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Best Battery for '87 Traditional Layout

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sethp001
Mainsheet C-25 Tech Editor

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814 Posts

Initially Posted - 05/22/2012 : 16:57:53

I discovered over the weekend that the two identical Marine Maxx batteries that came with my boat are dead. They're 5 years old to the month.

They were installed in the battery compartment under the starboard settee. They appear to be Group 29 size batteries.

I have the two battery selector dial switch.

So I've been researching batteries. It looks like I may be able to fit a single larger battery in that compartment.

I have an electric start outboard motor that I can start by hand. With that in mind, is there any advantage to having two batteries vs. one larger battery? Redundancy?

What's the largest group size battery you have installed in that compartment?

What do you think is the best battery setup? I'm interested in max AMHs.

Seth
"Outlier" 1987 Catalina 25 SR/SK/Traditional Interior #5541
"Zoo" 1977 Morgan Out Island 30
"Nomad" 1980 Prindle 16
"Lost" 1988 Catalina Capri 14.2 (sold - yay!)
"Marine Tex 1" Unknown Origin POS 8' Fiberglass Dinghy
https://whichsailboat.com/2014/07/27/catalina-25-review/

Edited by - sethp001 on 05/22/2012 17:01:34

Joe Diver
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Response Posted - 05/22/2012 : 17:08:24

I have 2 group 31 marine deep cycles. 105 aH each wired parallel. 210 aH in the bank.

Edited by - on

WesAllen
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222 Posts

Response Posted - 05/22/2012 : 18:33:42

I also have 2 group 31 (AGMs) that fit in very nicely.

Wes

Edited by - on

Dave5041
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Response Posted - 05/22/2012 : 19:24:52

Redundancy is the primary advantage of 2 batteries since we can pull-start our outboards if necessary, handling is the secondary. A backup for nav/anchor lights and radio can be important. You lose that with a large, single battery, but you could pack more amp hours in the space since you would lose the weight and bulk of one battery case. Measure the space and see if you can find a single battery above 210 AH that fills it. Good luck getting a battery that big in and out of the boat. Incidentally, 210 AH only puts 105 AH in the bank, the other 105 are in an IRA if you value battery life. AGM may give you a slight improvement in AH if $ aren't an issue, but remember that 10 extra AH for $50 more is $5 an AH. My Walmart deep cycles typically last 7 - 10 years with proper care.

Edited by - on

Joe Diver
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Response Posted - 05/23/2012 : 06:21:04

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Dave5041
 210 AH only puts 105 AH in the bank, the other 105 are in an IRA if you value battery life.
<hr height="1" noshade id="quote"></blockquote id="quote">

It's my understanding that with marine deep cycles, you can exceed the 50% rule because they're designed for deep discharge cycles, 80%. Using that, I have 168 aH in my bank before discharging too much.

Edited by - on

Dave5041
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Response Posted - 05/23/2012 : 13:48:54

I know that 80% is often claimed, but I get 7-10 years out of modestly priced batteries and will stick to 50%.

Edited by - on

islander
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3994 Posts

Response Posted - 05/23/2012 : 15:55:37

Joe Divers set up with the group 31's is about all your going to fit in the battery compartment on an 87 ( just aft of the water tank). The next size up would be a 4D at 198Ah or an 8D at 245Ah but neither of these will fit. Unless you want to find a different spot I would go with the 2 31's giving you 210Ah.

Edited by - on

Jefffriday
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198 Posts

Response Posted - 05/23/2012 : 16:13:12

Just got the Wal Mart 31's for my boat, best pricing/ah by far, the 50% rule and a conditioning cycle now and then and you will get much better life.

Edited by - on

Joe Diver
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Response Posted - 05/23/2012 : 17:10:53

When I replaced my house bank, I did so with the 50% rule in mind, but the 80% gives me a third day should I need it.

