Duel battery set up

[elty001]

I've yet to start this mod.
Something else always seems to get in the way and use any spare cash I have.

 

[jims-terrano]

I fitted a second battery but never got around to the starter solenoid part but it’s a dam fine idea. I wouldn’t just use second battery for a just in case my main battery is flat. Get a feed to a fuse box in the boot and use the power when you are out and about. Mine runs some rear Work lights on the roof, an interior light and sockets for chargers or cool box.

 

[bbbmmm55]

Ive collected most of the bits I need for this except the fuse boxes. Stealing the ideas from lazy ferret, jim and rustic. Im going to fit fuse box back and front for any future extras.

What im unsure of is cable diameter to use. I got hold of some 25mm2 for the solenoid to directly connect the 2 batteries.

For running between the batteries and relay the running power to the back of the car should I be using 10mm2 or will 6mm2 do the job?

 

[kitchenman]

Thanks for the mention above
I fitted a second alt, as you had air con you already have the fixings and the adjuster
Bit of a job to get at and the alt needs to be further forward than the aircon pump
Mine never had air con I bought it all in bits and pieces before doing it, been running well for a couple of years

I have pictures somewhere

 

[solarman216]

Ive collected most of the bits I need for this except the fuse boxes. Stealing the ideas from lazy ferret, jim and rustic. Im going to fit fuse box back and front for any future extras.

What im unsure of is cable diameter to use. I got hold of some 25mm2 for the solenoid to directly connect the 2 batteries.

For running between the batteries and relay the running power to the back of the car should I be using 10mm2 or will 6mm2 do the job?

Between the batteries you should be using 50mm2 if you are thinking of using the second battery to start if first battery is flat, as fo 2nd battery to rear this will largely depend on what you want to run from it, if for instance it is a rear winch then 50mm2 as a minimum, if it is a fridge box 10mm2 will probably be OK remember this type of device is voltage sensitive so if it demands 12.5 volts and you only give it 12 it will not work so well, so with the device connected measure the volt drop at the device, Rick

 

[Lazy-Ferret]

As Rick says, the main problem is the volt drop over the length of the cable run, on Suz's car, it worked out at 7metres from the 2nd battery in the front, to the distribution box in the rear.

If you use the form half way down this page, you can try different cable sizes and current draws, to see what impact different cables have.

On Suz's car I ran 70mm2 as I got 10metres end of roll, cheap. Her wiring is fantastic, there is no volt drop at all, and even at the caravan fridge, we are seeing 13.2volts when the engine is running, so it runs a dream. On mine, I ran 3 separate 12mm2 wires, originally each having a separate task, but in the end I paralleled them up, and I can still only get 11.5 volts at the caravan fridge with the engine running.

Basically, it truly is a case for the girls to decide... "Bigger is better" :lol

 

[bbbmmm55]

Between the batteries you should be using 50mm2 if you are thinking of using the second battery to start if first battery is flat, as fo 2nd battery to rear this will largely depend on what you want to run from it, if for instance it is a rear winch then 50mm2 as a minimum, if it is a fridge box 10mm2 will probably be OK remember this type of device is voltage sensitive so if it demands 12.5 volts and you only give it 12 it will not work so well, so with the device connected measure the volt drop at the device, Rick

Thanks Rick. Guess im back to the drawing board for the time being. I have enough cable for some lengths in parrallel but will hunt for some affordable properly sized cable and determine what kind of loading is likely.

 

[bbbmmm55]

As Rick says, the main problem is the volt drop over the length of the cable run, on Suz's car, it worked out at 7metres from the 2nd battery in the front, to the distribution box in the rear.

If you use the form half way down this page, you can try different cable sizes and current draws, to see what impact different cables have.

On Suz's car I ran 70mm2 as I got 10metres end of roll, cheap. Her wiring is fantastic, there is no volt drop at all, and even at the caravan fridge, we are seeing 13.2volts when the engine is running, so it runs a dream. On mine, I ran 3 separate 12mm2 wires, originally each having a separate task, but in the end I paralleled them up, and I can still only get 11.5 volts at the caravan fridge with the engine running.

Basically, it truly is a case for the girls to decide... "Bigger is better" :lol

:lol

I will have a good measure up and use that calculator to crunch the numbers. When running the cables in parrallel is the main issue getting the connectikns into the fittings or would i be subject to increased losses?

 

[Lazy-Ferret]

[emoji38]

I will have a good measure up and use that calculator to crunch the numbers. When running the cables in parrallel is the main issue getting the connectikns into the fittings or would i be subject to increased losses?

In theory... separate parallel cables should be better as more heat dissipation, so less loss, but because of all the extra insulation it takes up more physical room, so you could have run a bigger conductor in the first place, which would also mean less heat is generated... you get the idea

As you say, more cables are harder to terminate neatly, but if you have access to smaller cable more easily as I did at the time, its a good option.

Sent from my SM-G930F using Tapatalk