Sunday, Jul 30, 2017 at 00:09
As you may have heard me say before I believe that AGM is being heavily oversold and may have no advantage at all to the customer, but will yeild the seller more that twice the profit that a similar flooded battery will.
AND there are heaps of people on the AGM band wagon ....... some of them buying cheap chineese crackers and slapping a label on them .... Don't get me wrong there are some very good batteries coming out of china ...... but there is plenty of crap too.
The unfortunate truth is that heat kills batteries and degrades every performance factor measurable.
the optimum operating temperature for any type of lead acid battery is around 20 to 25C .... below that the cold slows the chemical reactons till at some point they simply don't work at all .. above that and every degree above that degrades the life and performance of the battery ..... regardless of price or construction.
One battery manufacturer states that battery life is reduced by 50% for every 10deg above 25C ...so 35C 50%of best, 45C 25% of best, 55C 12.5% of best and so on. .... 70+C ..... HELL
heat is realy realy bad for batteries and probably THE worst place a battery can be located in under the bonnet.
Just to hammer it down hard ...... heat kills batteries.
Anyway, if you are going to kill a battery why kill an expensive one.
Thousands of AGM batteries are sold into a certain early death each year.
If ANY battery salesman tells you that their AGM is fine under bonnet ask them to show you the battery live V temperature curves for that battery ..... betya they have never seen them, nor know where to find them.
But they will take your $500 with a confident smile.
Yes there are AGM batteries that have better temperature tollerance than others.
One commonly sold AGM battery lists a maximum recommended operating temperature of 45C, with no other maximum operating temperature stated.
The same manufacturer offers another series of AGM batteries with a maximum recommended operating temperature of 55C and an absolute maximum operating temperature of 71C ... assuming temperature compensated charging ...... BUT offers only 55C as an absolute maximum without temperature compensated charging. .... so unless there is a temperature sensor on the battery we are back to 55C.
The above may not be universal but would be typical.
There are also vehicles that have higher under bonnet temperatures than others. .... so hows that 70C+ under bonnet sounding
So these guys that are offering Guarantees for under bonnet use of AGM are playing the odds. ..... OH YEH .... ask them for the terms of their guarantee in writing before you part with your cash.
The other thing when selecting an AGM battery ...... look and ask for spec sheets, if they have not got em or don't publish em .... don't buy that brand ..... I mean sheet with performance curves, recommended operating temperatures and real technical stuff not just a table of sizes or a glossy brochure.
OH yeh ... buy a battery that has the same name stamped on it as is above the door of the factory .... at least you have some thaught that the bloke who made it thinks it's OK.
ANYway back to recomendations.
I'd strongly recommend a sealed maintenance free rugged construction battery that may be sold as "marine", earthmoving", 4WD, or "enhanced flodded cell" battery ..... that will have most of the good technologies of AGM, but they did not tip the spare acid out before they sold it to you.
I have had a good run with "Supercharge seamaster gold", yes the Catapilar batteries continue to have a good rep but pretty much any good sealed maintenance free wet cell battery will last better than AGM in a hot environment ...... even if it does not it will cost you HALF what a similar quality AGM will.
Don't get over obsessed with "Deep Cycle", it probably does not mean what you think it does.
hope this helps.
cheers
BUT above all .... ya gota do something about that temperature ...... you are likely to double the real life of any battery for every 10C you reduce that temperature till you get to 25C.
AnswerID:
612758
Follow Up By: Member - William B (The Shire) - Sunday, Jul 30, 2017 at 12:03
Sunday, Jul 30, 2017 at 12:03
Hi Bantam,
Thank you and also Allan B. for a interested read re. batteries.
I have a 4 year old Supercharge 4WD battery under the bonnet of my Prado.
It was recommended to me by my auto electrician because of the reason that I only had room under the bonnet and we usually only stay in one place for 2 days at most and drive every day when touring.
It is a 850 CCA rated battery and is still testing at around 700 CCA.
So far I am happy with the way it performs and its long life, if I was going on a Canning trip I would probably replace it, but it will stay there for the moment.
William
FollowupID:
883131