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Dave S
09-18-2007, 06:22 AM
One of our other members on the board was conversing with me via email asking about my battery set up. It turns out that both his 260DA and mine were delivered with two 27AMP Cranking Batteries.

When it comes time to replace these batteries, I was wondering what to do. I guess I am disappointed that Sea Ray didn't see fit to install at least one Deep Cycle battery for use as the "house" battery. Would that be the way to go in the future.........one Starting and one Deep Cycle? Or would two Deep Cycles be better? Or maybe I should leave well enough alone and just replace with cranking batteries? :smt017

lorenbennett
09-18-2007, 07:38 AM
I use the walmart brand of deep cycle/ starting marine combo. IT extremely hot and two years is all that we will get out of them anyhow. :thumbsup:

gyrospiro
09-18-2007, 06:45 PM
On my boat there were 2 banks of 2 cranking batteries, the port would drain completely in 3 hours with just frig and stereo on. I replaced the port cranking batts with deep cycles now i can last overnight with out any problems(the port batteries run port engine and act as house batts).

Sorrento 25
09-18-2007, 08:16 PM
One small starting, one huge deep cycle, and the Blue Sea add-a-battery setup with the Dual Circuit switch and ACR ($120).

Dave S
09-18-2007, 11:09 PM
Are there any issues with my onboard battery charger if I mix starting and deep cycle batteries?

Sorrento 25
09-19-2007, 09:32 AM
There shouldn't be as long as they are the same type. The higher capacity battery will just take more charge.

estebanj
09-20-2007, 09:28 AM
Dave... I'm thinking the same... when it comes time to replace, I'll get one cranking and one deep cycle. This is how I had it on a previous boat.

Esteban

LtCdr. Augs
09-20-2007, 09:52 AM
Have you all considered the Optima Yellow top's? It's a combined, sealed, deep cycle and starting battery. I replaced all the deep cycles on my RV with them, both the Coach batteries and the engine start batteries.

Problem is they are spendy. Good news is they are rugged, take a beating and because of their design, can be mounted in any position. They also market a true marine dual battery design I believe. I'm just not personally knowledgeable about them.

I gotta believe there are Optima installtions out there somewhere in Sea Ray's.

I'll put them on my 260 as soon as I take ownership this weekend.

Here's a link:

http://www.1st-optima-batteries.com/

Augs

Sorrento 25
09-20-2007, 10:46 AM
Optimas are great cranking batteries but do not have much capacity as a house deep cycle. I have one for a cranking battery.

Nehalennia
09-20-2007, 11:14 AM
Dave,
As you know I don't intend on installing a geni in whatever boat we end up with. What I do want to do is install an inverter or inverter/charger which will provide us the power we'll need when on the hook.
I think the 2 -27AMP Cranking Batteries are good to have for the normal operation on the "engine" side. This way you can add an isolator, so while underway you can charge the two starting batts and whatever house batteries I decide to go with(thinking AGM now). When on shore power (since I don't know exactly the capabilities of the Stock charger) I hope will be able to charge all 4 batteries. I'm not sure if I need a separate isolator for the charger and one for the alternator side.

Sorrento 25
09-20-2007, 11:20 AM
Here is what I did with two Trojan L16HCs for the inverter, two group 27 house batteries, and two Optima Blue Tops for cranking:

http://webpages.charter.net/Altimat/Sorrento/Schematic.jpg

On alternator or shore power (Pro-Sine 2.0 Inverter/Charger) all banks charge automatically independent of the switch. The ACR distributes the charge to either the house or inverter banks as needed, and the Duo-Charge sips some charge for the start battery as needed. The Dual-Circuit switch is either on or off, and the start battery is completely isolated and cannot be drained down. The 24 hour bilge pump is on the house bank.

Sundancer
09-20-2007, 11:21 AM
Whats the cost and expected life of an AGM Battery? Does it warrant the extra cost? I keep hearing that properly maintained regular lead batteries are cheaper in the long run? I usually get at least 3 years out of mine and have gone 4 years on occasion?

Dave S
09-20-2007, 12:17 PM
Here's another link on batteries that contains a lot of really good information. http://www.marine-electronics.net/techarticle/battery_faq/b_faq.htm#4

Dave M.
09-20-2007, 12:18 PM
Frank Webster is very happy with his AGM batteries. I think he mentioned in another thread he had switched to them 7 years ago, and would never go back. Maybe he can tell us if he is still on the first set.

