2nd battery inside !

[makeitfit]

Hi guys of great knowledge
I'm about to install a 2nd battery but inboard. It's to help out with my inboard rear winch and power amps.
What sort of power relay do I need for the split charging side of things ?
Does the battery need a vent to the outside ? I hope not but if needs be .
The battery I have is an 85 AH jobbie that will just fit here.

 

[rayf3262]

Even though the battery appears to be a sealed type there will still be a vent somewhere. Hydrogen gas is pretty explosive and right next to a tank full of LPG......... I would definitely arrange for some form of ventilation.

As for the relay, for charging purposes ~30A should be fine.
BUT you need to ensure that when the rear winch is operated or any significant load is applied to the rear battery that it is isolated from the main starter battery.
This means that if the engine is running and the split charge arrangement is charging the rear battery it should be disconnected from the front, you dont want a winch trying to draw large amounts of current through the split charge wiring!

The other option is to uprate the relay and wiring from front to rear to be able to handle the load imposed by the winch.

 

[Lazy-Ferret]

With the currents you could be playing with there, I would get a Starter solenoid from an older car that has the Bendix style starter motors. You can pick them up new on Fleabay for about a tenner.

Again, because of the high currents of the winch, and then charging it, if it is not a sealed battery, then yes it does need to be vented outside, as the gasses are explosive, and sink into any hollows.

 

[makeitfit]

Thanks chaps. I'll make a compartment for it and floor vent. Any ideas for a vent that will offer some water ingress restriction but still let gas out ?
I'm thinking ping pong ball in a tube .
Anyway are there any idiots guide to wiring diagrams for this kind of set up ? I'm not good at following wiring diagrams but no idea how to design one .

 

[jims-terrano]

Could you make a box around it and have a rubber hose venting out high up somewhere?

 

[makeitfit]

Could you make a box around it and have a rubber hose venting out high up somewhere?

Box yes, vent hose I like Am I right thinking then that hydrogen gas is given off and as such is lighter than air and so can vent upwards ?

 

[solarman216]

you really do need to make sure the outer hose from the LPG tank is sealed and taken below the floor so any leakage is totally isolated from the nearby battery, as for charging said battery you will need very heavy cable to reduce volt drop from the alternator 25 mm minimum, but I would use 50 mm and a 500 amp switch, that way you can use the start battery to boost the winch one for a short while and if engine still running will charge both and supply max alternator output as well, Rick

 

[rayf3262]

I'll scrible something up for you over the weekend.
But the principle is that whenever the winch is operated it drops out the split charge. This saves having to run heavy gauge cable from front to rear and having mahoosive relay/contactor's.

 

[solarman216]

Box yes, vent hose I like Am I right thinking then that hydrogen gas is given off and as such is lighter than air and so can vent upwards ?

I would not bother with a box around the battery as this will only tend to contain the gas, let it breath and make sure your connections are good, Rick

 

[makeitfit]

All the LPG pipes are shrouded so any leaks are allowed out through the floor.

 

[makeitfit]

I would not bother with a box around the battery as this will only tend to contain the gas, let it breath and make sure your connections are good, Rick

That area is normally all boxed in anyway Rick. I have a plywood deck that goes over the whole lot like this.

 

[jims-terrano]

How about some kind of ducting with a fan high up blowing air down and across the battery to disperse any gasses.

Looking good Pete:clap

 

[solarman216]

That area is normally all boxed in anyway Rick. I have a plywood deck that goes over the whole lot like this.

Mmmmmm does mean the gasses could accumulate under the decking in which case I would box the battery in and run a vent pipe up and out, Rick

 

[makeitfit]

Mmmmmm does mean the gasses could accumulate under the decking in which case I would box the battery in and run a vent pipe up and out, Rick

I will do just that

 

[makeitfit]

How about some kind of ducting with a fan high up blowing air down and across the battery to disperse any gasses.

Looking good Pete:clap

I was just thinking of a remote fan but on suck :sly

 

[The Patrolman]

The old mini vans had the batteries in the cab behind the seats somewhere I recall.

When the alternator regulator fails it over charges the battery an it gives of an ackrid gas in the cab, but you soon know about it as it makes your eyes water.

good luck :thumb2

 

[jims-terrano]

Only problem with sucking the gases passed the motor is that motors produce sparks

 

[solarman216]

passive vent is fine, Rick

 

[makeitfit]

I'm going to use some neoprene air duct 51mm diam should do it. I'll take it under the deck and then up to the rear pillar air vent. Nissan put it there for me specially
That should be naturally sucked out while driving me thinks :thumbs
I love a planning session

 

[solarman216]

I'm going to use some neoprene air duct 51mm diam should do it. I'll take it under the deck and then up to the rear pillar air vent. Nissan put it there for me specially
That should be naturally sucked out while drimore ving me thinks :thumbs
I love a planning session

51 mm more than enough but it must go up hill all the way, no droops 22 mm is much more than enough and easier to run, Rick