Battery Question

L

Lyle

New member
Hello,
I recently bought a 1983 22 foot C-Dory at an estate sale.
The boat has no batteries but takes two.
I don't know what type of batteries to buy or if they should both be the same or one a deep cycle.
It has some kind of dial type switch by where the batteries go.
The motor is a 115 HP Evinrude.
Any info will be greatly appreciated and I thank you.
Lyle
 
Hey Lyle, Im in a similar situation. I just purchased a 2006 23 foot cape cruiser in the fall and in getting it ready for halibut fishing found one of my batteries to be done... It came setup with a deep cycle battery for a house battery and some kind of cranking battery to be used as a starting battery. I have a 115 yammy as a main also and too am curious what other guys are using? 2 deep cycle batteries? Or do most guys running a single main go with a starting and house battery type setup?

I would like to eventually get to, 2 6 volt batteries wired in series for my house setup... but dont want to be buying 3 batteries all at once...

Yak
 
Well, other may disagree with me, but here's my position:

The 115 Yammy or 115 Evinrude outboard motors don't require the hundreds of amps that a cold automobile V-8 needs to start.

A good deep-cycle marine battery can easily start an outboard like this, so why go with a starting type battery with thinner plates and one that is therefore prone to be damaged by accidental deep discharge, and generally has a shorter service life?

Get two deep cycle batteries with their heavier plates that can stand more abuse, deeper discharges, and will have a longer life expectancy.

I believe this and practice this, even to the degree that I have four group 27 deep cycle batteries on my CD-22 that can be connected in any configuration possible, including one big combined parallel 4 battery unit.

Never found the bottom of the 460 amp-hour system yet or failed to start the engine on demand.

That's my story and I'm stickin' to it!

Joe. :teeth :thup
 
I would just go with deep cycle batteries. I agree with Joe. C-Cakes came with three GP24 Optima Blue Top batteries. They lasted about 3 1/2 years. I replaced the house and one start with the same thing but found that Optima had been sold and the new batteries were not, in my opinion, as good. One failed within a few months, the other soon after. I decided to move away from Optima but there was lots of debate about AGM versus other types. I ended up going with regular deep cycle (non-agm) GP24s for both house batteries and, at Les's suggestion, AGM motorcycle batteries to start my little 40hp engines. This setup has worked well for our type of cruising. To me the house batteries are where you should put the most amp hours, that is what you will use for your heat, lights, windlass, etc. The battery to start your engine is used just for that purpose and doesn't need the same capacity. So, in your case i would probably go with a GP24 deep cycle for the start and a GP27 deep cycle for the house.
 
I have 2 Optima Blue Top deep cycle batteries that I interchange for my Minnkota Trolling motor on my Gheenoe Custom LT 25. They go back to 2007 and are still taking a charge very well. Optimas are pricey but seem to be very reliable and you never need to add distilled water to them.
 
I'm with Joe. Measure your battery holder or box if you can fit them I would (did) get a couple deep cycle group 27 batteries. If you want to go more towards the high end we are trying some group 27 Cabela AGM batteries that don't require adding distilled water. They were recommended by others in this forum. So far so good.
D.D.
 
I've heard numerous complaints about Optima batteries after the change of ownership.
Do your homework and decide for your self.
 
Not to knock Optima, but I fail to see the advantage of AGM or Gel Cell batteries in a boat like the C-Dory, unless you're using them in a tightly enclosed cabin or plan on being upside down a lot.

Security for me, at least, is in having plenty of amp-hours in reserve, so that the electron bank won't go broke.

The advanced types of batteries are great if you have an airplane, a racing hydroplane, a dragster, or some other high performance option that requires zero gas emission, upside down operation, vibration toleration, and/or zero maintenance.

However, they're at least two, usually three times as expensive as the equivalent wet cell batteries, and usually have smaller capacity in terms of amp-hours for their size.

I'll bet a lot of folks who buy the more expensive types are doing so out of a felt need for more "battery security", and therefore buy the more expensive types, while much more security could be bought by just buying two or three regular wet cells for the same price. (?)

C-Dory Cruiser 22 #286, Electric Boat Division, General Dynamics, Groton, Ct, USA

Joe. :teeth :thup
 
I've tried quite a variety of batteries, the ordinary flooded ones that came with my C-Dory, 6V flooded deep cycles, West Marine (Deka) gels, Optima spiral-wound AGM's, Deka dual-purpose AGM's, and Deka's more cranking-amps-oriented AGM's. For me, the AGM's are far superior.

