Twin Battery Question

[jabber62]

I have a MK7 2012 high roof mwb which I am slowly converting. I am told there are two batteries under the drivers seat, one for starting the van and the other for everything else. I am wondering rather than put in a third leisure battery, is it doable to replace the batteries under the seat with a heavy duty one for all things van and a leisure battery for all things camper. Is the space adequte for that set up. (would the batteries be physically bigger) Sorry if this is a stupid question but when it comes to auto electrics...guilty as charged

[dumper]

You’d be better off with separate leisure batteries indpendant of van batteries and a B2B charger system if the front aux battery goes flat or voltage low it will cause all sorts problems with the van systems

[hectors-tranny]

Yep - defo as Dumper says.

[jabber62]

Thanks guys..much appreciated.

[Noctule]

On the back of the seat you will find three power points to connect any accessories to. If your van is Euro4 attach a voltage sensing relay to switch a decent relay to charge the leisure batteries. If it's Euro5 you need to fit a B2B charger as above. If you have the money to spare then a B2B charger is the better option, especially if you have several larger batteries to charge as it will charge them at 14.4v regardless of the system voltage.

Mat

[hectors-tranny]

Defo a B2B charger is the way to go. Charges leisure battery very fast. I'm pretty sure all Mk8s have smart alternators so can't be used with VSRs anyway.

[vanali]

Hi, I've been working on converting my Mk7 2013 fitted with dual factory fitted batteries. I switched to a single passenger seat and fitted 2 x 110ah low height batteries under the passenger seat. I linked them to one of the 60amp fused outputs under the red cover on the drivers seat base through a voltage sensitive relay (opens to charge the "leisure batteries" at 13.3v and closes at 12.6v) which should prevent running down either of the factory fitted batteries if I understand correctly. The 2 x 110ah batteries supply the 12v leisure circuit and 12v fridge. I'm now wondering if I should have gone for a B2B set-up

[Outtheway]

On the back of the seat you will find three power points to connect any accessories to. If your van is Euro4 attach a voltage sensing relay to switch a decent relay to charge the leisure batteries. If it's Euro5 you need to fit a B2B charger as above. If you have the money to spare then a B2B charger is the better option, especially if you have several larger batteries to charge as it will charge them at 14.4v regardless of the system voltage.

Mat

How can I tell if it's a Euro4 or Euro5? New to transits, mine is a 2010 crewvan

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[Cider Andy]

On the back of the seat you will find three power points to connect any accessories to. If your van is Euro4 attach a voltage sensing relay to switch a decent relay to charge the leisure batteries. If it's Euro5 you need to fit a B2B charger as above. If you have the money to spare then a B2B charger is the better option, especially if you have several larger batteries to charge as it will charge them at 14.4v regardless of the system voltage.

Mat

How can I tell if it's a Euro4 or Euro5? New to transits, mine is a 2010 crewvan.

2010 is a Euro4 van. It too has a smart alternator but the split-charging setup does work with a voltage sensing relay - I've fitted one on my own van.

As someone else suggested, I'd replace the twin passenger seat with a single seat sitting on the same box as the driver's seat. It bolts straight in to the same mounting holes and will accomodate a pair of 110Ah leisure batteries. However, single passenger seats with a right-hand armrest and height adjustment are quite rare and command a premium. Another option is to search for a driver's seat on eBay Germany (search for "Transit sitz"). I got lucky with the single passenger seat as I found one out of a Tourneo, complete with the box base, for £10! The fabric upholstery is wrong but as I'm reupholstering the seats it's not an issue.

If you want to keep the twin passenger seat, not all vans come with two batteries from the factory so it can certainly be converted to a single battery setup using the same under-seat fusebox but it has a bus bar in place of the twin battery relay. The thing is, I don't know if any other wiring needs changing and I think the BCM has to be reprogrammed as well.

[Cider Andy]

2010 is a Euro4 van. It too has a smart alternator but the split-charging setup does work with a voltage sensing relay - I've fitted one on my own van.

There's a bit of confusion about what a 'smart' alternator is. For the last 15 or 20 years a 'smart' alternator has been around, smart because after starting the engine it gently raises the output voltage irrespective of engine speed to prevent damage to electronic equipment. But a 'smart' alternator these days, introduced to help meet Euro6 emissions standards, forms part of the regenerative braking systems, in conjuntion with on-board ECUs and different battery technologies. It's these vehicles that need battery-to battery charging systems to totally separate the modern vehicle electrical system from the traditional 'leisure' electrical systems.

Whilst you don't need such a BtoB charging system on older vehicles, there is still a benefit in using one over a VSR split charger as it will charge the leisure batteries more quickly and to a higher state.

[lcbandit]

How can you tell if you have a smart alternator? I have a lwb 2013 transit ex network rail and trying to sort alternative charging out for my 2 leisure batteries

[hectors-tranny]

I wouldn’t worry about it - just get a B2B charger.

Apart for the advantages listed above, your leisure batteries will also last much longer, as the charger keeps them healthy.

Brilliant bit of kit.