I am looking at replacing my inverter batteries.  Right now I have four 6-volt lead acid batteries.  Does anyone have any experience using 12 volt AGM or gel batteries in an inverter system?  Are they worth the extra cost or should I just stay with the traditional lead acid batteries?

I use a fairly small bank of AGM batteries to run my 2000w inverter and I've had good luck with them. I chose them because they're mounted on the floor of a closet inside my boat and they don't put off any hydrogen or corrosive vapor during normal operation. They put out more amp hours for their size and they don't lose their voltage nearly as fast as a lead acid battery when they're not in use. On the down side they're more expensive.
If you've ever had a lead acid battery blow up on you you'll really appreciate the fact that they don't normally produce hydrogen gas.

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joetil
50x15 Burns-Craft in South Fla

You will need to make sure you have a compatible charger if you go with AGM or gel batteries. A conventional charger will overheat them and you will have some very expensive paperweights.

Speaking of expense. Unless you have a special case like joetil, why would you go away from the golf cart batteries? They are cheap, easy to move around, and last a long time.

Everyone I know goes with Golf Cart.

Cheap at Sams Costco and/or B.J's

We have had them on all of our houseboats and they last well for about 5 yrs

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Nitrox 2005 16x68 Summerset Houseboat
Lake Lanier, Ga

Golf carts here too, for the same reasons, cheap, durable, easy to handle. However if ventilation or access is a problem AGMs might be a better choice.

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Willie
She's a tired old barge but she's paid for! http://s71.photobucket.com/alb...p;current=ef324993.pbw

I'm going to need to replace a house battery myself. Previously with the 12 volt battery I just utilized the outboard motor to keep it and the starting battery charged. I so far haven't bought or needed a dedicated charger for the batteries and the motor has done fine. But I think I'd like to follow many of you and utilize the 6 volt golf cart batteries also but I'm a bit concerned about the capability of charging them with the motor. Would golf cart batteries need a dedicated charger or would the motor be OK.?

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Respect Our Outdoor Recreational Resources
Leaving Only "Footprints in the Sand"

2003 5.3 Chevy P/U
1972 35' Crest Pontoon Houseboat
2007 90 hp. Yamaha

If you keep your charging and usage exactly the same, replacing a 12v battery with a larger golf cart battery bank will neither help nor harm your charging situation. Your battery bank is really just like a checking account with your alternator making deposits and your lights and pumps making withdrawals.

Where you might get into trouble is if you want to take advantage of the larger battery bank and use electricity faster or go longer between charges. Either one of those can cause excess heat in your alternator when it is trying to put out more amp hours. You can put your hand on your alternator while it's running now and do the same if it's running longer charging a bigger battery bank. If it feels the same, you're good. If not, it might be time for either a little Honda generator or a solar panel. It will amaze you what even a moderately-sized solar panel and controller will do for a battery bank while you're away from the boat for a week or two.

Bamby, I just had a d'oh moment after I hit send. If you have shore power when you're slipped, forget the generator or the solar panel. A small "smart" charger hooked to shore power will do a great job for you between trips. That will give you great benefit from a larger battery bank. Use your electricity up on the weekend and charge it (albiet slowly) during the week.

Ditto Endurance...

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Willie
She's a tired old barge but she's paid for! http://s71.photobucket.com/alb...p;current=ef324993.pbw

The key word is "normal operation" AGM and Glassmat batteries will outgas hydrogen if overheated or overcharged. They are a "sealed" battery also called Sealed Valve Regulated (SVR) batteries. A common misconception is that these batteries do not out gas, that is, give off hydrogen gas while charging. So people install them in places that aren't ventilated. This is a mistake. Under normal charging conditions they will not out gas, but they do have a small valve in the top of each cell that, if the battery overheats while charging, will open and release hydrogen. These batteries are very sensitive to charging voltage and temperature. Over charging will result in overheating, out gassing,
and a significant shortening of the life of the battery because it dries out the mat.

see http://newboatbuilders.com/doc...andChargers.pdf


They USCG has decided (actually about ten years ago) that these batteries are required to be in a ventilated space just like conventional lead acid batteries. There have been some rare instances of explosions during outgassing.

Frankly I would go with true deep cycle batteries. Golf cart batteries are true deep cycle batteries even though they are 6v, so you need twice as many. 12V deep cycle batteries are expensive, but in the long run worth the outlay.

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Ike
"Don't tell me I can't. Tell me how I can!"
New Boat Builders Home Page
My Boating Safety Blog
My Boat Building News Blog

Edited: 04/24/2010 at 11:59:23 PM by Ike

+1 if you have the quick charger for the inverter batteries gel and glass mat batteries will cook and be usless. If i remember correctly when I researched this about 5 years ago the point at which damage will be done is around 14vdc, and a most of the quick charges go a lot higher.(mine spikes @ 16.5vdc till they are 80% charged)

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UC FANS
1999, 52' Monticello - Miller Tyme
Port of Aurora IN

Yep. You need a charger designed for AGM or Gel Batteries. The voltage has to be regulated to the batteries manufacturers specificationsand it needs to be able to sense the temperature of the battery. Of course the people who sell you the batteries rarely tell you this.

This is the warning on East Penn's web site for Gel batteries;

IMPORTANT CHARGING INSTRUCTIONS: WARRANTY VOID IF OPENED OR IMPROPERLY CHARGED. Do not install in a sealed container. Constant under or overcharging will damage any battery and shorten its life! Use a good constant potential, voltage-regulated charger. For 12-volt batteries, charge to at least 13.8 volts but no more than 14.1 volts at 68°F (20°C). For 6-volt batteries, charge to at least 6.9 volts but no more than 7.05 volts at 68°F (20°C).
The open circuit voltage of a fully charged 12-volt battery is 12.8V at 68°F (20°C). However, as the battery charges, the building internal pressure (voltage) causes resistance to the charge. Therefore, the on-charge voltage must be higher (at least 13.8V) to overcome this internal pressure (voltage) during charging.
http://www.eastpenn-deka.com/assets/base/0909.pdf

The same is true for AGM batteries. The charger has to be temperature sensitive and voltage regulated so as not to overheat or over cahrge the battery.

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Ike
"Don't tell me I can't. Tell me how I can!"
New Boat Builders Home Page
My Boating Safety Blog
My Boat Building News Blog

Officials: Battery charger sparked boat fires

Associated Press - April 25, 2010 1:55 PM ET

NEWPORT, R.I. (AP) - Newport authorities say a battery charger has been pinpointed as the cause of a fire at a marina that destroyed two boats and damaged two others.

No injuries were reported in the fires, which appear to have started in the cabin of 1 of the dry-docked boats at Casey's Marina on Waite's Wharf.

Newport Fire Chief Peter Kirwin says the cause has been classified as accidental.

1 of the boats, a 47-year-old yacht, was undergoing restorations. That boat and the others were stored closely together in a parking lot, which caused the fire to spread rapidly.

Copyright 2010 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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Ike
"Don't tell me I can't. Tell me how I can!"
New Boat Builders Home Page
My Boating Safety Blog
My Boat Building News Blog

I appreciate everyone’s feedback.  Thank you for sharing your recommendations and experiences.  I think I will likely go with the traditional lead acid batteries.  The cost of AGM’s and gel batteries don’t seem to have a definitive payback and I don’t have any special installation restrictions.  I can charge them each weekend so a low loss of charge doesn’t help me that much.  Thanks again!