Planning on the Future

[EdRedBird]

HI

New here
Just after buying a 2010 Transit MK7 and striping her out.

I am initially going/planning for a split relay of two serial leisure batteries,
Solar will be an option that I will add later....
But what do I have to keep in mind planning for this?

I have 2 batteries under the driver seat (The MK7 has its own leisure battery for some reason)
I will run the relay of the main battery to my two serial LB's and run an inverter of these 2

IF and when I want to start feeding my LB's via a source other than the the main battery

The simplest and cheapest options I see
a 2 or 3 or 4 way switch : 1 No charging/decharge 2: Switch Relay Charging 3 Solar charging 4 External feed
Are there any other elegant solutions and wiring schema's

Thanks

 

[autorouter]

Yes there are simpler solutions. All these devices like the alternator, solar charge controller and mains-powered charger have a diode (an electrical one-way valve) in their output. This prevents any unwanted backfeeding from one device to the other. The result is, you can just connect them directly to the battery and not worry about it. No switching required. (Through a fuse of course. All wires connected to a battery require a fuse)

The split charge relay has three main functions.
First, it disconnects the leisure batteries from the starter battery, so if you accidentally drain the leisure batteries flat, you can still start the engine.
Second, it keeps the leisure batteries disconnected from the starter battery while the starter motor is starting the engine. The starter battery takes a huge current (hundreds of amps) from the starter battery. You don't want the leisure battery involved in that, it's not built to do that kind of thing.
Third, when the engine is running, it connects the leisure battery to the starter battery, so they are both charged by the alternator.

It is important that the split charge relay is triggered by the correct command. It needs the D+ signal, which the alternator sends when it is up and running, when the engine is running and the starter has finished its job. This D+ signal is not the same as the ignition signal. When you turn the key, the dash lights come on - that's the ignition signal. When the engine starts, the alternator light goes off - that's the D+ signal.

And I'm not sure what you mean by 'two serial leisure batteries'.

 

[EdRedBird]

autorouter Thank you
Additionally: My Transit has 2 batteries under the driver seat
One is for starting the other sees to be an sort of leisure battery already

I found this very clear explanation and I am 99% sure I want to go for #2 in the timelinked video


BUT

Do I come off my Ford leisure or fort starter
(And out of curiosity how are the 2 ford ones connected?)

 

[EdRedBird]

Deep Cycle Battery Charging with your Alternator: The 3 Best Options explained [+ Wiring Diagram] (Youtube)​

 

[mitzimad]

if its difficult to find a dplus signal use a smartcom relay to generate a signal to a second high ampage relay. The feed for the smartcom can be from any live wire set the smartcom to make at above 13volts. I use 100 amp relays as you get studs to connect ring connectors which are best for the size of cable you need between the main and leisure batteries 16mm2 minimum bigger if its a long run

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[mitzimad]

if your planning on staying off grid for more than a few days solar is essentiali would be looking at cable runs now from roof to where you intend a controller to go

 

[Lenny HB]

I have 2 batteries under the driver seat (The MK7 has its own leisure battery for some reason)

One battery is for the starter the other is for the engine/base vehicle electrics.
You need to fit additional batteries for leisure use.

 

[EdRedBird]

mitzimad Electonics I understand on paper , the terminology involved is sometimes like ordering chinese , I am getting pork with tumbleweed
dplus? And I understandcable gauges as in reason why not calculation.... but it makes sence to plan on adding additional sources and/or appliances

Seems like Renogy MPPT does what I need/want idiot proof I am very open to other simmilar devices

and from there a nice 2kw inverter

And yes I will have to tidy any (future solar) cables away within the wall and or ceiling

I am probably going for Bank and DC-DC in the back for access

 

[EdRedBird]

Lenny HB Yep I got that bit... but how are these wired ... if Serial it does not matter but if parellel...from which do i take my feed to Dc-DC

 

[Raul]

Sounds like you need to brush up on electrics.
Series wired does matter, will make it 24v.
Parallel will increase capacity, but voltage will stay the same.
A 2kw inverter will need 800ah of lead battery to use it at its full. It will kill a small bank.
Have a look at Craig Virgoe series on YouTube, for van build. He has the right bases on all aspects. Tweak to suit yours where applicable.

