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rbyham 01-18-2013 08:16 PM

Battery Recommendations
 
New boat needs all batteries replaced. The current setup is 3 batteries total, one for cranking the Atomic 4 with oversized alternator and 2 house batteries. My electrical needs are pretty standard - lights, tunes, VHF, anemometer, occasional autohelm plus I want to add a couple of fans for summer use sleeping aboard. I am thinking flooded. Would love to get recommendations here for cranking and house batteries.. Any good deals out there that I can take advantage of?

benesailor 01-18-2013 08:42 PM

Re: Battery Recommendations
 
it sounds like basic needs. Not sure how much time on the hook you plan on doing. If you live near a big city shop around at some big battery suppliers. You would be surprised what kind of deals you can get. I've seen used AGM's for a third of the price. These were 1-2 year old batteries rated for 7.
What type of charging system do you have? Something to think about.

PorFin 01-18-2013 08:54 PM

Re: Battery Recommendations
 
Recommend you take an overall systems approach to this, since you could easily wind up with a battery bank that is ill suited to your needs, your charging capabilities, and/or your wallet.

What batteries are currently installed?

What size alternator do you have?

Is there a battery charger installed? If so, type/model would help.

What are your sailing plans? Mooring? Anchor? Dockside power?

rbyham 01-18-2013 09:04 PM

Re: Battery Recommendations
 
Thanks all. I will be in a wet slip with shore power. The boat aslo has a charger but I am not sure of make or model. The boat has no batteries at this point so I do not know what was there previous. But there are two cases and all wiring for two in the bilge and one battery case all wired to the Atomic 4 that sits in the port lazarette. So the cases and placement are set. All I need to do is drop batteries in and connect. The alternator is described as upgraded/over size but I have no idea how to determine what the level of output is. The boat is also wired for a solar panel. Wiring is there and controller but solar panel was toast. I plan to replace it but not sure how big that needs to be either. I will be using the boat basically for day sailing with the occasional weekend spent aboard.

chef2sail 01-19-2013 10:44 AM

Re: Battery Recommendations
 
I would go with 1 house bank and a seperate starter battery echo charged off the house bank. Do you have am AB or combiner switch? Stay wet cell for all the batteries ( they are cheaper to begin with, but need some maintainence in terms of water added. Your charger should also be a 3 stage one.

I would go with2- 6Volts for the house bank and a small group 27 12 volt for the starting battery (you have a 12 volt system so it takes two 6 volts to equal 1 -12 volt battery)

Over simplifying battery are compared by amp hours at 12 volts. The two 6 volt batteries will take up just a little more room tha 1 12 volt group 31 batery with twice the amp hours. ( 220 ah vrs 110 ahs). On your batteries you only get to use 1/2 the ah rating before they are dead.

Sound like you boat is set up for two gorup 31 which will give you 220 ah. Ill bet you could fit 4 -6volts in the same space and get 440 ah which is a large amount. The single battery spot is the starting battery probably battery

The best thing to do is fingure out your electrical diet for your house bank per dday. That is how many amp hours you use. For instance 1 light ( non LED) will us 1 ah. If you anchor and the light is on for 10 hours thas 10 ah. Same in your cabin etc. Auto helm will use 4 amps per hour. CHartplotter instruments figure 1-2 amps per hour each etc. No referigeration? Thats usually the big draw at 4 per hour.

You proabbly can start off with the basics here 2 6 voltsand a group 27 strater wet cells while you learn about the electrical part of your boat and see what. The reason I orefer 6 volts vs 12 is that the lead plates are heavier and more deep cycles, and their footproing is much smaller, so you can usually get 4 of them in the space of 2 group 31 and therefore twice the ah.

I also suggest you get some good 12 volt books and read up on the elctrical/ battery part of your boat as it is a system which you need to become learned about, just like your engine. Its not complicated, but its some good knowledge to have so you dont overspend, but have a system which matches you needs and sailing profile.

