Aux Battery Cabling

Certainly in the good old days batteries kept in containers in vehicles had venting to the outside - eg the battery in the engine bay of a Jag Xj12 was contained in a box but it had a 12v fan to provide ventilation.

Gav - as you would be aware the standard 101 battery box is basically sealed but has small flutes cut into its outside to provide ventilation.

I cannot really speak about more modern vehicles like the Defender but I assume there is a vent to the compartment somewhere.

However as discussed above older style lead acid batteries with the caps with vent holes in the caps could give off gas when being charged (my neighbour lost an eye when one blew up) but modern sealed batteries will produce gas when being charged however with a normal rate of charge this is reabsorbed into the fluid and does not vent to atmosphere but all bets are off if there is a problem when charging and the production of gas is too much to be reabsorbed and then it must vent to atmosphere - this is of course hydrogen.

On the thread topic of running cables to the rear - as I have not yet put in an aux battery system, I have a cable that I ran to the rear of my RRS from the main battery - tends to run along cables already on the chassis and in a couple of spots does run inside the chassis - I have already found one spot where a bit of chaffing has occurred from normal driving vibration and thanks to comments about course welds inside the chassis I might have a rethink about the inside the chassis bit.

Cheers

Garry

I don't think there is anything to worry about with a Optima battery


However just for accuracy's sake I would like to point out to all protagonists that VWs which had the battery under the seat had a European battery with a vent hose which went to the outside of the car.


Ditto with my BMW E36 M3 which had the battery in the boot. It had a large Varta with a vent hose to the outside. So fumes were considered by European manufacturers with just normal flooded batteries when they placed batteries inside the car.
Regards Philip A

Hi Garry and why are you putting the cabling in the chassis in the first place.

The D3, D4 and RRS are without question, the easiest vehicles to run cabling inside the cab, with the existing wire looms.

Furthermore, if you run the cabling through the chassis and they have to work on the motor, they undo a few bolts and lift the body off the chassis, cutting the cables.

BTW, the Jag had a fan because it was a totally sealed compartment and they had no choice.

As to that “document”, it has been written by a journalist, not a scientist or engineer. There are too many errors in it.

The most obvious is that they imply water vapour is dangerous. They obviously thing Hydrogen and Oxygen “GAS” has nothing to do with water “VAPOUR”

There are a number of other errors as well but the point our “expert” can get through his head is that the POTENTIAL danger of having a battery gas while in a cab only occur if something goes wrong.

The two most common causes of gassing of battery in a cab, and the document mentions these, is if a battery charger continues to raise the voltage being applied to a battery, which will cause Thermal Runaway ( something Ctek chargers are renowned for ) or if a cell collapses and causes an internal short inside the battery.

The problem for the “expert” is that it does not matter if you are using the cheapest cranking battery you get or the dearest AGM, they will both suffer the same fate.

Quote:

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Originally Posted by PhilipA

However just for accuracy's sake I would like to point out to all protagonists that VWs which had the battery under the seat had a European battery with a vent hose which went to the outside of the car

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Hi Philip and that would have only been the last of the run because they did not have any venting at all for most of them.

Furthermore, have a look at VE Commodore, which had it’s craning battery located in the boot, which is NOT sealed from the cab.

The first of the VE had a cover and a little hose that ran down through the floor.

But not long into the run, they did away with the hose and the battery just vented into the boot or cab, if it had to vent.

As posted earlier in this thread, there are plenty of NEW makes of vehicles with their cranking battery in or near the cab.

Dave,

Discovery 2 with 120AH Fullriver AGM fitted in the RH rear bin.

Traxide USI 160 with 3 B/S cable (+ & - ) running to both batteries.

Cables to rear run along the top of the RH chassis rail in conduit - cable tied every 350mm or so. Entry into rear quarter space through the vent inside the panel.

Dave

Quote:

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Originally Posted by drivesafe

Hi Garry and why are you putting the cabling in the chassis in the first place.

The D3, D4 and RRS are without question, the easiest vehicles to run cabling inside the cab, with the existing wire looms.

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I was following a loom that went into the chassis so I just followed and came out where the loom came out.

I went that way underneath as it was relatively easy - most runs on top of the chassis nice and safe and I did not want to pull stuff out from the inside and I did not have to find a way into the cabin - just picked up a loom in the front passenger wheel well and followed it all the way to the back - no lifting carpet, no punching holes in grommets in the firewall and no pulling internal panels off and breaking fasteners.

Cheers

Garry

Quote:

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Originally Posted by PhilipA

However just for accuracy's sake I would like to point out to all protagonists that VWs which had the battery under the seat had a European battery with a vent hose which went to the outside of the car.

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They might have left the factory that way but all the ones I worked on wouldn't have had the original battery, especially the one that blew up in my face when removing a battery charger.

Quote:

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Originally Posted by d2dave

They might have left the factory that way but all the ones I worked on wouldn't have had the original battery, especially the one that blew up in my face when removing a battery charger.

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And there be the REAL threat.

All care should be taken when working on any battery, BUT this still does no guaranty they won’t spray electrolyte or, as in Dave’s case, explode.

Philip, I have never seen a Beetle with a vent hose fitted but as I posted, the last of the run may well have had them. Most of the ones I’ve had anything to do with, were all old Beetles

Philip, I have never seen a Beetle with a vent hose fitted but as I posted, the last of the run may well have had them. Most of the ones I’ve had anything to do with, were all old Beetles


Drivesafe, in the old days Din batteries were hard to get and most people just replaced the OEM with Australian 6 volt batteries which were not vented. I am sure that they came from the factory with a vented Din battery as P76 has shown in the photo. I had a Variant Square back 12 volt and it had a vented battery also.


People in those days did lots of dangerous things like leaving the cover off the battery under the seat which in one I rented shorted the +and - across the seat springs , giving my wife quite a warm bottom, and causing a dash to the surf to put the fire out.
Regards Philip A

Quote:

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Originally Posted by PhilipA

I am sure that they came from the factory with a vented Din battery as P76 has shown in the photo. I had a Variant Square back 12 volt and it had a vented battery also.

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That's not a vented battery, it's just the positive battery cable and a tin cover. I worked on loads of 60s Beetles in my youth and none of them had provision for a vent.

Also Minis from the 60s had regular non vented batteries inside the boot.