AGM Batteries.

[bedouin]

Re: You need to do a bit more research...

I find the "unlimited current" claims a little disingenuous in that in most systems it is the voltage that is limited, not the current.

In my view on a sailing boat the most important factor is the speed at which you can replenish the batteries - I'd like to be able to compare the time it takes to raise AGM from say 75% to 100% (at 14.4V) with that for flooded batteries at 14.8V.



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[Ships_Cat]

Re: You need to do a bit more research...

I agree with you.

While some AGM batteries have gone into boats I have managed I have never taken much notice of the charging times (they have been power boats with generators and just been installed because of convenience and wealthy budgets rather than for any charging characteristics). From what I can see the absorption charge is just like a wet battery in that the voltage is limited, as you say, and the charge current takes a big dive as the battery's voltage comes up - the few charging curves for them that I have seen show that to be so.

John

<hr width=100% size=1>I am the cat but I am only 6.

 

[cliff]

Re: You need to do a bit more research...

Not really but there again I do not call reading sales leaflets or sales orientated literature as research - of course anyone trying to get the punter to part with cash will claim their product is the greatest thing.

Let's try charging an AGM or gel battery at 16v (15.8v) and see what happens and how long it lasts. Neither AGM nor GEL cell batteries can be topped up and "over volts" will kill them very quickly unlike the good old wet cell which can take a fair amount of electrical abuse.

Granted AGM / gel do have some advantages over wet cells but do I want a battery to work upside down or do I want a battery that will suddenly die on me rather than "get tired" and give me some warning of impending collapse.

Finally if they are so good are the railways fitting them to the trains? are the telecoms companies using them in their standby power facilities or are they staying with the old technology?


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[pvb]

Don\'t just rubbish product claims...

You seem to be very distrustful of manufacturers' claims and other people's views. I wonder whether you've considered the fact that most AGM batteries come from respected US manufacturers and that, as the US is possibly the world's most litigious nation, their marketing literature tends to be fairly reliable. I think we all acknowledge that AGM batteries aren't suitable for everyone's boat, but the fact remains that they perform brilliantly if used properly. As I said before, your statements may mislead other forum users who are considering using AGMs.


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[LeonF]

Lots of learned information. I replaced the conventional batteries on my previous boat with AGM batteries. They were fine..I used an Adverc regulator. But I then found that when fully charged by the mains charger they overcharged when running the engine.. as high as 15.1. neither Adverc.. which I first suspected to be the culprit..or the supplier could offer a suitable explanation.. see previous postings..I replaced them with conventional batteries and got my money back after a fight. Problem solved..

<hr width=100% size=1>L.A.R.Ferguson