Battery Advice

[Boydster]

We're going to have to replace our house batteries at some point this year. We currently have a bank of six 350ah golf cart batteries that are five years old and were on the boat when we purchased her.
Should we be sticking with lead acid, go to AGM? What about some of the newer technologies such as Lithium Ion, or would the payback just be too long to compensate for the additional cost?
We normally use our boat for eight or nine months of the year.
Most of our trips are to anchorages and last three to four days although we usually do one big trip per year of three to four weeks. We're a family of four with two daughters that occasionally bring a friend with them, so obviously we do use a fair bit of juice for showers etc.
Wondering what the collective wisdom here would suggest. - Boyd

 

[Keith]

I love my AGMs. First set lasted about 8 years with a desulphator running on them. I replaced two 8D's with 4-6volts AGMs and it made a great difference when having to replace them. That being said, in about 7 more years, I'll take a look at the new battery technologies based on what I've read here and other boating forums.

 

[skipperdude]

The biggest bang for the buck is the golf cart batteries. Amp hour wise.

Plus you wouldn't have to reconfigure the installation.

Lithium ion will last longer than you are going to have the boat.

If it were me I would stick with the golf cart. Light weight as far as manhandleing them into the battery boxes. Trust me on that I have 8D's Talk about a hernia just moving the suckers to where I can get them out.

Like Kieth said you could go with 6 volt AGM'S.
Best of both worlds.

 

[Moonstruck]

If there is plenty of room and no problem to service your flooded batteries, I see no reason to change. You are getting good service from good value.

 

[RT Firefly]

Greetings,
Replaced 2-4Ds and 6 GCs (flooded) last year. Simple, effective, fit into existing system, NOT light. Will do it again when necessary.

 

[rwidman]

I replaced my flooded cell btteries with AGMs when they failed because regular maintenance was pretty difficult. Flooded cell batteries give more bang for the buck, but in my case, the extra cost was worth it.

 

[Budds Outlet]

AGM if you are keeping the boat. 8 years or so of absolutely no maintenance and absolutely no corrosion. No need to touch them for 8 years and they self discharge at half the rate of flooded.

One less system to maintain. That's a good thing.

 

[FF]

The AGM will pay for them selves IF you anchor out and value their ability to charge very rapidly.

AND are willing to install the gear that will create the rapid charge .

Much larger alt and 3 stage V reg with temp compensation required.

Otherwise Golf Carts , and a SOC meter , and 3 stage reg will do almost the same life, 6 years at half the cost.

FF

 

[ben2go]

Here's my post about batteries. http://www.trawlerforum.com/forums/s4/flooded-vs-agm-pros-cons-6316.html

 

[Boydster]

Thanks all for the advice, much appreciated! - Boyd

 

[Aquabelle]

First, congrats for telling us just how you use the boat. That is the right starting point. It would be useful to know what charging system you have now (big alternators, externally regulated? A genset...used for how long/often) and why you think you will need to replace your current batteries: externally regulated with a 'smart' regulator and well-maintained (ie topped off with distilled water a few times p.a.) you can expect better than 5 years.
Subject to answers to Qs above, it may come down to how much of a hassle topping-off is for you. If access is good/easy and it doesn't both you, stick with flooded; otherwise AGM, with a higher cost as the trade-off. But I'd certainly stick with the 6v golf cart type.

(Li-Ion are fantastic things but VERY expensive and best left to racing yachts that value their super-low-weight; or folks who have done away with their genset and are anchoring out for long periods with big alts and sophisticated regulators.)