Adding a 2nd Leisure Battery to a Beach

[gareth230380]

I'm looking to put a 2nd leisure battery in my Beach under the drivers seat. My current battery is 7 years old and so am going to purchase 2 batteries at the same time so they are matched.

The question I have is relating to the load and earth when fixing in parallel.

I've looked at the wiring diagrams for the 2014 Beach/SE and it shows the load and earth all comes from the Primary battery under the Seat with the Secondary battery in the back having direct links to and from it (with a fuse on the +).

This is really easy to do and I was going to copy until I read more. My understanding is this will create a voltage drop between the two with the primary battery working harder but also the secondary battery would not then charge fully.

The way to create a balanced system is to connect them the same but to take the load from battery A and the earth from battery B. This would mean removing the earth on my passenger seat battery and adding the earth to the new battery under the drivers seat.

Am I getting overly worried and not need to do this as surely VW would have done it this way if it was so crucial?

Does anyone have a monitor on each of their batteries and see an imbalance?

 

[WelshGas]

I'm looking to put a 2nd leisure battery in my Beach under the drivers seat. My current battery is 7 years old and so am going to purchase 2 batteries at the same time so they are matched.

The question I have is relating to the load and earth when fixing in parallel.

I've looked at the wiring diagrams for the 2014 Beach/SE and it shows the load and earth all comes from the Primary battery under the Seat with the Secondary battery in the back having direct links to and from it (with a fuse on the +).

This is really easy to do and I was going to copy until I read more. My understanding is this will create a voltage drop between the two with the primary battery working harder but also the secondary battery would not then charge fully.

The way to create a balanced system is to connect them the same but to take the load from battery A and the earth from battery B. This would mean removing the earth on my passenger seat battery and adding the earth to the new battery under the drivers seat.

Am I getting overly worried and not need to do this as surely VW would have done it this way if it was so crucial?

Does anyone have a monitor on each of their batteries and see an imbalance?

This is how VW wire the 2 Leisure Batteries on the SE/Ocean.
There is also a 50 amp, upgraded on the T6 to 75 amp I believe, Cube fuse on the +tve pole of the 2nd battery.

 

[Tarquers]

So when on hook up your 240 socket inside runs off the invertor? Seems a bit of a waste, or is it VW being economical with the drawing? The positive terminals are at the same voltage as they are connected to the same supply point. The earth is also common as both negative terminals are connected together. You may get a bit of a drop down the cable between the batteries under the seats, but probably not enough to measure.

Used to use a series/parallel setup on tanks with 24v, with 10 batteries in, we used to rotate the batteries around to maintain even charge and discharge but never really worked out the physics of it. As in theory it is all one big battery. Same here? Call an expert in at this point!

 

[gareth230380]

This is the wiring diagram showing earth and loads going from a single battery and different to the one you’ve posted? Really confused now. May get an auto electrician to sort.

 

[Tarquers]

if you leave the earth where it is, you can take the supply side across to the new (third battery) like this:

 

[WelshGas]

So when on hook up your 240 socket inside runs off the invertor? Seems a bit of a waste, or is it VW being economical with the drawing? The positive terminals are at the same voltage as they are connected to the same supply point. The earth is also common as both negative terminals are connected together. You may get a bit of a drop down the cable between the batteries under the seats, but probably not enough to measure.

Used to use a series/parallel setup on tanks with 24v, with 10 batteries in, we used to rotate the batteries around to maintain even charge and discharge but never really worked out the physics of it. As in theory it is all one big battery. Same here? Call an expert in at this point!

Incorrect.
there is a Mains 230v socket on the mains circuit.
There is a 150 w, now 300 w On the T6.1, Inverter that runs off the Leisure Batteries.

The 230v EHU mains circuit isn’t shown on that circuit diagram.

 

[WelshGas]

This is the wiring diagram showing earth and loads going from a single battery and different to the one you’ve posted? Really confused now. May get an auto electrician to sort.

View attachment 74531

The Diagram is from this VW publication

 

[gareth230380]

the 2008 wiring diagram (see attached) does as per your document, guessing they changed it in the T5.1

 

[Tarquers]

Incorrect.
there is a Mains 230v socket on the mains circuit.
There is a 150 w, now 300 w On the T6.1, Inverter that runs off the Leisure Batteries.

The 230v EHU mains circuit isn’t shown on that circuit diagram.

My comment based on your diagram, garbage in, garbage out. Regardless of source of diagram, if it’s wrong it doesn’t help when offered as a source.

 

[WelshGas]

My comment based on your diagram, garbage in, garbage out. Regardless of source of diagram, if it’s wrong it doesn’t help when offered as a source.

That is the 12v Leisure Circuit with the 12v Inverter Nothing to do with the 230 v EHU circuit.
If you want further explanation to understand it I would refer to the VW document in Post 7.
Unlike some, I am prepared to offer some information . If you Disagree with VW then that’s your prerogative and I suggest you take it up with VW oh mighty one.

 

[Caliconfidential]

Did you ever finish this job and how is 2 leisure batteries in a beach? I am currently thinking solar over a second battery..

 

[Leopold_Stuff]

Did you ever finish this job and how is 2 leisure batteries in a beach? I am currently thinking solar over a second battery..

Yup, same question here. I would like to connect 2nd leisure battery in my T6.1 Beach and im not sure how to make it. Any ideas? :/

 

[Ch1pbutty]

Did you ever finish this job and how is 2 leisure batteries in a beach? I am currently thinking solar over a second battery..

Solar would be a better option

If you fitted a 2nd battery, you would still need to charge it somehow…so you are not really solving the problem. Whereas solar will continue to top the battery up when parked / camping.

 

[mike2060]

Having just one batt and even solar would not work for charging eMTBs. Correct me if I'm wrong but a full power eMTB with 650wh battery could be charged ~1 times from the standard battery.

One other, no-tools solution, is to buy external power station like ecoflow or clones and permanently have it plugged in the 12V socket. Then charge the ebikes off of that. Not sure what control unit would show.

I would also like to put second leisure battery under the passenger seat in my Beach because of the empty space there. But I am not skilled enough to do it. External power station probably wont fit there and even if you wont be able to remove it later.

 

[secret lemonade drinker]

Big cross section cables so the volt drop is less, a cheap way to get the necessary cabling is to buy some flexible jump start cables and use them, good quality gold plated battery terminals with threaded terminals, don't use crimps as you are just adding resistance which is volt drop. Be careful to ensure that your charger can current limit or when charging effectively 0ne 200Ah battery the inrush current will blow the 50 or 75 amp fuse and cook the charger.

Ebikes would need a dc to dc converter.

 

[Beaker]

if you leave the earth where it is, you can take the supply side across to the new (third battery) like this:

The correct way is to bus bar both the +ve and have equal length cable. Local -ve or busbar the -ve as well. It is to do with the resistance and potential difference between the different lengths. Especially should one battery fail and produce a high internal resistance.

 

[Tarquers]

The correct way is to bus bar both the +ve and have equal length cable. Local -ve or busbar the -ve as well. It is to do with the resistance and potential difference between the different lengths. Especially should one battery fail and produce a high internal resistance.

Sure the professional installer that provided the info will appreciate the comments.