Dual Battery question

Here is the link

http://www.optimabatteries.com.au/Products/OptimaYellowTop.aspx

Hi sand man and it’s a bit of a myth that AGMs are any safer than flooded wet cell batteries ( FWC ). Your standard AGM will gas at a lower voltage than a FWC and that means you actually have more chance of cooking an AGM and when they cook, they spew electrolyte so are no safer than FWC batteries

As for gassing, again, AGMs will cook at a lower voltage but if you smell them gassing, they are stuffed. With a FWC, if you smell them gassing, you simply top them up with some distilled water and no harm done.

I can't agree with you.

NOBODY would install a wet cell battery in the back of a vehicle's cab, or in a camper.
Tip them over and they will spill crap everywhere and without venting, mere charging will create explosive gases.

No myth mate.

That is why AGM batteries are safe inside vehicles, as well as marine situations.

Never heard of anyone with problems with an AGM battery in a confined space.

Hi Sand Man and sorry but again another myth.

There is the reverse mentality that if you use flooded wet cell batteries inside the cab of a car, 4x4 or under the bed or seats of a caravan, that they need to be vented.

NOT SO.

The minimum ratio of hydrogen to atmosphere that is needed to make the hydrogen/air mix explosive is 4.1% hydrogen.

The IEEE has set a maximum safe hydrogen to atmosphere ratio of 2% and there is only so much hydrogen a lead acid battery can produce based on the amount of electrolyte in a lead acid battery.

There is a calculation put out by the IEEE that gives the minimum amount atmosphere needed to make it impossible to get a hydrogen to atmosphere ratio of 2% and this is formulated based on the VOLUME amount of electrolyte not exceeding 0.28% of the surrounding atmosphere.

Now as no battery manufacturer lists the volume of the electrolyte in their batteries ( and they don’t need to ) so unless you are prepared to empty a flooded wet cell battery and measure the volume of the electrolyte, you won’t really know the volume of the electrolyte is.

I use a VERY rough way of calculating to determine the minimum atmosphere in a vehicle or caravan or storage shed or what ever needed to be safe for a given battery ( or batteries ).

I measure the total volume area of a battery by measuring the length, width and height ( over the battery housing not over the terminals ) then I measure the volume area of the place the battery is going to be mounted/stored.

I then multi the battery’s volume by 200 and if this figure is less than the volume of the area where I intend to place the battery then, even in a worst case scenario of a total overcharging of the battery, the amount of hydrogen that battery can produce, can not exceed 2% of the surrounding atmosphere.

This calculation has a very large margin of error factored in to make the calculation safe.

This equates to the average 4x4 being able to have 3 x 100 Ah batteries in the cab and even if all 3 were cooked dry, there still would not be enough hydrogen in the cab to cause an explosion.

As long as the area around a battery is open, then ALL batteries, no matter what type they are, are actually much safer than they would be if in a battery box.

This is fact not fiction.

One more point, when mounting a battery inside a vehicle or caravan, say under the bed or seats, while you do not need to vent the battery because there is a sufficient volume of atmosphere, you still need to mount the battery in a secured plastic battery box, even when it’s a sealed battery like an AGM.

Again, all batteries will spew electrolyte if they are over charged for what ever reason, so ALL batteries should be in a plastic battery box when mounted inside a vehicle or van.

Gday Bill,
If you want to know Derek's view on a very similar subject, have a read of this thread.

Hi Phil,

Yep simple sound advice.
Obviously any battery may malfunction if the charging equipment is not up to scratch.
But that situation is very unlikely to happen by recharging from a vehicle alternator.

AGM batteries, IMO are the safest and most practical deep cycle batteries to use inside a vehicle.


Bill.

Bill,
While AGMs have a great safety record, I wouldn't advise fitting an AGM inside a vehicle because the dodgy handywork of most DIY 4wders (and some workshops) is a worry. For it to be safe, it needs to be bolted down so it doesn't become a missile in a crash and it needs the best possible short circuit protection. A high rate of discharge or a short can cause an AGM to explode.

95% of DIYers don't realise how easy it is to short circuit a battery. Hpw many fit a fuse or fusible link (matched to the capacity of the wiring) at the pos terminal of every battery in their vehicle/trailer? Then how many cover and protect the pos terminal itself? Lots of things can short out on an exposed pos terminal and melt a battery - everything from a wrist watch to camping gear, or the battery moving.

I agree that I am more paranoid than most, but having seen a battery ignite and explode under the bonnet of a vehicle where the pos terminal was accidentally shorted by the bonnet coming down on it, is one thing that makes me more wary.

Hi phil and not sure where you got the info from but Ca/Ca batteries are the best leap in battery technology in decades.

Ca/Ca are far more robust than any standard AGM and last considerably longer than conventional flooded wet cell batteries. Only the Optima would be better and thats at a much higher price, at around twice times the price of an equivalent Ca/Ca battery and this all makes these Ca/Ca batteries ideally suited for RV/4x4 use.

Furthermore, even with the low operating voltage of your Prado, you can fully charge any battery and while Ca/Ca batteries will not be fully charged by an alternator, it doesn’t mean they will never get them over 60 to 70% charged. The reality is that your alternator can charge a Ca/Ca battery upwards of 95 to 97% and this info is available on one of Exides web sites.