In my boat, the #1 start battery is really 2 batteries in parallel. They are Stowaway ST27DP deep cycle (http://www.exide.com/products/marine_rv/stowaway_marine_deep_cycle.html)batteries. It appears the part number has changed since mine were made. Mine are listed as 700 marine cranking amps, 575 CCA, and 160 Reserve Capacity. Mine were made in Sept 2002, so they are 5 years old now. So far I have seen no sign of a need to replace them.

I don't see why anyone would ever use a battery that was a normal start battery in a boat. A deep cycle battery like the Stowaway should start the engine just fine, and not be broken if you cycle it. An auto battery needs to be able to start your engine when the temp is -20 F. At that temperature the battery capacity is severely reduced. But you normally don't do that with a boat. I would expect that the battery surroundings temp would be at least 32 F, or you would be in freezing water. And even at that, for that cold temp, you can use the BOTH position to start the engine in that unusual circumstance. Seems to me like a deep cycle, pair of golf cart batts, or AGM is the ticket.

Dave S
09-20-2007, 12:24 PM
Dave........Sea Ray installed cranking batteries in my 260DA. They are Interstate 24 M batteries shown here on their web site http://www.interstatebatteries.com/www_2001/content/products/product_marine.asp

LtCdr. Augs
09-20-2007, 01:44 PM
Sorento 25

You said:

"Optimas are great cranking batteries but do not have much capacity as a house deep cycle. I have one for a cranking battery."

The Optima D31M is a larger body marine battery with 900 CCA and 1125 CA.

I use two of the yellow top versions for my Motorcoach in deep cycle mode and two more for starts and have for years. What marine requirement are you thinking of that makes you say they don't have much capacity as a deep cycle battery. Am I missing something?

Very nice schematic by the way...

Dave M.
09-20-2007, 03:10 PM
Dave........Sea Ray installed cranking batteries in my 260DA. They are Interstate 24 M batteries shown here on their web site http://www.interstatebatteries.com/www_2001/content/products/product_marine.asp

Dave, the link is very nice. I think it gives you information you need to choose a replacement battery if you stay with Interstate. You see that the starting batteries do not list any specs for 5A, 15A and 25A load. They are not designed for that. But in a boat, you are normally going to have current draw for the Mercathode if in the water, and a bit of draw for the radio memory. Not much, but it adds up over time if not being charged.

It seems logical to me to replace the group 24 starting battery with a group 27 deep cycle, such as the SRM-27B. With the latter, it tells you how much load it will support for how long. Then you just need to calculate if that is enough for your intended use. With that battery, they don't give an amp-hr capacity rating, suggesting it is not really intended for use to carry load over time. But if you take the 5 amp rating of 20.4 hrs, you can see it is about a 100 amp-hr battery. The cranking amps rating tell you it is designed to push enough current to turn a starter.

As you go down the page, you can see how they change what is specified, and that tells you what they designed the battery to do. The 12 volt golf cart battery is specified for amp hrs, and not cranking amps. So it may or may not be able to turn your starter, they don't claim it can. It is heavy at 90 lb, and is a 155 amp-hr battery designed to be cycled at 25 to 75 amps (that's where they specify it).

Then at the bottom of the page is a GC-2. GC implies golf cart, and you see it is specified at the same 25A and 75A as the 12V battery. But now, it takes two batteries to get 12V ( to keep weight down), and has an increased rating of 225 amp hrs. Using the RC (reserve capacity) rating at 75 amps, it would power an inverter at 75 amps for 122 minutes, or two hours. That would give you about 2 hours of 120 VAC at around 800 watts. Or one hour of a 1500 watt hair blower. But the 75A rating suggests that is towards the upper end of its design curve, it is meant to put out 75A at 12 volts, or 900 watts. So if you wanted to run a 2000 or 2500 watt inverter, and load up the inverter, you might want two pair of these in parallel, giving a spec point at 1800 watts.

There is no magic. In batteries, it is just a matter of finding a battery that matches your need. When you find a good site like the Interstate one you have posted, that gives you specs for the different battery types so that you can compare them, then you have gone a long ways towards being able to make a reasonable choice.