A good system will imnclude a combiner, as well as battery monitor ( I recommend Victron) , echo charger and a good three stage charger if you are the dock. You need to learn about equalizing etc.,

But for now go simple till you learn about it. 2- 6 volt golf carts for the house and 1 group 27 for the starter. You can always add two more 6 volt later. Feel free to go to Sams/ and buy them as unless you get into AGM ( I would wait) you should be able to get by for less than $200.

Dave

Good luck and feel free to ask away here there are lots of knowledge and opinions too

BELLATRIX1965 01-19-2013 10:57 AM

Re: Battery Recommendations
 
What the Chef said! Keep it simple!

Plus 1 for the 2 golf cart battery house bank and 27 series start battery idea. Flooded batteries should be fine for your use. I like the Trojan T-105s for the house bank. Since you are day-sailing from a slip with power, I would not even bother with the expense and clutter of re-doing the solar system. I agree, though that you should invest in a GOOD 3-stage charger and a battery monitor. Use the money you save on the really important stuff - like sheets and sails and winches!! Have fun!

CalebD 01-19-2013 03:15 PM

Re: Battery Recommendations
 
This is a decent primer on marine electrical systems: BoatUS - BoatTech - 12 Volt Electrical Systems
Several articles on that site will be of interest to you: BoatUS - BoatTech - Electrical

As to your alternator, the A4 came with a stock 35 amp alternator. Moyer sells upgrades that are either 55 amp or 120 amp. There may be a spec plate somewhere on your alternator or some other identification which can help you figure out the amperage charge from your alt.

The basic rule of thumb is that your alternator should put out > 25% (in amps) of your battery banks total Amp Hours (AH). So a 55 amp alternator would be fine for charging a 200 AH battery bank. A 120 amp alternator should handle a 400 AH battery bank etc.

Check places like Sam's Club, Costco etc for deals on deep cycle batteries. You will pay through the nose for these at a West Marine or other chandlery.

6V batteries are great if you have the room to properly store them on your boat. They need to be in boxes which are strapped down to the hull. Unprotected battery terminals in a bilge is a big No-No.

BarryL 01-19-2013 03:39 PM

Re: Battery Recommendations
 
Hey,

Keeping it real simple, go to your local costco (assuming you're a member) and buy 3 of their Marine batteries (costco 27DC 115AH. 750 MCA). For day sailing and an occasional overnight trip you don't need anything fancy. They cost around $80 each.

Barry

chef2sail 01-19-2013 07:44 PM

Re: Battery Recommendations
 
Was at costco today 2 6 volt batteries 240 ah total are $90 each
goup 27 $ 105 ah was $89. The golf cart batteries as a rule have thicker lead plates cells and will take more deep cycle charges. They will take 1/2 the room of two group 27 so if you want to eventually add two more you will have the space. Only retsriction may be thier height so measure and check before you buy.

In addition they all should be tied down and in boxes if wet cells.

Check the most recent MaineSail thread s far as orientation as he has brough up a good point about keeping the cells covered with acid while the boat heels. AGM you dont have to woory about this as you can store them on their sides if necessary.

Oaksail 01-19-2013 08:13 PM

Re: Battery Recommendations
 
Quote:

Originally Posted by chef2sail (Post 978176)
Was at costco today 2 6 volt batteries 240 ah total are $90 each
goup 27 $ 105 ah was $89. The golf cart batteries as a rule have thicker lead plates cells and will take more deep cycle charges. They will take 1/2 the room of two group 27 so if you want to eventually add two more you will have the space. Only retsriction may be thier height so measure and check before you buy.

In addition they all should be tied down and in boxes if wet cells.

Check the most recent MaineSail thread s far as orientation as he has brough up a good point about keeping the cells covered with acid while the boat heels. AGM you dont have to woory about this as you can store them on their sides if necessary.

I believe when you wire batteries in series you double the voltage but the amp hour capacity remains the same.
Eg. 2 x ( 6volt, 240 amp hour) = 12 volts at 240 amp hours.

When you wire batteries in parallel the voltage remains the same but the amp hour capacity doubles.

You don't get the same capacity in half the space with 6 volt batteries.


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