Add this to the fact Ca/Ca batteries charge quicker, gas less, self discharge slower and have a longer life span than standard FWC batteries yet cost the same or LESS, why wouldn’t you use them i a 4x4?

Gday Drivesafe,
Good to see you're still around!
I tailored my comments to Ando's original question, and he's supplied very detailed and thought out information which is refereshing!

I've assumed his Prado has the usual regulated voltage of 14.3 down to 13.4 with temp regulation; He wants it as a second battery under the bonnet; He's doing the Canning (ie corrugations galore) in a few months.

Regarding Ca-Ca batteries:
(1) The charging algorithm for most Ca/Ca batteries is a long way from that provided by his Prado's alternator, requiring a period of much higher voltage. (Charging Algorithms). My attempts to find detailed technical information on SuperCharge batteries has failed. If you have access to this, please pass it on - it shouldn't be a secret!
(2) Some brands of chargers (eg Redarc reference) have acknowledged the different charging requirements with the introduction of specific calcium algorithms on their chargers.
(3) Personal experience - (a lot of my travel is in deserts with groups of many vehicles). I can remember 5 batteries dying on corrugated roads over the past 7 years - 4 have been calcium (Delcor and Supercharge), and one was an Exide Gel. It could be just coincidence, but it suggests to me that these batteries don't tolerate corrugations and heat as well as an Extreme or Overlander.

As far as being 60/70/97% charged (My name is not Collyn:-)), if it were to be used as a cranking battery, then chances are it would stay fully charged if driven every day for a reasonable distance. But Ando's stated its a second battery being used for a fridge.

If he owned a Discovery, and was charging the batteries off 240V and sticking to the bitumen, my answer would have been different or more likely I wouldn't have commented :-)

Cheers
Phil

Phil and Drivesafe,

Thanks for the detailed responses.

Regards
Ando

Hi Phil, and ALL the info you refereed to, and based your reply on, relates to batteries being charged with some sort of battery charger, which are all constant CURRENT charging devices.

None of it is relevant to the Ando’s question, as he was asking about charging while driving, meaning using his alternator which means we are talking about constant VOLTAGE charging ( also known as TAPED charging ) which is totally different in the way a battery is charged.

Furthermore Ca/Ca batteries have now been around long enough and in large enough numbers to show they not only out perform conventional flooded wet cell batteries, both as cranking batteries and as auxiliary/house batteries and they have a number of characteristics that are better than most AGMs.

Plus in Ando’s case, as with a number of other makes, where his alternator runs at a lower operating voltage, whether it’s his cranking battery or his auxiliary/house battery(s), they will still be fully charged and there are plenty of people out there with these lower operating alternator voltages that can prove they are getting fully charged batteries while driving.

Ca/Ca batteries are the battery of the future but they are here now.

Gday Drivesafe,
I'm listening to what you're saying... maybe the Ca/Ca batteries have improved and I'm being a bit harst based on personal experience ...But in all honesty, I'd still be fitting a battery that is designed to take the corrugations. For me that is still a choice between the Extreme, Overlander and Optima because they have the runs on the board.

Cheers
Phil

Hi Phil and don’t get me wrong, I think Optimas are one of the best batteries available, BUT AT A HUGE PRICE,

Phil,

As far as I can determine the Exide Extremes only come in N70 size, but you mentioned they come in N50. I would be very interested in one if they do come in this size.

Ando

Ando,
Here is the list of available Exide batteries - they list a N50EX. Just need to enquire at a dealer I guess.

Looks like Century have dropped the N50 Overlander. Highest capacity you'll get in that size would be the Remco AGM - 80Ah for $319 from Whitworths.

Drivesafe,
Nothing huge about $292 for an Optima D34 from the place in Adelaide I quoted! But they are only 55Ah...but its very usable.

Hi Phil but thats $292 for 55 Ah with about a 10 year life span verses $165 for a Ca/Ca 105 Ah with a common 5+ year life span.

Say you would need two Ca/Ca batteries over the ten years and you would two Optima 55 Ah to last ten years to have the same capacity.

Thats $330 for the Ca/Ca verses $584 for the Optimas.

So the Ca/Ca works out about half the cost of the Optima for the same amount of capacity spread over ten years, and the cost of the Ca/Ca batteries are spread out over five years while the Optimas are an up front total cost.

Again, Optima batteries are better but AT A HUGE COST.

Ando,
That other link wasn't quite right.This one lists the N50EX.

Thanks for the link Phil. For some reason I could not see the N50 when I was looking.

Ando

PS, I wrote the original post under my wifes login, hence the different name here.

So after all that can I fit an AGM battery in the back of my Jackaroo? There is no space under the bonnet for a third battery. The two there already there are needed for cranking. I thought one of the reasons for an AGM battery was that in could be used in a confined space.

Kevin

Hi Kevin, first off, as it’s going the back of your Jackaroo, it’s not in a confined space.

You can fit any type of battery inside the cab but no matter what type you use, it MUST be housed in a plastic battery box, because ALL batteries, in certain circumstances will spew out electrolyte.

By putting a battery in a plastic battery box and securing the battery so it can not fly around in the event of an accident and you have the safest set up for an auxiliary battery, mounted insde a vehicle’s cab.