batteries - Group 24, 27, 31 & 6V GC2

12V Starting - Cycles to 50% = Not Rated
12V Dual Purpose - Cycles to 50% = 200
12V Deep Cycle - Cycles to 50% = 350
6V Golf Cart - Cycle to 50% = 700-1000


*Note: The above are LAB RATED cycles. Expect at least 50% less in the real world..


As you can see the 12V "deep cycle" battery is only a "deep cycle" when compared to the starting or dual purpose batteries it shares a case with. If you absolutely must buy a 12V G-24, 27 or 31 buy the deep cycle version. In amny cases this is all that will fit. It is easy to see that these are NOT deep cycle when compared to a real deep cycle battery.

The only ones that have lab rated cycles the same or close, to their own brands 6V batteries, are Lifeline and the US Battery DCXC 12V series (at least those are the claims). I know of no other brand that will rate their G-24, G-27 or G-31 at even half the cycles of their GC2 6V batteries. The Deka / East Penn / WM product is less than half...