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Catalina/Capri 25/250 Sailor's Forums

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Starter battery: Deep Cycle or Dual Purpose?

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TakeFive
Master Marine Consultant

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2273 Posts

Initially Posted - 03/28/2016 : 04:49:20

My battery failed yesterday. I had kept it at 12.8-12.9 volts all winter, but after topping off for a few hours over the weekend, voltage suddenly dropped to about 11. I brought it home, topped off the water (which wasn't terribly low), and charged overnight in my garage, but still just 11 volts. I think one of the cells has failed.

I need to think about a replacement. This battery is a dual purpose battery that I had originally bought as a starter battery for my 50 hp motorboat. Shortly after buying it I re-purposed it for Take Five. So I am confronted with the decision whether to buy another dual purpose, or go with a deep cycle battery instead.

I've read multiple places (and repeated here) that the starter motors for 8-10 hp outboards can run off of deep cycle because they don't draw that many cranking amps, but I've never personally tested this hypothesis.

What experience do all of you have with deep cycle batteries doubling as starter batteries for these small outboards?

Rick S., Rock Hall, MD
PO of Take Five, 1998 Catalina 250WK #348 (sold in 2016)
New owner of 2001 Catalina 34MkII #1535 Breakin' Away (sailing from Swan Creek in Rock Hall, MD)

Edited by - TakeFive on 03/28/2016 05:32:21

dasreboot
Admiral

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804 Posts

Response Posted - 03/28/2016 : 04:59:51

deep cycle works fine to start my 9.9 honda.

Todd Lewis
Eowyn 87 TR/WK C25 #5656
ARWEN 84 TR/SK C25 #4031
www.mainsailsailingschool.com

Steve Milby
Past Commodore

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5932 Posts

Response Posted - 03/28/2016 : 05:16:41

On the recommendation of my marine service man, I use deep discharge batteries for both the house bank and starter battery for my 30 hp Yanmar diesel engine. I would probably use a dual purpose starter battery if my engine was a big, marinized automotive V-8, but for these smaller motors, I think a deep discharge battery works well and withstands deep discharge better.

Steve Milby J/24 "Captiva Wind"
previously C&C 35, Cal 25, C25 TR/FK, C22
Past Commodore

TakeFive
Master Marine Consultant

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2273 Posts

Response Posted - 03/28/2016 : 05:37:11

OK, thanks for the advice so far. This is good news, because it means I can pull the new battery off of Take Five for the one week each year that I use my 50 hp outboard.

I guess my question is complicated somewhat by the rumors that I have heard that many battery retailers (Walmart, Interstate?) have started labeling their dual purpose batteries as deep cycle. So my follow-up question would be how to tell whether someone is selling me a true deep cycle battery, as opposed to a dual purpose one that's just labeled as deep cycle?

Rick S., Rock Hall, MD
PO of Take Five, 1998 Catalina 250WK #348 (sold in 2016)
New owner of 2001 Catalina 34MkII #1535 Breakin' Away (sailing from Swan Creek in Rock Hall, MD)

Edited by - TakeFive on 03/28/2016 05:39:19

Davy J
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Response Posted - 03/28/2016 : 06:11:33

Check the label for Ah (amp hours). Deep Cycle group 24 should be around 75Ah, dual purpose might be somewhere around 65Ah.

Davy J

2005 Gemini 105Mc
PO 1987 C25 #5509 SR/SK
Tampa Bay

TakeFive
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2273 Posts

Response Posted - 03/28/2016 : 06:41:26

quote:
Originally posted by Davy J

Check the label for Ah (amp hours). Deep Cycle group 24 should be around 75Ah, dual purpose might be somewhere around 65Ah.

I will check that, although even that can be misleading. Walmart used to quote Ah at 1 amp, which inflated their ratings because at the lower drain rate the voltage stayed above 11.8 for longer. They rated my Group 24 dual purpose battery at 105Ah, which was just ridiculously exaggerated.

