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britinusa
Web Editor

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USA
5404 Posts

Initially Posted - 10/02/2011 : 09:34:30

Reading several unrelated threads... one about moving the batteries to the bow and another Battery Scare, made me think deeper about our impending battery replacement.

Our batteries are probably about 4 years old. We replaced them both after a charger took them out. At the time we replaced the charger with the same brand and since found that brand has issues when running any 12v device while charging. Now the batteries do not hold their charge and need recharging within a few hours even with everything turned off.

No stray currents found in the wiring (zero amps if all 12v electric panel switches off and solar panel covered.)

A couple of months ago, we upgraded our Battery charger (which had been disconnected since finding it was a problem) with a brand new MasterVold 12/20-3 although we only have 2 batteries.

So it's time to replace the Batteries (especially after reading the 'Battery Scare'.)

I'm going to keep them 'trunk', we have a 2nd water tank under the V-Berth, so no room. And we're both skinny enough (just

) to get out of the Forward Hatch.

Now to figure out which type of battery to get (deja vu).

We have a Nissan 9.8hp Electric Start outboard.

Searched, but cannot find the cranking amps of the engine starter.

Reading up on the Deep Cycle / Starting battery types, I'm not sure which type to purchase.

Input?

Paul

Joint Decision. (Sold)
PO C250WB 2005 Sail # 841.

Moved up to C34 Eximius

Updated August 2015

Edited by - on

Stinkpotter
Master Marine Consultant

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Djibouti
9017 Posts

Response Posted - 10/02/2011 : 11:00:01

Your 9.8 hp motor doesn't need a "starting" battery (designed for short, heavy draws)--that's for cranking automotive type (including marine) engines. I'd suggest marine deep-cycle batteries like [url="http://www.defender.com/product.jsp?path=-1|328|51495|306219&id=777510"]this one[/url]. WM and others probably have comparable ones.

Edited by - on

delliottg
Former Mainsheet C250 Tech Editor

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USA
4479 Posts

Response Posted - 10/02/2011 : 11:49:49

Paul,
I replaced our single battery a while back with two Optima deep cycle batteries. [url="http://www.catalina-capri-25s.org/forum/topic.asp?TOPIC_ID=20505&SearchTerms=optima"]Thread here[/url].

I originally planned to move them to the bow, but for now, I don't really see the need.

So far we've had no problems with them and the install, while a bit frustrating due to the weight of the batteries, was worth it. The aluminum hold downs I made to attach the trays to the battery box can be fashioned with hand tools (drill & hacksaw).

I think the two batteries cost me in the neighborhood of $300 at Costco.

Edited by - delliottg on 10/02/2011 11:50:13

islander
Master Marine Consultant

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3994 Posts

Response Posted - 10/02/2011 : 13:54:41

I second Dave, Use deep cycle. My choice of brand would be Deka(East Penn).These are the people who make West Marines battery's, We also use them in all the heavy equipment at work. I have one group 31 deep cycle in the boat.

Edited by - on

Dave5041
Former Mainsheet Editor

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USA
3754 Posts

Response Posted - 10/02/2011 : 19:07:24

Replied on the "Battery Scare" post. I agree with the pure deep cycle and I buy at Walmart.

Edited by - Dave5041 on 10/02/2011 19:08:04

Steve Milby
Past Commodore

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5853 Posts

Response Posted - 10/02/2011 : 20:11:04

The best wet cell deep cycle marine battery I ever had was the Interstate brand marine battery that came with my C25 when it was new. I have two of them on my present boat, primarily powering the refrigeration. The battery charger has been keeping them topped off continuously all summer. They cost about $100. each.

Edited by - Steve Milby on 10/02/2011 20:30:14

GaryB
Master Marine Consultant

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4275 Posts

Response Posted - 10/03/2011 : 17:35:06

I used to use Interstate batteries in my SeaRay and they always lasted for years and you can get warranty on almost every street corner. They have dealers everywhere.

Edited by - on

Stinkpotter
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Djibouti
9017 Posts

Response Posted - 10/03/2011 : 18:04:10

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Steve Milby
 The best wet cell deep cycle marine battery I ever had was the Interstate brand marine battery...<hr height="1" noshade id="quote"></blockquote id="quote">Interstate makes a lot of private brands, including, I believe, Defender's. Their trucks seem to make daily visits to marinas around here. As I said somewhere else, "marine" batteries generally claim to have heavier-duty plates than auto batteries, based on the assumption they will take deeper discharges and get less frequent charges. So it will cost a little more than a battery at Cosco or Wallymart. Ya payz yer money and ya takes yer choice.