I will say that right now, in my boat, by #2 battery on the Guest switch is a single pair of GC3 batteries, very similar to the GC2. The other half of my house battery set (the other two GC2 batteries) are currently in my fifth wheel trailer. At 70 F I can tell no difference in starting my engine using the pair of Gp 27 batteries on Guest Switch Position 1 or the GC batteries on Position 2. If the temperature were 20 F, and the engine were that cold too, and I had single weight engine oil, it might be a very different story.

Dave S
09-20-2007, 03:52 PM
Dave.................or to put in another way the higher the RC (Reserve Capacity) the longer the battery will work without being recharged.......right?:smt017

In our case for overnighting our 12v draw will be house lights, refrigerator, water pump, TV, radio, etc. So I am not sure what the total draw is at any given time nor how long it would be sustained.

Dave M.
09-20-2007, 10:27 PM
Dave.................or to put in another way the higher the RC (Reserve Capacity) the longer the battery will work without being recharged.......right?:smt017

Yes, that is correct. It is the number of minutes that the battery will supply the current specified. If no current is specified, then it is generally accepted to be 25 amps.


In our case for overnighting our 12v draw will be house lights, refrigerator, water pump, TV, radio, etc. So I am not sure what the total draw is at any given time nor how long it would be sustained.
So, you need to learn through experience, make some educated guesses, or have someone on the board that knows tell us. If you are trying to decide in advance, then learning through experience isn't the best choice, unless it is someone else's.

I would suggest that you make a spreadsheet and put in some numbers.

I know that my refrigerator draws about 3 amps when it is on. I think it runs less than half the time, maybe 1/4 of the time. So I could claim it draws about an amp on average. So in a 24 hour period, it would draw 24 amp-hrs.

Maybe in a 24 hour period, your house lights are on for 4 hours. I just measured mine, and with them all on, the current draw for the lights was about 6 amps. Power used is volts times current, so thats 6A times 12V, or 72 watts. About the same as a single 75 watt light bulb, reasonable for my 270 with its dim lighting. So the amp-hr use, if used 4 hours, would be 6A times 4hrs, or 24 amp-hrs.

The water pump only draws current when it is running, which I think is not more than a few minutes a day. Mine draws 4.5 amps when running, and pumps about 2.5 GPM. So it would pump 15 gallons (3/4 of my 20 gal. tank) in 6 minutes (1/10th hr), So to pump 3/4 of my fresh water tank, it would draw 4.5 amps for 0.1 hr, or 0.45 amp-hr. Ignore it!

Let's say the radio is on for 4 hours, and the TV is on for 4 hours. If the radio draws 25 watts on average, and the TV draws 50 watts on average, that is about 2 amps for the radio and 4 amps for the TV. These are total guesses on my part. If so, the radio would draw 2A*4hrs or 8 amp-hrs. The TV would draw 4A*4hrs or 16 amp-hours.

So the total estimate here is refrigerator, 24 amp-hrs, lighting 24 amp-hrs, radio 8 amp-hrs, and TV 16 amp-hrs, for a total of 72 amp-hrs.

The highest load, ignoring the water pump, is when the TV, cabin lights, and refrigerator are all on. That is a draw of 4A (TV) + 6A (lights) + 3A (refrigerator), or 13 amps max (remember just estimating here). But 13 amps is just half of the 25 amp load used for reserve capacity calculations, and you get more amp-hrs out of a battery when the load is less. So if we use reserve capacity to estimate battery amp-hr rating when it is not given, we should get a conservative number.

The SRM-27B battery has a reserve capacity of 3 hours at 25 amps, which is 75 amp-hrs. So the 72 amp-hrs withdrawn over 24 hours as above will almost completely discharge it, and it is a group 27 battery. If it were a group 24 starting battery, it would be destroyed in short order. The SRM-27B will survive a bit longer. It might stand 300 cycles (how may weeks or years is that?) if we could totally charge it up between discharges. For that, you have to have it on a good charger running on AC for maybe 2 days minimum. Use a pair of the SRM-27B batteries, and now you are talking reasonable numbers.

If you go to the bottom of the Interstate battery page (http://www.interstatebatteries.com/www_2001/content/products/product_marine.asp) you linked to, and look at the GC2 batteries, they are 6V and about 230 amp-hr capacity. Two in series gets you a 12V battery plant with 230 amp-hr capacity. The load estimated above is about 1/3 of its capacity. It might go 1000 cycles or more, which is maybe 500 weekends, 10 years almost every week. This battery set will die from age, or lack of maintenance, before it dies from cycling and providing power.

