dual leisure batt system + aux battery

[wolfbus.uk]

planning the electrical stage of my syncro panel van conversion.

I have a sterling AB12160 charger as yet uninstalled.

I am trying to find the most effective way of having an interchangable 1,2 or 3 x 125AH battery system that can be altered to suit whatever we do in the Syncro without detriment to two of the batteries always being a well matched parallel 12v 250 AH battery bank.

The two 125AH AGM batteries weigh 68KGs & dont want to use them when using vehicle as a daily driver/ weekend camper. Just want to put them into circuit for longer serious travelling i.e two month 6000 mile + trips generally in winter.

I am thinking the easiest way to do this is have the 2 x Lifeline AGMs in a removable box that is only mounted in the vehicle when needed & the aux battery is just strapped in but not in circuit then.

But.. Is there a way of keeping the aux battery & parallel bank in potential circuit with the Sterling & the leisure set up but still have the aux & parallel bank isolated from one another & switchable either under load or charging? It would seem a waste to continually discharge two £450 deep cycle batteries for light use. So in a scenario of a road trip we might be driving to Dover or just passing through a country (like Belgium!) needing to use the leisure set up but where the aux battery alone would be perfectly suitable for this, & only switch over to the parallel set up when circumstances need true deep cycling. Or would it be better to run a second intelligent charger for the aux battery & have an isolator switch for the parallel bank. I understand that I could just change the terminals leads from the aux to the parallel's & vice versa but this would not be an ideal set up & I don't like touching batteries with spanners at the best of times!

electronics is not my forte so apologies if there is a very simple solution I have failed to see.

[CJH]

You could use a battery changeover switch, like this one. You'd have the two parallel batteries wired to, say, position 1, and the auxiliary battery connected to position 2, and you could then chose either, both or none.



To make the parallel bank easy to remove from the vehicle, you could use some big Anderson connectors, like these.



The main practical problem with switching batteries in and out of circuit like this is that they should ideally be at similar levels of charge when they're joined together, since otherwise there will be very high current flow from the higher charged battery to the lower charged battery. In practice this would mean you'd have to separately charge both the auxiliary battery and the parallel bank before setting the selector switch to 1+2.

[wolfbus.uk]

thanks the Bowers switch looks exactly the ticket & very simple answer to what has been doing my head in all day!!! & the Anderson connectors are a namesake so also a must

I asked an electrician these questions earlier but he felt it would be a rather overcomplicated faff Then again he is not the one spending out on the batteries!

Glad you understood the basic concept of the system but just to say the switch would never be set 1 + 2 & have the parallel bank working in tandem with the single aux battery. The whole point is to always preserve/protect the 2 x parallels & use the aux as a general dogsbody! So when I really need the parallels they will be in tiptop as condition as possible & only ever used with their twin for deep cycle duty.

My syncro owes you a beer for not having to lug around an extra 68kg when not needed

The third aux battery will be a Rolls 128 AGM, if anyone has good or bad experiences with them it would be good to know.

The other problem I felt planning this Sterling set up was that the Sterling seems to always charge batteries even if you don't want it too. It appears this switch up deals with that too & will isolate not only both banks from each other but also from the Sterling & give the poor alternator a break!

Cheers!

[CJH]

Keeping your expensive parallel batteries connected, so that they live and work together their whole lives, seems like a good idea. For the wiring there's a way to connect up a bank of batteries so that they all charge and discharge at exactly the same rate, and therefore age at the same rate. There's a good article here. In the case of two batteries it's quite simple - just take the positive from one battery and the negative from the other out to the Anderson terminal. For the case of four batteries below, the article shows a better configuration, but for just two this configuration is optimal.



Having said all that though, I should say I have two batteries in different parts of the van, that are connected in parallel via one of those battery selector switches, and so far they've been fine together.

Also, that 175A Anderson connector I linked to is probably overkill for a leisure setup, although I know that the Sterlings can put a hefty charge into a battery. I don't know what other versions of that connector there are - there's certainly a 50A version, but that might be a bit tight for the charge that the Sterling can provide. And the other consideration is the resistance. As the article above points out, you want to avoid resistance in the interconnects, so the bigger the connector the better.

[wolfbus.uk]

thanks for the link. It looks quite simple for two batteries compared to some of the diagrams on that page! For a two battery bank system I am guessing that the sterling & load will be on the common terminal of the marine switch & one of the positives from each bank to the 1 & 2 switch terminals so that when the switch is moved from off to 1 for instance, that will connect Sterling to the fuse board & load via the chosen battery bank. The Anderson connectors would terminate the output from the 1 + 2 terminal I suppose.

May possibly do the first stage of the wiring in a week or two so I have until then to theorise everything... eeks!!

For now I think this looks a good system but without having an electrical system to use I have no idea of general consumption & for winter overlanding even less of an idea, so perhaps looking at other peoples set ups will provide some answers. I am guessing at 40AH a day would be enough to just about survive in difficulties.

