looking at batteries

[fred1diver]

hey everyone, I'm looking at buying a new battery for my boat. It is confusing, there are so many different models and ratings.
I mail use power for the sonar(fish finder), marine vhf, anchor light, nav lights (rarely use them), steaming light (again rarely used), cabin lights and charging the iPhone and iPad.
I'm looking at a group 31 battery at 800 marine cranking amps, 105 amp hours, 185 minute reserve capacity. I don't get the reserve capacity
I looked at 4D batteries and they seem interesting, well, a part form the price, would that be overkill for my needs?
what should I look for?
help me
thanks in advance

 

[Ron20324]

If you have just a 4D and it dies, you got nothing. With 2 x 12, if one dies you still have the other. Other folks will say 6v are the way to go, but you'd need 4 of them, I'd say.

 

[Allan12210]

2 x 6 V will give you in excess of 200 amp hours. For the price/amp hour it is the best price option. You could expect over 800 charge/discharge cycles against around 350 cycles for either 4D (really heavy battery) or a Group 31. Mine are 7 years old and still seem fine. For additional piece of mind, you could add a small (Group 24) that's just dedicated to starting the engine, but could get you home if the house battery went flat (pretty unlikely based on the description of usage you gave). I like my 6 volt system. Switch all your lights to LED. Search the archives for Mainsail's discussions. It will be very enlightening to you. Give yourself a little time as you will be tied to your decision for quite a while.

 

[Roland5048]

I have 4 X 6V. Trogan 105s for house and a Group 24 to start a 3YM20. Way over amped for my needs but I can get 10 years out of them and when we are anchored out we have no issues.

 

[sailnewbie]

I bought 2 Napa deep cycle #27 I believe, and they run my boat for almost 4 days and I run alot of stuff for the kids, TVs,12 volt cooler, fans,lights,fish depth finder, auto pilot, radio, vhf but also use the little solar charger to help keep up

 

[puffcard]

The Reserve Capacity (RC) is a very important rating. This is the number of minutes a fully charged battery at 80 ° F will discharge 25 amps until the battery drops below 10.5 volts.

One battery that would be worth a look is the 12VDC golf cart battery, same footprint as a Group 31, but 2in taller and has 155 amp-hrs. The one I have is made by US Battery cost about $125, has 50% more capacity than a group 31 for $25 more. Then use a sealed AGM for the starting battery.

http://usbattery.com/products/12-volt-batteries/us-12v-xc2/

 

[Chief RA]

Looks like your demand per use hour will not exceed 5 amps. While more expensive than buying one size 24, 12 volt: buying 2 ea. 6v batteries is a viable option. A 80w flex panel to lay and tie on the deck in clear sun would be adequate . Using your existing battery is a good cost option as well. Having a 2nd battery may not be needed as your amp demands seem to primarily coinside with an active solar panel charging in the sun. In the unlikely event that your battery runs low, your boat functions fine without it until the sun reappears and recharges your battery. Backup can also be achieved with a jump starter battery unit such as Amazon's Jump-n-carry,JNC300XL, 900 amp at only $65 bucks, This unit can readibly be recharged by hooking it up to the house battery. Can also be used for many purposes.

While the input from all is well intended and trying to help; be aware that almost all are from Skippers of boats much larger than yours and tend to think larger systems with electric starting,water pump, toilets, reefer, TV, etc..
Hope this helps you make a sound decision based on boat size and your uses.
My best, Chief

 

[fred1diver]

thanks everyone, so far I'm leaning towards a group 31 battery, then maybe in the future a solar panel

 

[Tally Ho]

My 2cents...if you fit 2 group 27 or 31's, that gives you some redundancy if you use 1 batt at a time. This would primarily be important if you need a battery to start your engine.

Don't ask me why I think this important...just assume I needed a tow after running the battery down. Now I carry 2, use 1 at a time, and carry a jump start pack.

Greg

 

[fred1diver]

I have a manual start motor on my boat, at the moment I have a group27 on board but it won't fully charge, so that one is going dead on me, so I need to get another battery, for the usage I have, I won't need to wire them both, just replace the battery with the fresh one and continue my trip, hopefully with both I'll be able to take my 7-9 day trip

 

[Chief RA]

Fred: Hooking the bad one in parallel with your new can ruin your new one, so be careful with that. The new one will keep charging the old one trying to bring it up to full charge. I think you are saying your just taking the old one in case you need packup power. Have a nice trip. Chief

 

[Brian S]

Cold cranking amps is a useless specification for the kind of batteries we need. It's a starter battery, even if is says it's dual use. What you want is a true deep cycle battery. Starter batteries are designed with lots of thinner lead plate (even foamed lead) to provide lots of surface area for large amounts of current for short periods of time, that are then recharged all the time. When batteries like these are drawn down, they will die premature deaths. A deep cycle battery uses thicker lead plates, and does not provide large amounts of current - but they provide continuous current, can be drawn down and recharged many times.

You owe it to yourself to research batteries at Maine Sail's forum: http://forums.sailboatowners.com/index.php?forums/musings-with-maine-sail.135/ There is a lot to research and digest on his forum, including info about type of solar panels and chargers.