Edited by - on

TakeFive
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2270 Posts

Response Posted - 10/05/2011 : 05:40:24

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Stinkpotter
 Your 9.8 hp motor doesn't need a "starting" battery (designed for short, heavy draws)--that's for cranking automotive type (including marine) engines. I'd suggest marine deep-cycle batteries like [url="http://www.defender.com/product.jsp?path=-1|328|51495|306219&id=777510"]this one[/url]. WM and others probably have comparable ones.
<hr height="1" noshade id="quote"></blockquote id="quote">
I agree that starting up our little outboards should not need a starting battery. A well charged deep cycle could do the trick very well. But what about when it's nearly drained, after a long period under sail or on the hook? (VHF and stereo draw suprisingly high amperage.) Does the design of a dual purpose battery give a little extra "oomph" for starting up an outboard that a deep cycle battery would not have after being drained extensively? I realize that you could just pull the starter cord instead, but just curious anyway.

Within the last 2 months I have purchased two dual purpose batteries. Last August I was at Lake Wallenpaupack with the Trophy boat and the starting battery would not hold enough charge to start the 50hp motor, so I had to quickly pick up a new battery at Walmart. (No time to shop around.) I got a dual purpose one, since it spends 50 weeks a year powering a backup sump pump in my house. Last week I bought a second identical one, since I like to connect them in parallel on the sump pump, and the second 10-year old battery also failed a load test.

For 2 weeks a year, I pull one of these two batteries off the sump pump for the Trophy boat, and also pull one off for the C250 whenever I do multi-day cruise.

Some of the messages about internal shorts have me concerned about the way I've connected these two batteries together in parallel for the sump pump. I may need to put a fuse between them to limit the amperage in the case of a cell failure. Suggestions?

Edited by - on

OLarryR
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3370 Posts

Response Posted - 10/05/2011 : 06:03:53

I am open to what is best deep cycle vs dual purpose. But my present experience with two dual purpose West Marine Flooded (wet cell) Seawolt batteries is that they have lasted 7 years so far. I use them to start the outboard but otherwise light loads with only occasionally using them for the nav, deck and cabin lights.

Edited by - on

GaryB
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4275 Posts

Response Posted - 10/05/2011 : 06:51:34

From what I've read recently, dual purpose batteries are just what they say they are. They can be used as starting batteries and as deep cycle batteries but is a compromise of both. They will do both jobs OK but not to the full potential of dedicated starting batteries or deep cycles.

Not sure I'm going to say this correctly but I think you will get the idea. Starting batteries are designed to discharge at high amperage levels over a short time period. Deep cycle batteries are designed to discharge at low to medium amperage over a long period of time.

If you have a deep cycle it should be able to start one of our small motors but if used for that purpose on a regular basis it will probably shorten the life of the battery.

After my experience last weekend I would recommend putting fuses on both batteries along with a way to rapidly disconnect them from themselves and the load.

Edited by - GaryB on 10/05/2011 06:53:51

Stinkpotter
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Djibouti
9017 Posts

Response Posted - 10/05/2011 : 06:54:26

Starting batteries have (in relative terms) more, thinnner plates that can produce more cranking amps for a short period, while producing fewer amp-hours over a longer period. Deep-cycle batteries have thicker, harder plates that can tolerate more discharge without damage, but can't deliver as much of a punch. A dual-purpose is simply somewhere in between. The WM catalog and website has a good [url="http://www.westmarine.com/webapp/wcs/stores/servlet/WestAdvisorView?langId=-1&storeId=11151&catalogId=10001&page=Selecting-a-Marine-Storage-Battery"]explanation of the differences and rating numbers[/url]--CCA, MCA, Reserve time, and AH.

Powerboats generally have bigger engines to start, requiring a bigger burst from the battery, and are charging their batteries more of the time. Sailboats (especially 25-footers with 10hp outboards) generally don't do a lot of charging, but they do more long-term drawing from the battery (for the depth sounder, GPS, VHF, stereo, lights,...) If the sailboat has a diesel engine, it might benefit from a bank of starting batteries for that, and a bank of deep cycles for the house. IMHO, a C-25/250 should not need either a starting or dual-purpose battery to start the outboard, and should get the most "house" power per pound from one or more deep cycle batteries. Matching them gives you the most flexibility for using and/or charging them together or separately. (Unmatched, they shouldn't be used or charged together.)

