I have been looking into this and seen a couple of threads on here about people who have done these and looking for some feedback. This is not something I could make myself so looking at available kits to buy and then fit myself.

Have found two and was looking for some feedback or if anyone has used either?

https://www.luxurylandroverupgrades.com/pr...attery-kit

Or

http://www.traxide.com.au/diy-dual-battery...t90-s.html

I want to be able to run something in the boot from the 12v socket and not worry about the car not starting again if I tan a fridge for example and left the car with it running. Also would like to be able to leave the ignition on to be able to watch tv/dvd whilst stationary without worrying about not starting again

Cheers Alex

2018 Skoda Kodiaq vRS
2009 Caterham Supersport Race car
2007 M5 Touring
2005 Range Rover Vogue SE Supercharged
2004 SL55 AMG

They look like they work differently - so one or the other may be better for what you want.....

The first is a straight relay - looks like it's switched by fitting a fuse to the switched live - so that whenever the ignition is on, the batteries are connected together - whenever the ignition is off they are disconnected. If you sit there with the ignition on, then you could still potentially flatten both batteries, though it would clearly take a lot longer.....

The second looks like it has a voltage sensitive relay - so as soon as the voltage goes above a certain level, the batteries connect - that usually means that they will only connect when the alternator is running. The question with that one is how to force them together to start if the main battery is flat - not clear if there's an override manual switch....

The second one looks like it's designed to operate independently - the fridge or other accessory runs off the second battery and that's it's primary use. It can run until flat and have no impact on the main battery which carries on as normal.

The first could be run in the same mode, but if the fridge flattens the second battery - you then put an extra load on the main battery right as you're trying to start the car as you immediately connect the batteries together with the ignition. Likely OK as long as the main battery is fully charged and you start the car straight away.
Alternatively it could be run with accessories on the main battery - then use the second purely to boost starting, but you'd need to make sure the cables were up to a full starting load.....

Thanks for that.

Not wanting to sound daft, but would the batteries both have to be the same type with the first option? Or could I use a deep cycle/leisure battery that would last longer?

Thanks Alex

2018 Skoda Kodiaq vRS
2009 Caterham Supersport Race car
2007 M5 Touring
2005 Range Rover Vogue SE Supercharged
2004 SL55 AMG

Both options connect the 2 batteries together - just use a different trigger. The first option means they could be connected together when not being charged - not sure if that's a problem with different batteries or not - should be fine. but I'm far from expert - maybe a question for the vendor ?

Most dual setups would have a starter battery & a deep cycle battery.

I do know that leaving them permanently connected together - even matched batteries - is a bad idea as they flatten each other over time - but not sure how quickly that occurs......

Dan_uk_1984 did this on his (now mine). Look him up on here and read his posts on it.

Second battery fits in the removable tow hook space in the boot and worked great. However beware it can start to drain the main battery when older and on its way out. This could lead to a complete shutdown whilst driving and loss of everything, engine, lights, power steering etc. (Ask me how I know!! )

" I do know that leaving them permanently connected together - even matched batteries - is a bad idea as they flatten each other over time - but not sure how quickly that occurs......"

Just as a reassurance I've had to similar batteries connected together permanently for years without any trouble whatsoever.

@Dolphinboy what battery is fitted in the back of your car as trying to sort that out now.

Thanks Alex

2018 Skoda Kodiaq vRS
2009 Caterham Supersport Race car
2007 M5 Touring
2005 Range Rover Vogue SE Supercharged
2004 SL55 AMG

its a smaller one. will go and get a pic when the rain has stopped

@alstair & Joe90

Mine was done in 2009/10 and I had the "power-out" in 2016.

I was interested in this bit of kit (the luxury one) and he has an install video where he explained that you can have two different batteries AGM or otherwise and they don't need to be the same size.

Also he concurs with the issue some have mentioned on here that connecting two batteries together is a bad idea as each one tries to charge the other and eventually flatten each other over a few days his design apparently does not allow this to happen.

the only thing that has stopped me so far is that I would like to hide the second battery somewhere maybe dolphinboy's picture will help with my decision

Maccaa Current FF Westminster 4.4 V8

In solar systems I fit, it’s common to join many multiple batteries with out issue, just charge each one to the same star of charge. Only issue you get is if one starts to fail it will pull all the other batteries down but this is rare on well maintained systems.

@Maccaa I have ordered the luxury one and will fit the smaller battery in the right hand bin where the tow bar would sit so I have to find a new space for that instead.

Dolphin boy is going to kindly give me details of the battery he has fitted to his so I can start searching for a battery to get.

Cheers Alex

2018 Skoda Kodiaq vRS
2009 Caterham Supersport Race car
2007 M5 Touring
2005 Range Rover Vogue SE Supercharged
2004 SL55 AMG

zarnd thanks I will probably do the same once Dolphinboy has posted a pic...no pressure  Current FF Westminster 4.4 V8

As I said to the guy selling the luxury relay kit online - £65 for a relay and a few wires? He's having a laugh.
If you fit a second battery that isn't at least similar to the one up front you're wasting your time completely. His video also shows the 'professional fitting' using a bloody ratchet strap.

The Traxide kit on the other hand looks to be a proper split charger system which is designed for the car in a usable location. You can fit whatever second battery you happen to have to hand that goes in the hole and has an indication of the charge level too.

You pays your money...

Quote:

His video also shows the 'professional fitting' using a bloody ratchet strap.

I wouldent call that luxury (is he serious) kit a dual battery charging / isolator kit in a pink fit .. And wow it is advertised as a way to fix fault codes showing up....

As the poster above said your paying stupid prices for $15 worth of parts he has put together and heat shrinked



Dave 2010 3.6TDV8 Autobiography
Bas remap, Egr deleted (blanked & via remap) , Cold air intake, Turbo back exhaust, Provent 200 catch can, Banks idash gauge, 275/55/R20

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Past - 02 & 03 TD6 And an 1984 Classic