Those are my guesses, and I would invite comments on what better info people may have get make it a better guess.

RjVA
09-21-2007, 07:29 AM
I would not want to rely on one cranking battery. I'll "abuse" my battery's while at anchor by draining them more than they like, but, will always have at least one cranker to start. What if you primary cranking battery decided to fail? Would you feel ok using a deep cycle to start you engine? The optimal setup in my opinion for a single engine is 2 crankers and one deep cycle for the house, but personally, just working both crankers equally, not letting them get too drained and replaceing them at the first sign of problems is key. Now that I have a boat with a charger, it makes life easy. On my ski boat, I have a dual setup no charger. The batteries get pounded hitting wakes for wakeboarding etc (this is by far the worst thing that can happen to batteries). I run an amp for my tower speakers ALL day during anchor outs. I am anal to say the least about working them equally. I do how ever let them get over drained. Because of these factories, that last 1 boating season.

boatdoc100
09-21-2007, 07:36 AM
One of our other members on the board was conversing with me via email asking about my battery set up. It turns out that both his 260DA and mine were delivered with two 27AMP Cranking Batteries.

When it comes time to replace these batteries, I was wondering what to do. I guess I am disappointed that Sea Ray didn't see fit to install at least one Deep Cycle battery for use as the "house" battery. Would that be the way to go in the future.........one Starting and one Deep Cycle? Or would two Deep Cycles be better? Or maybe I should leave well enough alone and just replace with cranking batteries? :smt017

You should always use deep cycle batteries. The best out there is the Delco Voyager, they cost a little more but my customers regularly get 5 to 6 years out of them.
Brad

boatdoc100
09-21-2007, 07:38 AM
Are there any issues with my onboard battery charger if I mix starting and deep cycle batteries?

There will be no problem doing that Dave.
Brad

boatdoc100
09-21-2007, 07:41 AM
Whats the cost and expected life of an AGM Battery? Does it warrant the extra cost? I keep hearing that properly maintained regular lead batteries are cheaper in the long run? I usually get at least 3 years out of mine and have gone 4 years on occasion?

I go through hundreds of batteries a year and find that regular lead acid is most cost effective and a better way to go. They need to be maintained which forces a boater to remove and clean electrical terminals annually. The gels and others get put in and forgotten. Two years latter they are calling me for a service call simply because of dirty terminalls and they boat wont start.
Brad

MLauman
09-21-2007, 08:01 AM
If you're not gonna do AGM, take a look at Interstate's SRM-29. This battery fits in a standard Group 27 box, but offers a little extra power. I put 2 of these in about 4 years ago and they are still going very strong.

Of course the answer to the original question here really depends on how you use the boat. I have found that I can run my fridge, stereo, etc all day and then run the fridge and a fan all night (and occasional lights, vacufulsh, etc) and still have cranking power the next morning on one of my 29s.

MLauman
09-21-2007, 08:04 AM
Would you feel ok using a deep cycle to start you engine?
Been using the dual-purpose Interstates to do that for many years.

RjVA
09-21-2007, 08:37 AM
This guy would agree with the use of deep cycles....


http://www.yachtsurvey.com/boat_battery_basics.htm

Sorrento 25
09-21-2007, 09:18 PM
Sorento 25

You said:

"Optimas are great cranking batteries but do not have much capacity as a house deep cycle. I have one for a cranking battery."

The Optima D31M is a larger body marine battery with 900 CCA and 1125 CA.

I use two of the yellow top versions for my Motorcoach in deep cycle mode and two more for starts and have for years. What marine requirement are you thinking of that makes you say they don't have much capacity as a deep cycle battery. Am I missing something?

Very nice schematic by the way...They excel at cranking and put out tons of power instantly, but you wouldn't want to use them for house or inverter batteries. Its the amp-hours ratings that are weak. My blue top D34M Optimas are rated at 55 and even my cheap deep cycle house batteries are rated at double that - 110 each. The D31M is only 75. My two 6V Trojans are 420 Ah.

If they supply enough capacity for your deep cycle house or inverter needs they're a great battery, but a flooded deep cycle is still your best Ah/$ value.

LtCdr. Augs
09-25-2007, 10:52 AM
Thanks for the detail and good points.