battery help please...

[Rich (P303)]

Question is what do I need??? I have a 1984 Pearson 303; 2 group 27? or 29? (can't remember which if there is such a thing) 5 year old GEL's in a battery compartment. House battery will not hold charge for very long now.I was hoping I could go a little bigger if the battery box will allow. I plan on getting 2 AGM's. My engine is a Yanmar 2GMF with a 30 amp alternator. All I have for a set up is Off/1/Both/2 for the selector switch.I do not have any kind of battery maintenance system for charging. Just a prehistoric volt meter that will let me know how much each battery has left.Can I overcharge the new batteries off the alternator?... or does the alternator stop charging (like a car) when batteries are full.I am on a mooring, power needs are minimal besides cabin lights at night. We need to motor 1/2 hour to reach sailable waters each time.Any recomendations would be helpful, first season with a big boat.Thanks,Rich

 

[Don S/V ILLusion]

some ideas

RichThe most often misunderstood reason why batteries die prematurely is because they are constantly undercharged. A 30 amp altenrator with internal regulator will never overcharge unless the regulator is bad but with only a short run time periodically. it will also never fully charge batteries. There is lots of stuff here in the archives which will explain in detail the fundamentals.Your OEM (?) alternator will cut back upon sensing a higher voltage on the batteries thereby precluding damage but can and does also result in undercharge.You might want to consider solar or wind generators to augment the charging after buying new batteries. Also,unless you have a good reason for AGMs or Gels, they may not be worth the extra $$$

 

[Rick1198]

Charge

You did not say how much you use the boat. I would go with new 27s and a solar system.YOu can put a good solar system in for under 500 that should keep every thing topped off. and runn good. If you really dont use the boat that much, you can go a lot less on the solar..rickSV/Sirius

 

[Rich (P303)]

Rich... boat use

is only every weekend (weather permitting) from mid May to the mid October... with maybe a week or 2 of extended cruising. No fridge, no generator... just some electronics and lights.

 

[Stu Jackson]

try the West Marine Advisors

about battery systems and charging methods, catalog or on-line

 

[Ross]

I use 2 group 31 AGM batteries.

I install them watch their voltage with a digital volt meter, charge them with a 50 amp alternator which puts 14.2 volts at the batteries. First set lasted better than 5 years before they started to fail. When I changed them it was the first time I had seen them since they were installed. There was NO corrosion around the terminals, everything was was as bright as when I installed them new. That alone is worth a little peace of mind. They will hold their charge over the winter and start the engine in the spring without the need to connect a charger.If you have room go for the biggest batteries that will fit, motor a little more, it is good for the batteries and the engine.

 

[Benny]

It seems you have small power needs.

No refrigeration, deck lights, inverter or other large power drains. I would go with two group 27 lead/acid deep cycle batteries. Save the extra money the AGM's would cost and get a solar panel and controller to supplement the charge from your alternator. Being your first season with the boat familiarize yourself with its electrical system. Of importance would be to find out if the bilge pump is hardwired allowing you to shutoff the Battery Switch when the boat is not in use.

 

[Landsend]

I'd go two type 29 lead acid and upgrade the

alternator to at least the 55 amp.

 

[DJ]

Go with Lead Acid

I'd stick with flooded lead-acid batteries and invest in a bigger alternator or better yet a modest solar panel with controller. The panel would do you better at a mooring. AGMs are nice but how often are you going to use your boat? You did not say where you keep your boat. The existing 30 amp alternator may be a bit week for charging the two AGMs (you can charge AGMs very rapidly but at a set voltage) let alone group 31's. If all you use your house battery for is lights and instruments, two group 27's should do you well. If you want to upgrade your batteries, think about two 6 volt 220 amp-hour golf cart type batteries. I got two Trojan 6 volt T105s from a Truck Parts Store (they are around most major urban areas) at a great price (I think about $65 each). Don't go to West Marine for Batteries (or any boat store for that matter). Much too expensive and you can get good batteries, including AGMs at most Battery Stores.

 

[Chuck Creel]

batteries/solar

Rich,For what its worth, I have a hunter 30 and often go on extended overnighters ,. Sometimes 2 or 3 days away from dock. Sounds like your power needs are a little lighter than mine but here is what i have.2 grp 27 for house batteries, 1 dual purpose starting battery " all wet cell "1 130 watt solar panel with controler to prevent over charging.This sytem allows me to watch tv, burn interior lighting, anchor light even make coffee in the mornings from an inverter.So far 3 days on the hook with no problems starting motor afterwards.Good Luck and happy sailing;

 

[sailaway78]

Stick with Lead Acid

If you go with AGM or Gel Cell batteries, you will have to upgrade you regulator and alternator to charge them properly. This will be a major expense. I would go with two group 31's or you might want to try some T 105's. I have 4 115Ah lead acid group 31's on my 37, and run the usual plus refrigeration. Running the fridge mid summer, I am good for about 30 hours with out running the house bank too low.

 

[Rich (P303)]

Thanks...

for all your help. I will mull it over the winter months, and purchase something this spring. I will have buyers remorse whatever I buy. Bilge pump is hard wired Benny.

 

[Gregg18047]

Chuck -

Which panel do you have, and how did you mount it?And to all with 2 (12v) house and 1 start battery - did you parallel the house batteries to make it one bank, or keep them separate and have all 3 batteries switched?

 

[Chuck Creel]

panel / batteries

GregThe batteries are both 12V so they have to be in parallel " neg to neg and pos to pos . This still gives you 12V b ut the Amp Hours are doubled.For example, My grp 27's are 105 AH each so 2 of them would be aprox 200 Ahrs.The panel I chose is the KC-130 130 WATTS . It provides 7.2 amps output under peak conditions and apr 2 amps under shaded or indirect lighting. There fore , even under less than direct overhead sunlight , its like having a trickle charger on at all times except at night.You MUST use a charge controller to keep from cooking or over charging your batteries.I got my system from Wholesale Solar. There are others available online but I chose them because of customer service before and after the sale.Link provided below.