Need New Batteries

[ddsailor25]

I have been reading alot of the older post and just want to get a quick oppinion. My battery needs are minimal. Besides the usual light, radio, and gps my biggest power needs are an auto pilot of which I will only really use during powering. I'm leaning towards two gel batteries. My charging capabilities are the alternator only at the standard 40 amp at 14.4 volts. I do have 5wt solar panel, but I think I'm going to stop using it because it puts out 19 volts and I don't want to spend $400 on batteries to damage them. The boat is used every weekend from June through Sept and usually 2 week long vacations. There is no shore power hook ups and therefor no chargers. I'm also looking at a battery combiner for charging as well, unless it's really not advisable.

Thanks,
Dave

[btrayfors]

Dave,

In your particular case, gels might be a good solution. With no charging source during the week, their very low self-discharge rate would be a plus. On weekends, when you run the boat, the alternator will top them off OK.

Gels are indeed sensitive to over-voltage charging, but I doubt seriously if a 5W panel would do any damage to a sizeable gel bank (I assume over 200AH). 5W @ 19VDC is only 0.25A....barely a trickle charge when the sun is shining brightest.

AGMs also have a low self-discharge rate, but really need to have a full charge every couple weeks or they'll sulfate badly.

With no controlled charging source aboard during the off-season, I'd plan to take the batteries off the boat, and store them somewhere you can give them a full charge every few weeks.

Treat 'em right, and gels will last a very long time (witness the two 13-year old golf-cart gels in my basement, which spent their first 10 years on a sailboat. They are still very good.

Bill

[Highlander40]

Dave , The jells will do the job but the standard alternator output voltage of 14.4 V is too high. You need an external regulator that is programable.

Standard wet cells will drop right in for less total cost and if you use the boat every week there should be no problem with self discharge.

[DaveOnCudjoe]

Dave,
I, too, am shopping for a new battery. My F-31 is very weight sensitive so I'm limited to 1 battery of which I've decided to go with a wet cell 12v( as opposed to 2 6v)in the 100ah range. I'm replacing an AGM and was shocked at the price differance between wet, AGM and gel. I charge with 100 watts of solar through a controler. Wet cells work for me due to low angle of heel but I'm told that there are aftermarket cell covers that will prevent electrolyte from spilling if heeled deeply and allow wet cell use where gell or AGM designs may have an advantage. Dave

[ddsailor25]

Any sugetions on a programable regulator that won't break that bank?

Dave

[Highlander40]

Ha Ha, can't be more than one or two BU's (boat units, $1000.)
Break Out Another Thousand, BOAT.

No really, There may be an issue with the present alternator and whether you can add the external regulator. I just put in a Balmar alt. and reg. not cheap.

Thats why I said to stay with lead acid. Maybe you can get a maintenance free or sealed battery.

[forsailbyowner]

I've been looking at building an adjustable voltage regulator. I found some plans online from an amsterdam houseboat site. Parts were only about $15 to build. With my large battery bank it would be nice to crank it up for short hops to recharge, and be able to drop it to a good float voltage for when batteries are topped up.