Edited by - on

jrchase11
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Response Posted - 05/23/2012 : 17:42:18

I have two 105ah (210 bank)Stowaway's from Academy sports and I am pretty sure they are Group 27's. I have two different compartments under the starboard settee and am pretty sure I cannot fit any larger of a battery in each compartment (because I purposely bought the biggest batteries that would fit in the compartments).

Nigel Calder recommends using 50%. Discharging to 20% will yield roughly half of the cycles as 50%.

Edited by - on

Dave5041
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Response Posted - 05/23/2012 : 18:34:02

<blockquote id="quote">quote:<hr height="1" noshade id="quote"> gives me a third day should I need it<hr height="1" noshade id="quote"></blockquote id="quote">

My feeling exactly. Just like an IRA, it's there if you need it, but there is a penalty for early withdrawal.

Edited by - Dave5041 on 05/23/2012 18:34:40

pfduffy
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317 Posts

Response Posted - 05/24/2012 : 10:25:38

I'm going to hijack this thread and display my battery ignorance (or perhaps general ignorance) with a question on charging. Currently, the only charging capability I have on my boat is the alternator on my shiny new Tohatsu outboard (6 amp?). I believe, but have not actually calculated, that I use very little of the battery capacity - VHF radio, depth finder and very infrequently, nav lights. I run the motor about an hour each time I sail. Am I doing damage to the battery? Is there something I should be doing to ensure that the battery lasts longer? Do I need to go through the trouble of installing shore power and a battery charging system?

Edited by - on

NautiC25
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957 Posts

Response Posted - 05/24/2012 : 10:36:54

I love this chart:

Came from this page: http://www.marxrv.com/12volt/12volt.htm

I plan to set my alarm at 50%, knowing I'll have another 10% to safely use.

Edited by - NautiC25 on 05/24/2012 10:38:16

Stu Jackson C34
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Response Posted - 05/24/2012 : 11:13:01

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by pfduffy
 I'm going to hijack this thread and display my battery ignorance (or perhaps general ignorance) with a question on charging. Currently, the only charging capability I have on my boat is the alternator on my shiny new Tohatsu outboard (6 amp?). I believe, but have not actually calculated, that I use very little of the battery capacity - VHF radio, depth finder and very infrequently, nav lights. I run the motor about an hour each time I sail. Am I doing damage to the battery? Is there something I should be doing to ensure that the battery lasts longer? Do I need to go through the trouble of installing shore power and a battery charging system?
<hr height="1" noshade id="quote"></blockquote id="quote">

Try http://www.amplepower.com/tech_docs/index.html download the Ample Power Primer (tech tab).

Leaving batteries chronically undercharged reduces their life dramatically. Solar would be your best bet if you're a weekender.

Edited by - Stu Jackson C34 on 05/24/2012 11:17:33

redviking
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Response Posted - 05/24/2012 : 20:52:27

Best Battery? As many as you can afford... on My C25 I had five batteries, three cheap 15 W solar panels and a small Honda generator and one on the motor. Juice is ling if you cruise and/or spend the summer on a ball.

I have learned a lot about batteries over the past 5 years and particularly when I had to swap out four heavy Rolls 6 volt batteries on My C&C 39... The batteries were 3 years old but under a 7 year, no prorated stuff. They shipped my old batteries back to Nova Scotia and found 3 of them were defective because the lead did not connect properly all over inside. Imagine a Kmart battery performing flawlessly while cruising full time, i.e docks were rare, for 3 years before no holding a charge properly and being deemed defective?

It's all in the the thickness of the plates. Deep cycle batteries are designed to be discharged down as much as 80% time after time, and have much thicker plates. The major difference between a true deep cycle battery and others is that the plates are SOLID Lead plates - not sponge. This gives less surface area, thus less "instant" power like starting batteries need.

Note the difference between a Rolls Battery and a NAPA Battery in terms of weight. Same size, same voltage.

