Outer Limits 4x4 Board

I know AGM batteries can be stored/used in the cabin of the car but can Sealed Maintenance Free batteries be used also?

I do seem to recall my parents BMW having a battery under the back seat and I guess they were Sealed Maintenance Free batteries but what I'm looking for is a hybrid (cranking and deep cycle) battery.

I currently use a Supercharge Allrounder, which is a hybrid, as my main battery and would like to use another one in a battery box in the cabin. Whitworths Marine describes it as Sealed Maintenance Free batteries but Supercharge don't say it's sealed. I'll have to check with Supercharge to make sure.

I like marine batteries as they tend to be hybrid construction but I can't find many that are sealed.

The main reason I'm not going with an AGM is the huge coin they cost and looking for an alternative.

Cheers.

I think the devil will be in the interpretation of the 'style' of the battery. Some battery manufacturers call their units, sealed, low maintenance or sealed no maintenance, and its a battery that stops you topping it up, but it still has a very small venting system for any gassing activity.
The unit in the BMW is likely to be a gel unit, which is totally sealed and can even be mounted upside down.
I am in two minds about doing this. I cannot see a massive corrosion issue with any venting, but I can't comment about the gassing and any explosive condition that may occur. You obviously need an ignition source also to set it off.
Sounds straight forward, but a couple of risks perhaps. I have vented batteries within the cabin, but the vent tubes are actually piped up and vent outisde the cabin area.

a maintenance free battery still has a vent to atmosphere, the bmw you speek of will have a din battery with a vent tube running out of the car. so the answer is it is not advised or legal to do so as gasses will vent in the cabin

Hi TheOtherLeft, all batteries have vents and ALL batteries can and are mounted inside the cab of vehicle.

While many people will mount AGMs inside a vehicle without putting it in a battery box, they still risk having corrosive gel being forced out of the battery if it’s overcharged.

Flooded wet cell batteries can be mounted inside the cab and many new vehicles come with cranking batteries mounted inside the cab.

Vehicles like VW Kombis and Fiat trucks are used by many of the Motor home makers and these have their cranking battery mounted in the cab and then the is new Commodores. Their cranking battery is mounted in the boot and the boot is not sealed from the passenger cabin, in fact the center of the rear seat folds down to give access to the boot.

Next, you will not get a gas build-up that will be sufficiently strong enough to blow the vehicle up, this is one of the many internet myths.

Furthermore, if you have a normal flooded wet cell battery mounted in the cab and you overcharge it, it will stink but you can simply top up the water. BUT if you have a sealed battery, not only will it over change at a lower voltage than a flooded wet cell battery will, if you smell it, it's already too late, the battery will be stuffed.

In reality, through the grace of having a long cable run to connect a battery mounted in the cab of a vehicle to the cranking battery in the engine bay, it is extremely unlikely that you will ever overcharge any battery mounted in the cab of a vehicle because the long cable run acts as a form of regulator, protecting the battery.

So TheOtherLeft, you can fit what ever battery you want in the cab of a vehicle, just make sure you mount it in a battery box.

drivesafe wrote:
So TheOtherLeft, you can fit what ever battery you want in the cab of a vehicle, just make sure you mount it in a battery box.

What are the legalities of doing this? Also, if the vehicle should roll over there could be other implications if a "wet cell" is in the passenger area.

Edit just found this with advice from an engineer http://www.3rdrock4x4.com/forum/viewtop ... w=previous

Hi murcod, there are no laws or ADRs governing the use or type of battery used in the cab of a vehicle.

As to venting, this should be done but not to get gasses out of the cabin, it’s done to stop any form of pressure building up in the battery box itself and if you have a look at any commercially manufactured battery box, they a usually full of holes, for this very reason.

I use Optima batteries in the cabin of my truck, and they are mounted in special CNC'd Billet cages plus a special 25x50 RHS saftey bar across the top in case of a rollover........safety is paramount in the cab.........trust me, I have had a few really violent rolls , and nothing stays put unless it is really well bolted down, and I wouldn't have a wet cell battery in the cabin for the love of money, legal or not.

I wouldn't relish the thought of hanging upside down trapped in a rolled vehicle while battery acid dripped slowly over me. So the only way I'd have one under a seat or the like would be an Optima or other Gel type.
But a normal battery in some kind of battery box, secured solidly to the vehicle might be ok, and if you're really worried about venting, you could put some kind of breather tube on the box to the outside, and seal the rest of the box up so that it can only vent to the outside through the breather.
But then I'm sure no battery expert, so that's just my 5 cents worth (couldn't give you 2 cents worth, there aren't any 1 and 2 cent coins around, so keep the change).

I've seen a couple of different style battery boxes (from normal auto type outlets) and none are even close to being "water tight".

Are air/ water tight boxes available that could be vented to atmosphere?