I'd rather not vent but......

G'day Fab-io

You could consider an Optima Yellow Top. Expensive but a bloody good battery. It's my understanding that they are effectively sealed (you can lay them on their side), hence no problem with venting.

By the way, how often do you let the person out of your centre top storage box? He looks a tad cramped.

I have an Outback draw system. The 50 litre Waeco occupies only two thirds of the firdge slide. I had a bracket made which bridges the back third of the slide and put a 145aHr Delco gel battery on it. After seven years it is still going strong and when tested 3 months ago it is down to a 135 aHr battery. Having no room under the bonnet is really a blessing because batteries do not like heat. I am away 3 to 4 months every year and other smaller side trips so it gets a good workout. Who knows how long it will last.

Talk to your battery supplier any sealed battery will be safe and legal
Any battery that needs topping up with water is not sealed and is dangerous inside your passenger area as it will release acidic fumes that is why they need venting to the outside they also have a corrosion issue in most states it is illegal unless its a sealed battery
Cheers Kev

Fabio,

Provided you use a gel or agm battery (the acid in these is captive), you should not need any battery box. Venting is not required by such batteries either, provided you don't damage the battery by using excessive charge current. The manufacturer's recommended maximum should not be exceeded.

I'm sure you aren't planning to, but for the benefit of anyone watching but not aware, you should NEVER mount a wet acid battery inside the vehicle (in a box or otherwise) - the acid is dangerous and if you accidentally turned the vehicle, and the battery, upside down you'd already have enough problems without being bathed in concentrated acid! Also, explosive hydrogen gas may be given off by a wet cell battery during charging.

Just a thought - if space is a problem maybe you could fit a couple of smaller batteries more easily. By connecting them in parallel (ie the positive terminals connected together and the negative terminals connected together) you could create the required storage with two half size, half capacity batteries. This would cost a bit more but give you flexibility.

Cheers

John

First and most important, it must be understood that There is no such thing as a totally sealed battery in the lead acid family that does not require ventilation...NONE.

If you want to argue this one, I can quote chapter and verse from documentation of just about every manufacturer....including Optima.

Lots of the manufacturers will make various claims of being totally sealed or operating in any position in their advertising material....Then you get into their application notes or the material safety and data sheets and you find the real truth.

There are one or two battery sellers that are nothing short of wreckless about their claims and recommendations about batteries, how sealed they are and where they can be safely housed.

ALL and I do mean ALL lead acid batteries WILL vent explosive gasses and corrosive fumes or mists under certain circumstances......top of the list of causes are over charging and high temperatures.

The originators of the GELL technology "Sonnenschein" ( now owned by Exide)warn very strongly on their web site about ventilating batteries..all batteries.

There is also the very real issue that batteries fail..and sometimes catastrophicly....releasing explosive fumes and corrosive material.

As for the arguments about certain vehicles that had batteries under the seats.....Landrover batteries may have been accessed under the seat but the battery was in fact under the vehicle not inside the pasenger compartment or enclosed.

This is typical of many vehicles.

VW beetles had the battery under the rear seat....the single most popular rust repair section for the beetle is the rear floor pan under the rear seat...um..where the battery is.
It was also not uncommon for people to jump or dump the bottoms heavily on the rear seat of beetles and the seat springs short on the battery terminals...causing as a minimum excitement at worst fire.

Oh yes there have been a number of vehicles with batteries inside the boot...but in the past many vehicles had the petrol tank in the boot seperated only by the rear seat from the passenger compartment.....very much not common practice these days.

I do realise that in many vehicles the alternatives are hard or impossible.

If you must fit a battery inside the vehicle, first ask yourself..." Am I feeling lucky"

Then be very sure that the battery you select represents the minimum risk.

Always mount batteries upright.

Make sure that it is very solidly restrained...serioulsy this is more often than not underestimated.

make sure you provide as much ventilation as you possibly can

make sure your charging system remains in good repair at all times and the voltage regulation is appropriate for the battery.

AND.

you check on the battery regularly, to ensure that it is in good condition.


I would also sugest that you replace that battery early instead of waiting for it to fail.

Serioulsy think about this.
I know this is information a great many do not want to here......but these are the facts.

cheers

There's a few enterprising individuals over on the ford ranger forums who have been taking out the rear under seat storage inserts and mounting little optimas on a slant in there - nil bad effects thus far. You could always run a breather out through the wheel arch if you were concerned?

No one has mentioned LiFePO4 batteries? I've been very impressed with what I've read about them during my research. I've read they are pretty expensive, light weight, can be discharged further than lead acid batteries without damage, are faster to recharge and they are fully sealed. It sounds great in theory. Does anyone have real life experience with them?

WBS

Check ARB or other accessory suppliers - I have seen a couple of different styles of fitting 2nd battery under the Pajero bonnet - Tight, yes, but doable.

G'luck - Phil

Well thank you to everyone for your feedback, ideas and other comments.
I've done a fair bit of asking around, reading and research and it was time to commit and stop procrastinating ...... plus, I believe this thread, like all other good ones needs to offer some sort of conclusion (it poops me when the OP's don't bother to offer feedback).

I've decided to go with the Optima Yellow top D31A. Although a bit larger in size than I would have liked (330 length - was aiming for 280-300mm max), the price, claimed features, warranty and popularity lead me to believe this was a sensible choice. I found one from a local supplier on ebay here in Adelaide for $335 which is $35 more than I wanted to spend (so no takeaway coffee for a week), but a lot cheaper than what I was quoted for the same battery from other places.

http://www.ebay.com.au/itm/321240589610?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649#ht_2664wt_1124

I spoke to some people in the know regarding this battery and the expulsion of gases and the common consensus was that the likelihood of gases been expelled under normal driving/charging conditions with a 100 amp alternator is pretty much zero, even at higher cabin temperatures eg: locked up car on a hot day sitting idle. The same could not be said if using a battery charger, especially a high amp unit.

So again....a huge thank you to everyone who contributed to this thread. I've learnt a bit and solved my crisis.
Happy Exploring all.
Fab.

At the risk of negating everything already posted on this thread, I have a dual battery system installed under the bonnet of my Pajero. It all fits fine.

Sorry, my bad. Had no idea there was such a difference within Pajeros. All the best with your deliberations. But since you've shown me yours, I'll show you mine!