Dual battery

Battery longevity is determined by discharge/recharge cycles, and Depth of Discharge. Battery longevity has everything to do with how you manage them. This is particularly important with AGM’s and other Lead Acid type batteries. If you do not let them drop below 12.5 volts they will last much longer than if you let them drop to 12.3 volts.

Macca.

Optima say you should keep a battery above 12.4v so why would you deliberately run a battery down to 11.5v which can diminish it's capacity and shortening it's life that doesn't make sense to me but I'm no battery guru either.

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Yes Batt's, "keeping" a battery above 12.4 volt is good practice, but it will do no harm to go down to 12 volts so long as it is rare and not "kept" there but promptly recharged.

I actually meant to say "12 volts" but had "11.5" in my mind as that is the usual cutout setting of a fridge.
I doubt that Lloyd had a voltmeter available to test battery level on discharge so suggested using the auto lo-volt cutout of the fridge instead, as a sign of battery depletion. Sometimes, compromises are necessary even if it means bending the rules. lol

Rules bend, it is records that break.
Too many people take rules of thumb as law, but thats forums for you.
How many times do you see batteries run down and forumites( not necessarily this one) advise the poster to throw it away.
Makes me wish I still retailed batteries.

No worries Allan B

Nothing to do with forums qldcamper just info from battery companies maybe they`re wrong about their own products.

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Well, as to data, specifications and recommendations, you need to remember that they are endeavouring to sell a product in a competitive market. So..................!

People put bigger wheels on stressing drivelines, steering and brakes then chip the engine depleting the manufacturers safety margin but heaven forbid letting the deep cycle drop below 12.3 volts because thats what the supplier said.

Yes but does that mean if you do mods to your own car beyond spec and have no problems that you can confidently tell others they will have no problems not knowing how they drive or treat their vehicle or how well a battery is looked after or how often it gets used. Or do you inform them that it comes with possible risks that's all I getting at.

QLD
Isn't towing a trailer similar/same to fitting larger wheels/tyres, no more stress on the driveline other than that already able to be applied bt the power unit. While steering may steering affected? and it is simply the brakes are less capable of stopping the same weight but are they really stressed more than is normally possible? Not sure it is a true analogy to battery discharging.

Yep and then they go and to as well.
If people wish to believe that if they run their battery down to 11.5 or lower once or twice they need to replace it then its up to them.
Miss information that is parroted on forums is responsible for a lot of money being wasted.
Go on a caravanforum and say you accidentally left your fridgo on over night and run it down to 10 volts and ask the best way to recharge it.
You can bet within the first dozen answers one will come up saying " throw it away you have killed it".

Yeh, if you let the battery run down to 10V, you certainly could kill it, even if it was the 1st time you did it. But unlikely.
I've had one car battery in the last 40yrs just cark it, but all the others usually give you a warning, like slower cranking, the same as AGM's, they won't run the fridge as long as they used to until the battery gets down to that magical number......12.2.....12.3.....12.4......?

If the battery hasn't done anything different to the last 4yrs I wouldn't even give it a thought.

I've recently replaced the 2 starters in my 200 series with Century ( Aussie made ones ), mainly because the Toyota dealer ( cheaper price than the auto stores ) only stocks that brand.

As you said, quality these days is hard to find.....and too many still trading on the hype surrounding their supposed good names.

Gronk,this is a question not a challenge, because I am trying to update my knowlege on the subject.

10 years ago no batteries were manufactured in Australia. They manufactured the polly case in Australia which they showed the process of and they fitted the cells and glued the lids on but production of the cells wasnt allowed any more some time prior to that because of cost and hazardous wastes. At that time all Australian assembled batteries sourced their cells from a small hand full of manufacturers. Most even imported the cases too hence many different brands having the same case but vastly different inners.

Has this changed allowing claims of Australian made or are they still Australian assembled with a minor component locally produced?

I can't answer that 100% ? Googling Century only comes up with them saying made in Australia...Queensland I believe.
They say manufactured and built in Australia, but take that any way you like ??

Century are manufactured (Assembled) at Wacol a Western suburb of Brisbane, if the components are also manufactured in Australia, I don't know but could easily be from completely imported components. They also have a retail outlet there.