Rick S., Rock Hall, MD
PO of Take Five, 1998 Catalina 250WK #348 (sold in 2016)
New owner of 2001 Catalina 34MkII #1535 Breakin' Away (sailing from Swan Creek in Rock Hall, MD)

Steve Milby
Past Commodore

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5932 Posts

Response Posted - 03/28/2016 : 06:55:43

I found this webpage online that deals with the subject. http://www.pbase.com/mainecruising/deep_cycle_battery

The author says: "There are only two companies I know of producing 4D or 8D deep cycle batteries Dyno and Rolls."

I found a price online for a Rolls group 27 12v. deep cycle battery of $1055. I couldn't find a price for a similar Dyno battery, but suspect it would be similar. I'm not paying $1000. + for a battery; I don't care how good it is.

If I really wanted a superior system, I'd use golf cart batteries, which are recommended by lots of liveaboard cruisers, but that would require installing different battery boxes and mounts, and IMO, it's not worth the trouble. I use my batteries hard to run my refrigeration. Interstate 12v. deep cycle batteries meet my needs and last about 3 years or more, and cost about $100. each.

Unless you're running refrigeration and cruising and off the grid for long periods of time without solar recharging, I would think two 12v group 24 or 27 batteries would provide more than enough power.

I have the impression that the author is talking about the best system, without regard to cost. That's not the real world. I don't need $2100. worth of batteries. I need $200. batteries, and will happily replace the ones that are generally defined by battery manufacturers as deep cycle batteries every 3-4 years.

Edit: I just found this discussion on sailnet. Mainesail discusses the subject of using a deep cycle battery for starting a small sailboat engine. See especially post # 12. http://www.sailnet.com/forums/pacific-seacraft/246625-dedicated-starter-battery-all-deep-cycle-2.html

Steve Milby J/24 "Captiva Wind"
previously C&C 35, Cal 25, C25 TR/FK, C22
Past Commodore

Edited by - Steve Milby on 03/28/2016 07:12:16

Davy J
Master Marine Consultant

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1511 Posts

Response Posted - 03/28/2016 : 07:24:09

I think I would avoid Walmart. Looked at the batteries online. They list the group 24 deep cycle but don't list Ah. They listed capacity as 65, whatever that means. I also checked Sam's club, where I last bought batteries, and they list the Ah for group 24 as 75.

Davy J

2005 Gemini 105Mc
PO 1987 C25 #5509 SR/SK
Tampa Bay

Steve Milby
Past Commodore

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5932 Posts

Response Posted - 03/28/2016 : 07:31:27

I just found this discussion by Mainesail of the question of mislabeling of deep cycle batteries. http://www.sailnet.com/forums/3175322-post1.html

His advice is: "When buying batteries please try to stick with a brand name unless you know EXACTLY what the product really is under the resellers sticker."

"Trojan, Deka/East Penn, US Battery, Dyno, Interstate, Exide, Crown, Lifeline, Full River, Firefly, Odyssey, Northstar etc. are all BATTERY MANUFACTURERS."

"Sticker brands such as Kirkland, Power Star, All Rounder, Energy Master, Auto Craft, Powertron, Super Start, Maxx Marine, Cabella's, Duralast, Sportsman etc. etc. are all STICKER BRANDS and you have little to know idea what you are really getting unless you do some extensive leg work. Even then many sticker brands hide who the actual manufacturer is."

Steve Milby J/24 "Captiva Wind"
previously C&C 35, Cal 25, C25 TR/FK, C22
Past Commodore

islander
Master Marine Consultant

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4038 Posts

Response Posted - 03/28/2016 : 09:52:39

You can also check the weight of the battery. A cheap deep cycle battery will have thinner lead plates to cut the cost down verses a well made deep cycle with thicker lead plates. The well made battery will weigh more than the cheap one. A deep cycle battery will have no problems starting our motors. Think about how big a motorcycle battery is and they have no trouble starting engines that are higher horsepower with higher compression than whats on our boats.