Probably more important to the life of any battery is not over-discharging it, and keeping a trickle charge on it during the long periods when it isn't being used (such as over the winter for us in the north).

Edited by - Stinkpotter on 10/05/2011 07:01:24

GaryB
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4275 Posts

Response Posted - 10/05/2011 : 07:43:07

Thank you Dave! You said what I was trying to say only more eloquently!

Edited by - on

TakeFive
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2270 Posts

Response Posted - 10/05/2011 : 09:30:02

Thanks for all the info. The batteries I bought 10 years ago for my Trophy boat and sump pump were starter batteries - OK for that boat, but absolutely the wrong battery for the sump pump. Fortunately, the sump pump never had to come on during that 10 years, so it just trickled the batteries during that time.

Since the Trophy has a 50 hp outboard, I'm not sure a deep cycle battery would be a good choice to crank its starter motor. So I'm comfortable with the twin dual purpose batteries that I bought. These batteries are not generally used with the sailboat unless I'm doing a multi-day cruise (once a year, maybe), and then I pull one as a spare on the boat.

The C250 came with a WM SeaVolt flooded dual purpose battery that the PO said was only a year old. I did a load test and it passed, so no need to replace it now. But when the time comes I will consider a true deep cycle battery for it based on the info you've provided here. Although, comparing the inexpensive WalMart batteries, their dual purpose battery (24DP) which I purchased for powering the sump/Trophy starter actually has significantly higher amp-hours than their deep cycle (24DC) for only about $10 more. It's 105 Ah vs. 75 Ah at 1 amp. I'll be happy if I get 10 more years out of these batteries.

My luck was with me, because 2 weeks after getting the brand new 24DP from WalMart, Irene hit and we were without power for 12 hours while water flooded into our sump well. The backup sump pump kicked in and saved our basement. If I hadn't replaced the battery, it would have probably failed quickly and we'd have an uninsured flood mess to clean up.

Edited by - TakeFive on 10/05/2011 09:35:11

islander
Master Marine Consultant

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3994 Posts

Response Posted - 10/05/2011 : 14:45:42

The higher amp/hours can be misleading. You need to take into account how many times the battery can be recharged before its junk. What you are buying in a battery is the total amp/hours it will give you over its life. That 105 might only be able to be recharged 100 times over its life so that battery gives you 10,500 amp/hours. The 75 amp/hours battery might be able to recharge 300 times giving you 22,500 amp/hours over its life. So which one is the better value?
Amphrs x total recharges = Total amphrs / cost of the battery = Cost per amphr. The lower cost per amphr is the better value.

Edited by - on

Stinkpotter
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Djibouti
9017 Posts

Response Posted - 10/05/2011 : 15:31:01

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by islander
 The higher amp/hours can be misleading.... So which one is the better value?
Amphrs x total recharges = Total amphrs / cost of the battery = Cost per amphr. The lower cost per amphr is the better value.<hr height="1" noshade id="quote"></blockquote id="quote">...unless you're more concerned with available amp hours between charges than with how many years the battery will last. A few over-draws or over-charges could do in any battery before its expected life. Everyone's mileage varies.

BTW, 105 AH is awfully high for a Group 24 battery... I'm dubious about whether it will stand up to the slightest "abuse" that's common in a sailboat.

Edited by - Stinkpotter on 10/05/2011 15:42:19

TakeFive
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Response Posted - 10/05/2011 : 20:11:13

Good points. Don't forget that the two [url="http://www.walmart.com/ip/EverStart-24DP-4-Marine-Battery/16795211"]105 Ah dual purpose batteries[/url] are to drive a sump pump that turns on once every 10 years, and to start my powerboat a few times a day for 2 weeks a year. Both are very low drain applications, except for that one time when a hurricane comes through and I may need every bit of the 105 Ah. I'll grab one of these for an annual 3-day cruise, but only as a backup for if my C250 battery fails.

Like I said, I had two starting batteries (which were a very poor choice for this application) and they lasted 10 years - very lucky, considering the mismatch for the actual use. I have every reason to think the dual purpose could last just as long or longer.

The WM dual purpose battery is what's in my C250, and when that starts to fail load tests I will consider a deep cycle to replace it.

Edited by - TakeFive on 10/05/2011 20:13:21

britinusa
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5404 Posts

Response Posted - 10/07/2011 : 08:08:55

Thanks guys for the input.

I feel comfortable purchasing 2 deep cycle batteries, probably from WM as their return policy has been excellent.

Just add it up to this years bottomless pit

Paul

Edited by - on

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