Part Number: BAT 8143
Product Line: NAPA Batteries
Attributes:

Battery BCI # : BCI #GC2
Battery Height : 11 3/8"
Battery Length : 10 1/4"
Battery Voltage : 6 Volt
Battery Warranty in Months : 24
Battery Width : 7 1/8"
Battery Posts Type : Offset Post w/ Vertical Stud Post
Battery Weight : 60.5 lbs
Wet or Dry : Wet

http://www.napaonline.com/Catalog/CatalogItemDetail.aspx?R=NBE8143_0213498931

Now the Rolls:

EIW 250
250
336
758
948
10 3/16"
7 1/8"
11 2/5"
79 lbs

That's a 19lb. difference!!! And the NAPA battery is considered a good one by most cruisers.

I found this on the net:

These are some typical (minimum - maximum) typical expectations for batteries if used in deep cycle service. There are so many variables, such as depth of discharge, maintenance, temperature, how often and how deep cycled, etc. that it is almost impossible to give a fixed number.

Starting: 3-12 months
Marine: 1-6 years
Golf cart: 2-7 years
AGM deep cycle: 4-8 years
Gelled deep cycle: 2-5 years
Deep cycle (L-16 type etc): 4-8 years
Rolls-Surrette premium deep cycle: 7-15 years

Other lessons learned. 60% is plenty, charge it up. The more batteries you have in a bank improves your odds of never dipping below 60%. I like having two banks with two batteries each and then having a start battery. (Overkill on a C25 perhaps, but that is what I carried on mine, and yes they were kmart batteries and I replaced them many times over.)

AGM is typically the choice cruisers make for a start battery.

Replace one in a bank, more than likely you should replace the other as well. This is why it is good to have two banks. You can isolate a battery problem before it damages all of the others, AND hopefully your other bank is better. Towards the end before I replaced the Rolls, I could only run off of the one bank that had a perfect battery.

After charging to full, wait a bit and watch the voltage drop. An autocharger is a nice trick for this reason, or charge them again to really top them off.

Always charge first and then add distilled water.

And finally, calculate the Amp Hours used, anchor light, interior, running, radio, VHF, depthsounder, plotter, etc. and buy accordingly. It will also help you calculated how much you are putting back into the bank with solar or the alternator on the engine. My neighbor has a C25 with three solar panels and a windgen.

But i like to live large on a boat. More juice means never having to worry or have to hit a dock to charge up.

sten

Edited by - on

OLarryR
Master Marine Consultant

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USA
3370 Posts

Response Posted - 05/25/2012 : 04:23:29

Dave,

It's hard to argue with getting 7-10 yrs out of a set of Walmart batteries whether one goes by 50% or 80%. If it ain't broke, then don't fix it !! When it comes time to replace my batteries, I will have to consider the Walmart ones against getting the same flooded West Marine batteries presently on my boat. It will be basically a cost comparison since I generally have light loads, recharge with a 20Watt Solar panel and occasionally a long run on the outboard helps as well and I so far have about 7 1/2 years on present batteries.

Pat - The fact that you utilize the battery for light loads and when you use your boat you recharge approximately 1 hr with the outboard each time is pretty good but it's more complicated as to whether that is enough to maintain your battery in a fully charged or close to fully charged state to get the longest life out of the battery. Here are some things to consider:

Generally, as the batteries get charged, there are bigger gains when initially charging. The charging is not necessarily proportionate in the amount of time to recharge as it closes in on the fully charged state. It takes a bit longer to get from 90-100% charged than to get from 80-90% charged. If you frequently sail say 2-3 times a week, then your outboard may be enough to maintain the battery in a fully charged state depending on the recharging capability of your outboard, having it run at moderate speed for an hour each time and at least 2-3 times a week utlilizing only light loads each week.