No maintenance, no spillage or corrosion

Can be discharged deeper without damage

Very much slower rate of self-discharge when sitting unused

Less likely to be damaged by freezing temps over the winter

and they LAST, enough to offset much of the pain of their higher price.

The Optimas in my diesel truck would still crank the Cummins after sitting 3 months in the parking lot while I was out cruising, even when they were more than 9 years old. They finally got to where they cranked too slowly in their tenth winter outside, sitting unused much of the time.

Deka dual-purpose G31 AGM's, 105AH-each (the boat's house bank) lasted 11 years, and hundreds of nights at anchor without a generator, before I replaced them with another pair. The boat's Optima starting batts lasted 7 years.

They just flat work better. For me, they're well worth the cost.
 
First of all, I'm no expert, but... within that... I think a lot depends on how you plan to use the boat, and how you plan to keep the boat when you are not using it.

Examples of what I'm thinking:

Two use cases that would put very different loads on the house bank:

1) Run out fishing for a day, motor(s) are on much of the time, run back.

2) Motor for a few hours to an anchorage and then spend two days living on the hook.

Storage:

1) Kept on a trailer at home, with a shore power "hookup" right there.

2) Kept on a mooring, with no "plug in" available.

You can probably see how the above "extreme" situations would call for different set-ups. Use scenario one puts very little strain on the house battery(s), and in addition the engines are charging them pretty much constantly. Scenario two will put much more of a strain on the house bank, as you motor very little (thus charge very little) and then try to "live" on the house bank over a period of days.

Storage scenario one is also different from scenario two.

From what I have learned the "simple, basic" setup (and that's not to say it's a bad or even lesser choice at all) is two identical deep cycle batteries, often Group 24, with a switch between them, and you just pick one for starting and one for house and then you can alternate days if you want to. You may have a bit "less" battery than you could have for house, and a bit more than you need for start, but it's perfectly adequate in many situations, and simple.

A more "cruising boat" setup may be to have a dedicated start battery (which can be smaller but still needs to be adequate) and then a larger, dedicated house battery. This would be lend itself more to a scenario two type of setup.

You can add a VSR (such as Blue Sea ACR or other brand).

One thing to keep in mind is how many amps your engine puts out (alternator), how long you plan to motor as opposed to using juice, and what other (if any) sources you have to "put back" amp hours (shore power, generator, solar panel, etc.) It's good to keep a balance. For example, if you are relying solely on the engine alternator to charge the batteries, you don't want to have a huge bank (many amp hours), run it way down, and then have to motor 27 hours to bring it back up.

Another consideration when planning amp hour usage is that you don't want to run batteries down below 50% charge if you can help it - it kills them much faster. So if you have an 80 amp hour battery, that's really 40 (or so) you want to use.

My boat came with the typical setup (two group 24 batteries and a manual "Off-1-2-Both" switch. I'm sure it would have worked fine, but since the batteries were old and dead, and since I hope to have cruising scenario two, I went with a smaller, dedicated start battery, and a deep cycle Group 31 house battery (only very slightly physically larger than a Group 27, but more amp hours). I put in a VSR and an "On/Off (combine)" switch. I don't have a charger (yet), but may add one.

I went with AGM batteries, because the way my house battery is situated it would have been hard to check/fill water level on a flooded cell battery. As it turns out, I also mounted the start battery on its side, for more efficient space usage (you can do that with AGM's).

Upshot seems to be that many systems will work, and some may be slightly better for various specific use-case scenarios.

Sunbeam
 
I'm no expert either but we use our boat a fair amount and in different ways. Sometimes just fishing for a weekend sometimes we are on it for a month at a time. I'm not sure why I would be using a smaller battery for starting and using a group 31 for the house. It just seems that you are missing out on a chance for more amp hours. I could see a couple group 31's if you can get them too fit. When we anchor out for a night, I leave our battery switch on the one battery we have been using all day. I have always been able to start the engine without having to throw the switch to the other battery the next morning. Getting stuck somewhere with weather is not a problem as we carry a generator on those kind of trips that we use with a shore power cord and through our Shore power and an on board charger so I don't think we would ever be left flat with no juice. We normally don't anchor out for more than a day at a time as my better half likes the idea of a shower and a regular basis. Our boats that used two batteries where always equipped with the same sized batteries. Maybe just a habit. Fishing boats have trolling motors and live bait well and keep electronics going at all times even when the main engine is off. So I wonder why a group 31 house and a smaller start battery. Is that a money thing,weight? I don't see an advantage of using a smaller start battery over lets say two group 27's or two group 31's if you can fit them. I'm mean whatever works for you is fine with me. Just wondering.
D.D.
 
