Absorption Glass Mat sealed battery

[Sundowner]

Hello again fellow boat owners. I am in the process of re equipping my boat with a new battery. I have had a look on the net and it seems that nowdays we have a good selection to choose from. I rather fancy the new maintenance free Absorption Glass Mat sealed batteries but have not been able to big up any dirt on them from actual owners who have them fitted. The spec's look good on paper and the sales blurb is all sunshine and happiness but they cost a arm and a leg. I'd welcome your comments on this one.
Ray

[lurch]

Hey Ray

I work with batteries all day , for use in golf buggies , and can lend some insightfor you .

AGM batteries are a valve regulated battery made up from glass matting soaked in an acid solution , surrounding lead plates , much the same as a regular battery . the difference is that u cant refill them and therefore they cannot spill either .
This can be an advantage depending on the intended use of the battery . if they are being transported from boat to garrage to charge or if being tossed around in the vessel they wont leak.
There is however not necessesarily any great performance advantage in having an AGM battery over a conventional battery for general use where you have the battery being charged by the motor and u arent deeply discharging the battery regularly.
You could also consider the GEL type batteries these are better generally than the AGM batteries but are more expensive again.
What are you intending to use it for ??
Electric motor
Sounder and lights
Starting your motor

The best advise would be to shop around for a price and most importantly check the warranty given if it isnt any better than a normal battery i wouldnt expect it to be any better performance

Peter

[Payneful]

Gday Ray

I would have to disagree with peter that Gel batteries are better than AGM. Gel batteries are very susceptible to "drying out" and need a lower charging voltage to prevent this. Most charging systems in boats and cars are set up to charge at 14.4-14.8V, manufactures of gel batteries recommend a charging voltage of 14.0V. Thus would suffer overcharging problems if connected to an unmodified system.

AGM batteries have several advantages over normal "flooded" cell batteries. Firstly the most important feature of them is their ability to supply high cranking amps and still retain the deep cycle ability. Secondly the charge rate that they can take, this equates to faster charging times. The advantage in this is that if you are doing drifts all day and constantly starting your motor only for a few minutes at a time a normal "flooded" battery would not get a chance to fully recover (from the starting of the motor), however an AGM battery would almost be fully charged in that few minutes, or at least a hell of a lot closer than the flooded cell.

AGM batteries also have a lower self discharge rate, this means that if you only use your boat every month or so, the battery will have a higher state of charge than an equivalent flooded cell. The advantage in this is the likelihood of damaging sulphation is reduced.

They also have the advantages that Peter outlined above. Now with a battery with all these advantages, it has to have some disadvantages (can't have the cake eat it too), the only disadvantage it their price. An 80 amp hour AGM battery will set you back around $270-350 depending on where you buy it from. An equivalent flooded battery such as a century marine pro 600 will set you back around $150-160 roughly half the price.

Hope this helps

Sam.

[Sundowner]

Thanks guys, you have been a help and I appreciate it. I run my boat out from Hervey Bay and usually cover a lot of ocean when I'm out fishing or just cruising. However, my present battery is 4 years old and I intend to give it a capacity check to establish just how much storage capacity it still has. I do have long lay up periods as I stay 3 hours drive away from the bay so its a case of having to making time to get on the water.

I fully understand the dangers of plate sulphation. Its happened to me before. I dont want a dead battery while out in the northern bay so I try to keep ahead of problems. $300 is a lot but then so is a tow from VMR. And then there is all the embarrassment! :-/ I think that the fact that lay ups will not be a major factor in the battery's life cycle is a big plus. I have heard that there is an American battery that enploys a spiral plate design and has reduced the overall size of the battery for the same CCA! Will have to have a look and see if I can find out more.

Was interested to see if any boaties out there were using these type of batteries.

[Morlers]

Ray, I have the solution.

Buy an ordinary marine battery for say $150, join VMR and pay petrol levy for say $5+$44 and invite me along with my boat each time you go out. If problems happen then I can tow you home for a carton or you can tow me home for a bottle of brandy. How's that? And all for less than $200! ;D

:) :)

Morlers

[Kerry]

I have heard that there is an American battery that enploys a spiral plate design Them are optima.

Batteries :-X well they all will die, sometime - and having a second battery (called independence) gets justified and the thumbs up when #1 dies.

Cheers, Kerry.

[Sundowner]

Morlers, I like your way of thinking 8) Sounds like a Bundy solution to me. Will have to take you up on it next month.

[Sundowner]

So has anyone out used optima batteries? Any comments on them? ???

[Payneful]

Ray

Optima batteries are excellent ... We have some that are around 8 years old still going hard. Exactly same technology, just done in a spiral fashion.

Sam

[littlejim]

Payne,

how do keep check of the charge in the optima?
Had a look at them once, thought that despite the expense they might be lighter (not so). Asked whether there was any easy way to check charge state, told no. At least with the lead-acid batteries I can use a hydrometer to see whether it is on the downhill run. Like to find out at home, not on the water.

[Sundowner]

littlejim you can have a capacity check carried out on any lead acid battery and I am including gelcells and maintenance free types in this as well. The test consists of an applied near sort circuit across the battery for a fixed period of time. When I say near short I mean that the battery current flows through a known fixed resistance and the voltage is measured during the test. Idealy the voltage will drop only slightly over the period of the test thus indicating the capacty remaining in the battery. Most battery specialists have this sort of test equipment and they will carry out the test for you at a minimal cost.
If you have any worries as to the health of your battery this test will settle matters for you.
A hydrometer test is Ok so far as it goes but that still wont tell you how much charge the battery is capable of holding. Then theres the possiblity of error when reading the the Hydrometer as well as the calibration of the float used in some of the cheapies that are out there in the market place. The best test of all would be to do a full discharge test but that takes a lot of time and setting up to do it.

[krakatinne]

sundowner sounds like a lot of money of 1 battery forget the fancy stuff DUEL batteries ar best

[littlejim]

Thanks Sundy,

any ideas on on how often you'd do it for the Optima? Say first one at 3 years and some reasonable time thereafter? Other question- with the Optima do you keep it on a trickle charger to make sure it is full, or rely on a voltmeter to tell that it is fully charged? Currently I rely pretty heavily on the hydrometer to tell me what is going on with the lead-acid battery.

[murrayscod]

ive been using AGM batteries to run my nav lights and leccy motor for about a year now.. and love them.. yep they seem to last long time, charge quick, smaller than usual battery, and no worries about leaking acid. got one wired up as a dual battery system in the patrol and also another one in the offroad camper trailer. i got a 90 amp one for $ 90 brand new of ebay... whereas another one was $250 from a battery place. nothing wrong with either so pays to look around.
cheers Luke

[Payneful]

A Reasonably accurate way of measuring how much is left in your battery is by the use of a digital voltmeter. Have a look on the web for the exact voltages that correspond to State of charge, must have no load on the battery (although there are graphs that show state of charge vs voltage for different loads).

Sam.