Here's the other part to consider if actually figuring out hours recharging vs discharging. A battery will normally discharge just sitting around all day and not being used at all. It will lose ~ .4 amps/day during the summer months and ~ .25 amps/day during the winter months. So, if you only use the boat once a week in the summer and do not use any loads on the battery at all not even for starting the outboard, you will be still losing approximately 3 amps/week. If you charge with the outboard 1 hour each week and the outboard is run at a slow speed for half that time, then it will be first of all, not recharging at it's max charge rate and if the recharging ideally was at 3 amps/hr, then you would recharge the battery at much lower due to sometimes at a slower outboard speed reducing recharge rate amd also the fact that the last 10-20% recharging of a battery takes longer. Then add the fact that you occasionally will use the battery for miscellaneous loads, then you can see how the battery may not get fully recharged by an ouytboard even if run for 1 hour each time you sail. Then again, if you sail frequently, it may be enough.

Many of us may not run the outboard for an hour each time we sail but may sail frequently. In this instance, a solar panel helps tremendously for recharging a battery since it may only recharge at a very low amp rate but for many hours each day for perhaps 4-5 days a week. A solar panel also does not always charge at it's max amp rate. In fact, it rarely charges at the ideal rate. My solar panel ideally pumps out 1.2 amps/hr but in reality I can count on between .4 and .8 amps for about ~ 5 hours a day and for about 4-5 days a week for a max charging of 10-11 amps/week. I have two batteries discharging about 6amps/week with no loads, so my 20 watt panel is just enough to keep me fully charged as I am a light load user. (My outboard also perhaps helps a bit for the short time I generally use it.) A 30 watt or larger panel would be needed if I were a heavy load user.

Edited by - OLarryR on 05/25/2012 04:26:55

GaryB
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4275 Posts

Response Posted - 05/25/2012 : 05:18:13

Joe - What brand of batteries do you have?

Joe & Jeffriday - Are you Group 31's in battery boxes are just placed side by side in the battery compartment?

Anyone - How can you tell the AH rating of a battery? I'm looking at Interstate batteries and they list reserve capacity but I don't see anything on AH ratings.

Edited by - on

redviking
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Response Posted - 05/25/2012 : 08:36:11

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by GaryB
 Joe - What brand of batteries do you have?

Joe & Jeffriday - Are you Group 31's in battery boxes are just placed side by side in the battery compartment?

Anyone - How can you tell the AH rating of a battery? I'm looking at Interstate batteries and they list reserve capacity but I don't see anything on AH ratings.
<hr height="1" noshade id="quote"></blockquote id="quote">

The list shows all the data... But first here is a primer on the difference between Marine Cranking Amps and Cold Cranking Amps and how long the battery will last under a 25 amp load.

http://www.interstatebatteries.com/cs_eStore/content/product_info/marine_r.asp

Now here is and example of the data Interstate provides.

http://www.interstatebatteries.com/cs_eStore/content/product_info/marine_f.asp

sten

Edited by - on

skrenz
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USA
351 Posts

Response Posted - 05/25/2012 : 08:41:45

It all comes back in a fog to me

I was asking the same question a couple of months ago and it appears that the answers, at least about AGM batteries were different.
You can see the posts and opinions here:
http://www.catalina-capri-25s.org/forum/topic.asp?TOPIC_ID=24580& SearchTerms=battery

Edited by - on

Joe Diver
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Response Posted - 05/25/2012 : 10:26:48

I can't remember...I bought them at Academy on sale. They're both marine deep cycles...matched....same manufacture date and all. 105 aH each. rating printed on the label on the top of the batteries. I found that starting batteries list cold cranking amps, marine deep cycles list amp hours. This is not always true, but seemed to be the trend.

No battery boxes, they both sit end to end in the starboard compartment. Very snug fit, but they do fit. Heavy suckers too.

Since I sail on a lake and the chances of going upside down are exceptionally slim, flooded cells are fine.

I use an Optima in my Jeep though. Chances of going upside down are much higher.

Edited by - on

GaryB
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Response Posted - 05/25/2012 : 21:21:37

Well, I went with Interstate SRM-27's. I could not find the amp/hr rating anywhere but the reserve capacity is 160 each for a total of 320.

If I want to hook them up in parallel so I get 12 volts and all 320 amps of reserve capacity I go positive to positive and negative to negative, correct?

