Hi,

 

Would like to use my car to charge phones, laptops, tablets etc, and perhaps run a 12v fridge for travels.

 

Worried this will nuke the main battery however, does anyone have experience of installing a secondary battery on a Mk3 Superb, and getting it to charge from the alternator, etc?

 

Thanks.

Haven't installed on a superb but have done on a Bongo so if you want some general info I can help you out?

Would be very interested. Considering a driving tour of Europe next summer and keeping fridge in the boot would be harsh on main batter I fear

It might well be. Advantage to a secondary/leisure battery is that it can run your fridge while the car is off as well with no fears of draining the drive battery.

To fit it in the bongo I got a smart/split relay. This basically detects the voltage going to the drive battery and when there's enough in it it will spill over and charge the leisure battery.

The slightly more complicated bit is taking the power from the leisure battery rather than the drive battery. In the bongo this was simply a case of running a wire from the leisure battery to the correct fuses (stereo etc) and I'd imagine would be the same in any vehicle.

So in short you need a place to mount the leisure battery. A smart split charging relay. A deep cycle battery. And a little wiring to run what you need.

Just moved this to a place where it might get a better response as isn't a Superb Project thread.

I solved a similar issue in 2 steps:

 

1. Installed a larger (and better technology) AGM Battery 096AGM (70ah 760amps)

 

2. Bought the item below for charging my devices, jump starting the car etc. At any time I can charge it from the car battery and it can supply both 12v and 19v (for laptops)

 

http://www.antigravitybatteries-uk.co.uk/microstart-jump-starter/micro-start-xp-10.html

I installed a split charge relay behind the boot lining in my Superb II in order to make the 12 V socket in the boot into an ignition switched socket so I can run a fridge and inverter from this while driving without needing to remember to shut everything off when I stop. Putting a battery into the side compartment in the boot with a split charge circuit and running power from this to the 12 V socket in the boot wall would give you a power source that doesn't depend on the main battery without taking up any obvious room in the car and without having to run new wires since you can just use the 180 W supply (It's got a 15 A fuse on the Superb II anyway) to the boot socket already. You will have to do some careful measuring to make sure the battery you choose will fit in the side compartment though as I suspect it will be a bit tight.

 

The other thing I'm not sure about is whether the smart charging system will have problems with a dual battery setup. If you change to a battery with a different capacity to the OEM one you are supposed to tell the ECU the new battery capacity as the car stops charging to save fuel once it reckons the battery is full. It may not have a setting to deal with doubling the battery capacity.

I did a similar thing on my Disco - although no smart charge on that. I used a T Maxx split charge system, which includes a battery monitor and all the cables, so simplified things a lot. This worked by having a live connection on the main battery, via the control solenoid to the secondary battery. This only allowed the second battery to charge when the voltage reached 12.5v on the main. I used a normal leisure battery as the reserve, which was mounted under the bonnet.

In a car, I would advise getting a sealed battery, something like an Optima spiral wound gel battery, as these can be mounted at any angle without leaks, so you wouldn't really need to worry about encasing the battery, just securing it to the car. From the second battery you would need a chunky power cable, feeding a secondary fuse board to spur off.

Plenty of stuff on www.vehiclewiringproducts.co.uk for split charge. You can use a relay to do the job, I used the T maxx setup purely as it was a complete kit with the monitor for both batteries.

I solved a similar issue in 2 steps:

 

1. Installed a larger (and better technology) AGM Battery 096AGM (70ah 760amps)

 

2. Bought the item below for charging my devices, jump starting the car etc. At any time I can charge it from the car battery and it can supply both 12v and 19v (for laptops)

 

http://www.antigravitybatteries-uk.co.uk/microstart-jump-starter/micro-start-xp-10.html

 

I would also suggest a solution like this. Nice and simple and not linked to the car..