It's a weight thing, or maybe weight and space. Having the start batt(s) take less space and weight allows for a larger house bank.

A larger house bank, rather than two alternate house banks, can provide more amp-hours at anchor without damage to the batteries. The larger house bank can last longer.

Or, another way to look at it is you can save fuel by dragging less total weight around.
 
And a Deka g34 cranking-oriented AGM weighs only 41.5 lb, yet it provides 775 CCA. Similar to an Optima g34 in size and weight. My truck needs two, and so does the diesel boat. A pair of these weighs only a little more than a g31, and offers far more CCA.
 
My reasoning is along the lines that New Moon explained. Also, it's what I'm familiar with. In a slightly larger cruising boat, we had one single Group 24 start battery. This could be a rather ordinary, easily replaceable battery. It started the engine easily (and actually never had to be replaced). For the house bank we had nearly 400 ah of AGM batteries. There's no way we could have fit two of those banks, nor afforded them. Now, the C-Dory is on a different scale, which is why I said that - from what I can tell - either the "runabout" or the "cruising" system will work fine. I'm just explaining where I am coming from since you wondered.

You asked about weight: For starting, I have a small AGM starting-type battery with 560 CCA. It weighs 33# and is about 6" x 7" x 8". My house "bank" is one Group 31 deep-cycle AGM battery. It has 115 ah, is just slightly larger than a Group 27, and weighs 72#. For myself, I didn't want to purchase, fit (space-wise), or carry a second Group 31 just for starting (i.e. to go with the two-matching-battery type system). Right now I have 105# of batteries, and a 115 ah house bank.

If I did have a second Group 31 I would make it part of the house bank, and still have the smaller starting battery for starting. However, right now I don't have the means to re-charge such a large house bank, nor do I know if I need it. I would also have a problem fitting two Group 31 batteries into the lazarette (certainly not also with the starting battery), so I don't want to "go there" unless and until I need/want to.

I have a battery monitor that monitors one bank - it's hooked up to the house bank (although one can also monitor two banks if they have a second house bank; but it would require a different monitor).

It seems that both systems can work well. It also seems that the "runabout" style (which my boat came with) is simpler and cheaper (two Group 24 flooded batteries and the traditional "Off -1-2-Both" switch). I simply wanted the style of system I put in for my uses (and the batteries the boat came with were ten years old and ready to be replaced, so it seemed like a good time).

Sunbeam
 
For my 22 Cruiser with twin 40's I have 2 group 29 deep cycle batteries. One in each lazarette, shoehorned there by my boat mechanics. There is an Off-1-2-Both switch which is generally run in the both position, for running and for over night. Over night use is generally running a CPAP machine and some 12VDC chargers, (phone, handheld VHF etc). I check the battery levels independently and on both, morning and evening. The Batteries are Interstate, Deep cycle and are on their 5th year with very little degradation in charge holding capacity. (Typical after a day running in 12.7 or 8 Volts and after a night of 7 hours 12.4-5 is usual). They have never failed, and I will probably replace next year on general principles rather than wait for a "have to do it now" situation.

Harvey
SleepyC:moon
 
Thank you to everyone who replied to my post/question concerning what battery to get for my C-Dory.
I ended up with two G 31 batteries and I believe they will be sufficient to do everything I need.
Thanks again for all the great info you posted!
Lyle
 
I missed this discussion the first time around, but I'm sure interested now.

One of my Optima blue-tops won't take a charge! And boo-hoo-hoo, it's only 9 years old! :) Sounds like I've gotten good life out of these batteries, from what folks have said above. The other one's still going, so I guess I'll keep using it for the moment.

In the meantime...what should I get to replace this bad one now? So many opinions expressed above...it's hard to choose.
 
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