I have a OFF, 1, 2, Both switch. Does that make any difference in the waqy it's wired to get the full amps?

Edited by - on

Davy J
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Response Posted - 05/26/2012 : 05:16:19

<blockquote id="quote">quote:<hr height="1" noshade id="quote">If I want to hook them up in parallel so I get 12 volts and all 320 amps of reserve capacity I go positive to positive and negative to negative, correct<hr height="1" noshade id="quote"></blockquote id="quote">

Once connected this way, your battery selector switch will become non-functional. It will only turn the bank on or off.

Edited by - Davy J on 05/26/2012 05:19:44

islander
Master Marine Consultant

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Response Posted - 05/26/2012 : 06:10:40

They claim 96Ahrs
<blockquote id="quote">quote:<hr height="1" noshade id="quote">Interstate SRM-27 Deep Cycle Marine & RV Battery 600 CCA

SKU: SRM-27 (Item# 24024)

Brand: Interstate

OEM - 100% New Genuine Original.

Interstate SRM-27 is a deep cycle and high cranking power battery for marine and RV applications. It contains an unique new chemistry for robust seasonal use and added charging and is backed by Inter...see more

Specifications

Chemistry

Conventional (Wet Cell)

Voltage

12.0 V

Capacity

96 Ah

Rating

1152 Whr

CCA

600

Cell

6 cells

Connector

Marine

<hr height="1" noshade id="quote"></blockquote id="quote">

Interstate SRM-27 Deep Cycle Marine & RV Battery 600 CCA

SKU: SRM-27 (Item# 24024)

Brand: Interstate

OEM - 100% New Genuine Original.

Interstate SRM-27 is a deep cycle and high cranking power battery for marine and RV applications. It contains an unique new chemistry for robust seasonal use and added charging and is backed by Inter...see more

Specifications

Chemistry

Conventional (Wet Cell)

Voltage

12.0 V

Capacity

96 Ah

Rating

1152 Whr

CCA

600

Cell

6 cells

Connector

Marine

[/img]

Edited by - on

GaryB
Master Marine Consultant

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4275 Posts

Response Posted - 05/26/2012 : 06:53:24

Davy - Thanks for the info. Putting the battery selector on both wouldn't give you the combined amp/hrs?

Thank you Scott. Where did you fnd that info. I looked all over Interstates site and could not find thw rating. Even the people at the RV store couldn't find anything.

So what is more important the Amp/Hr rating or Reserve Capacity?

Edited by - on

Davy J
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Response Posted - 05/26/2012 : 07:01:41

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Putting the battery selector on both wouldn't give you the combined amp/hrs?<hr height="1" noshade id="quote"></blockquote id="quote">
If you wire the batteries normally to the selector switch and then set the switch to "both", you would get the same effect as wired in parallel. The downside is, if you discharge one battery, say set to "one", then later switch to "both", the discharged battery will bring the other one down quicker. I have my batteries in parallel and running on the switch as battery "one".

Edited by - on

GaryB
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Response Posted - 05/26/2012 : 07:21:23

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Davy J
 <blockquote id="quote">quote:<hr height="1" noshade id="quote">Putting the battery selector on both wouldn't give you the combined amp/hrs?<hr height="1" noshade id="quote"></blockquote id="quote">
If you wire the batteries normally to the selector switch and then set the switch to "both", you would get the same effect as wired in parallel. The downside is, if you discharge one battery, say set to "one", then later switch to "both", the discharged battery will bring the other one down quicker. I have my batteries in parallel and running on the switch as battery "one".
<hr height="1" noshade id="quote"></blockquote id="quote">
Back when I had two batteries I always ran it on both. My motor doesn't have a charging system so there really isn't any reason for me to run on one battery. Unfortunately one battery over-heated one night I had to tear the system apart in a hurry in the middle of the night and I don't remember how it goes back together.

If I wire it normally do I just tie the two negative posts together along with the negative wire form the switch and use the separate red leads from the switch to each battery?

Edited by - on

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