It does seem apparent though that the parallel bank should be as large as possible & more than two thirds the total of all batteries to keep the potential discharge percentage as low as possible. Perhaps an ideal set up would be two 6v 300AH's in series & an 85AH battery for general dogsbody. Hopefully 125 + 125 for the parallel & 125 for general use/emergency battery will be a strong enough system but I need to really do my maths before buying any batteries! The other limiter is space. It all, quite typically, has to fit in a ridiculously small & angled area. Approximately 580L x 275D x 350H under the R&R seat. Something like Tetris with wires, marine switches, batteries & a big cumbersome VW mat!!!

If you ever get a chance to take a photo of your wiring set up with the switch that may be helpful too.

Thanks for your input.

[CJH]

thanks for the link. It looks quite simple for two batteries compared to some of the diagrams on that page! For a two battery bank system I am guessing that the sterling & load will be on the common terminal of the marine switch & one of the positives from each bank to the 1 & 2 switch terminals so that when the switch is moved from off to 1 for instance, that will connect Sterling to the fuse board & load via the chosen battery bank. The Anderson connectors would terminate the output from the 1 + 2 terminal I suppose.

Yes, apart from the Anderson connectors. I suggested these as a way to remove your parallel batteries when you're not using them. Maybe a diagram of the layout I had in mind would help.


But your parallel batteries are going to be heavy, and difficult to move as a pair, so maybe there's no benefit to the Anderson connectors after all. Maybe just a couple of pairs of quick release connectors would be better - like these:

Perhaps an ideal set up would be two 6v 300AH's in series & an 85AH battery for general dogsbody.

If you're thinking of the Trojan 6V batteries then they certainly get highly recommended on this forum. I believe their benefit comes from being a very sturdy construction, so they can be run flat without the plates distorting, so they make very good leisure batteries. But there's no saving in volume - 2x300AH at 6V will give you 1x300AH at 12V, and 300AH at 12V needs a lot of battery. Think of them as two halves of a 300AH 12V battery. Just check the dimensions before buying.

If you ever get a chance to take a photo of your wiring set up with the switch that may be helpful too.

I have my electrics on a panel in the wardrobe. This photo shows my battery selector switch.

[CJH]

Maybe just a couple of pairs of quick release connectors would be better - like these:

One further thought about this - Anderson connectors are very well thought out - there are no exposed terminals, and connection is foolproof. The quick release terminals on the other hand have exposed contacts when they're not connected to a battery. If you use the battery selector switch, then if ever it's put in the '1+2' position, even for a moment, when the parallel batteries aren't in the van, then the quick release clamps would be live thanks to their direct connection to the auxiliary battery. Just something to consider.

[georgedoors]

I have my electrics on a panel in the wardrobe. This photo shows my battery selector switch.

[/quote]

Hi, sorry to butt in, just after a few answers regards your wiring setup as in picture please. Just got same system and getting ready for install, it's the connections to the ctek units I'm asking about? I can see two cables coming in from left hand side one from solar into top of dual 250, but you also have another cable coming in from left hand side split into black into dual 250 vehicle ground and red into smart pass service battery, can you confirm if this is where you put your MX5 charger leads into the system?

Thanks, Paul..

[CJH]

I can see two cables coming in from left hand side one from solar into top of dual 250, but you also have another cable coming in from left hand side split into black into dual 250 vehicle ground and red into smart pass service battery, can you confirm if this is where you put your MX5 charger leads into the system?

Hi Paul - yes, that's how I've wired it. The D250S manual is here. Page 21 is titled 'Connecting AC/DC Chargers', and it says:

The single output 230/110V charger is connected directly to the Service battery. The Starter battery is pulse charged through SMARTPASS.

Since the two terminals you described are connected directly to whichever leisure battery I have connected through the switch (usually both), then this was a convenient place to connect the charger.

[georgedoors]

Thanks for the reply, I had looked at the manual and saw it said about connecting charger directly to service battery, which was the route I was going to go down, but as you say connecting it through the ctek units does the same thing and is looking like the easier option for my fitting too.

[wolfbus.uk]

this is a different question but for the same install so thought i'd write here than use open a new thread.

I am pretty eager to get my ply lining panels up soon before they start to warp but firstly need to do some basic electrical wiring.

https://www.flickr.com/photos/134122268 ... ed-public/" onclick="window.open(this.href);return false;

the above picture shows the wiring that is going below lining & probably a few aux wires for future mods.

Now as this is entirely new to me, rather than just throw wire in like spaghetti I want to work out if there is a better way when we are dealing with up to ten, 12v connections in a small isolated area a couple of metres from the main fuseboard.

The main areas of electric usage in my build are the R&R bed where the batteries etc are to be installed so I think this will be quite straight forwards.
The two other main areas are; the front bulkhead drawer system. There will be between six and ten 12V connections needed here. Also the sidewall opposite side loading door, there will be upto ten 12v connections here. (mostly chargers 4x cig chargers and 4 x USB) I do photography so need plenty of charge outputs also my feeling is that you can't have enough cigs sockets just in case!

So from the main junction/fuseboard which will be under the R&R bed am I best to run a 2x 30A or so + & 0v cable to another fuseboard or bus??? and from there run off individual wires to each application or do folks just run a gazillion smaller wires through conduit from the main junction box?

Any help greatly appreciated as I am trying to get the bulk of this wiring done before next weekend.

The two fans in the rear side windows and LED light there, as in photo, this is only using 5 wires each side and is a lot closer to battery so will just run individual wires from fuseboard here I guess.