Scott-"IMPULSE"87'C25/SR/WK/Din.#5688
Sailing out of Glen Cove,L.I Sound

Dave5041
Former Mainsheet Editor

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3758 Posts

Response Posted - 04/02/2016 : 12:57:39

Just did some research since I dropped one of my Deka batteries off loading it with Pearl on the trailer and cracked the case (only 1 year old

). Anyway, Deka's aren't available locally and I was hoping to get it replaced before taking Pearl to Lake Erie. Costco, Duracell, and NAPA premium deep cycle batteries are built by Deka, EastPenn, to the same specs as Deka branded batteries. The specs on group 27's are all the same, and they all way 53 pounds and half the price of WM.

Dave B. aboard Pearl
1982 TR/SK/Trad. #3399
Lake Erie/Florida Panhandle

Edited by - Dave5041 on 04/02/2016 12:58:45

islander
Master Marine Consultant

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Response Posted - 04/03/2016 : 06:11:40

I'm a big fan of Deka batteries. we used them in all of the heavy equipment and trucks at work. They would hold up to the pounding and vibration that construction equipment can put out. Other brands would fail in a year or less. I have them in my car and boat. I usually get 7+ years put of them.

Scott-"IMPULSE"87'C25/SR/WK/Din.#5688
Sailing out of Glen Cove,L.I Sound

Voyager
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Response Posted - 04/03/2016 : 08:57:04

Scott, we all know you get what you pay for. Are Deka batteries significantly more expensive than an Interstate or other brand name?

Bruce Ross
Passage ~ SR-FK ~ C25 #5032

Port Captain � Milford, CT

islander
Master Marine Consultant

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Response Posted - 04/03/2016 : 10:19:43

Probably competitive with other quality battery's. The hard part is finding on outlet or dealer that has them. WM batteries are Deka rebranded. I was able to get them at cost through work and there is an outlet here on L.I. There is a lot of rebranding in batteries but you can usually find out the maker of a rebranded battery by compairing model or serial #. By the way Bruce, I've heard good things about the Sportsman batteries that Defender sells and with their early spring sale a new battery could be a score. I think (not sure) they are made by Mid State Batteries, A Conn. company in Bloomfield.

Scott-"IMPULSE"87'C25/SR/WK/Din.#5688
Sailing out of Glen Cove,L.I Sound

Edited by - islander on 04/03/2016 11:57:22

Dave5041
Former Mainsheet Editor

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Response Posted - 04/03/2016 : 14:07:09

Just be careful with rebranded, just because a quality company makes them doesn't necessarily they are always equal to the manufacturers brand. Compare specs and the standard used for the specs. I used to buy Walmart batteries, but they changed source and get their amp hour rating using the 1 amp draw standard, not especially useful. Compare weights in addition to the other specs. If they go to the expense of dense lead plates, the other components are probably good. MTD, for example, builds lawn/garden tractors and mowers for John Deere, Cub, Ariens, Sears and many others, including some very inexpensive house brands. They are not all built to the same specs.

Dave B. aboard Pearl
1982 TR/SK/Trad. #3399
Lake Erie/Florida Panhandle

Edited by - Dave5041 on 04/03/2016 14:10:29

islander
Master Marine Consultant

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Response Posted - 04/03/2016 : 14:33:35

That's exactly the reason I said to compare serial #s. For instance a WM group 27 has the same serial# as the Deka group 27. If they were different #s then it might be a lesser quality battery made to meet a price point for the retailer they are supplying.

Scott-"IMPULSE"87'C25/SR/WK/Din.#5688
Sailing out of Glen Cove,L.I Sound

Stinkpotter
Master Marine Consultant

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Djibouti
9089 Posts

Response Posted - 04/03/2016 : 20:08:53

quote:
Originally posted by islander

...By the way Bruce, I've heard good things about the Sportsman batteries that Defender sells and with their early spring sale a new battery could be a score. I think (not sure) they are made by Mid State Batteries, A Conn. company in Bloomfield.

They've worked and lasted very well for me. But Defender's big annual warehouse sale ended today.

Dave Bristle
PO of 1985 C-25 SR/FK #5032 Passage before going over to the Dark Side (2007-2025); now departed from Mystic, CT, and boatless for the first time since 1970.

Edited by - Stinkpotter on 04/03/2016 20:10:09

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