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[autorouter]

Many of the devices you'll want to fit in a motorhome or campervan work from 12V. Things like the water pump, lights, fridge, heater control circuits and many other things. It's best to keep everything at 12V. For that reason, 12V batteries are wired in parallel, which keeps the voltage the same. Not series, which increases the voltage, to 24V for example.

In an off-grid house running on solar, there's usually a battery which just feeds an inverter. The inverter converts all the battery power to 240V AC, so that normal mains appliances can be used. In that situation the battery voltage is not important, so 24V or 48V systems are common. In a motorhome that doesn't apply, so most stick to 12V for everything, and avoid higher voltages.

It's not impossible to have two different voltages, but if you're not sure how everything works it's a big extra headache.

 

[EdRedBird]

Raul you are right ..picturing the wiring right ...named it wrong (Cause in all the schemas the negative runs paralel to the ... doh
You meantion specifically Lead battery though ...Any pro's on that vs agm?
Also intrested in the maths behind a 2kw inverter will kill <800ah battery (Not that I intended on going less)

I presume that the TWO STANDARD batteries in my transit are not wired series, that would eventually defeat the purpose of the "leisure battery" and drain the starter ...
Do i take my feed to DC-DC (renogy) of the starter or the leisure battery?
(What is best practice)

autorouter Merci beaucoup. I had understood that 24v would give a better true sine on a converter and with 4 batteries you could put two PARALEL banks in SERIES. and then run the inverter off that . Doing away with that idea ... 2 batteries paralel to start off with

 

[Raul]

Lead acid comes in tree main flavours, apart from more modern doping of calcium, carbon etc.
There are tree distinctive types of lead acid types:
-AGM sealed for life, and the electrolyte is in the Absorebed Glass Matt.
-Flooded, where the electrolyte is loose, in direct contact with the plates; this can be sealed flooded, or open, where you can add water.
-And GEL, where the electrolyte is in gel form covering the plates.
All this types have the same chemistry, lead plates and acid electrolyte with a mix 1,2-1,3 concentration. They all are restricted on charging and discharging limits, directly by the chemistry and construction type.
In reference to my words in previous post, is based on a C/5 discharge rate. C-total capacity 800ah divided by 5. Resulting in 160a discharge. Times 12v, resulting in 1920w. If you push more then these batteries are not built for that.

 

[autorouter]

Do i take my feed to DC-DC (renogy) of the starter or the leisure battery?

Normally it is taken from the starter battery, with a big fuse very near the starter battery. The link from the alternator to starter battery is a permanent link, and can cause all kinds of problems if it's not 100%. Leave well alone. Your DC-DC charger only switches on when the engine is running, and the alternator is supplying power. So it never drains anything from the starter battery. The alternator charges the starter battery at the same time.

 

[EdRedBird]

In reference to my words in previous post, is based on a C/5 discharge rate. C-total capacity 800ah divided by 5. Resulting in 160a discharge. Times 12v, resulting in 1920w. If you push more then these batteries are not built for that.

OK ... ?..
Why the 5 .. (20%?)
P=I*V V=I * R P = R* I ^2 etc

I am eyeing up SuperBatt AGM1100 12V 120AH
2 of them (Paralell would give me 240AH -> 574w

Damn at that rate I am going to need that towbar...to fill a trailer as battery bank

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[Tombola]

Greg Virgoe

 

[Tombola]

OK ... ?..
Why the 5 .. (20%?)
P=I*V V=I * R P = R* I ^2 etc

I am eyeing up SuperBatt AGM1100 12V 120AH
2 of them (Paralell would give me 240AH -> 574w

Damn at that rate I am going to need that towbar...to fill a trailer as battery bank

240ah but only 120ah useable if leads.
Have you not thought about lithiums if you are going for a big bank ?

 

[autorouter]

Why the 5 .. (20%?)

There's a limit to how fast you can charge or discharge a battery. If you try to discharge too fast, you get problems like overheating and gassing. The different types (Flooded, AGM, Gel) have slightly different tolerances. The usual rule of thumb is to limit the maximum amps to C/5, where C is the battery capacity. Gels have a lower tolerance, flooded have a higher tolerance, but C/5 is a good target to aim for.

Starter batteries have a high tolerance (as seen by their CCA value), but only for a short time (a minute or two).

One of the many advantages of Lithium batteries is the higher charge.discharge rates - C/2 is common, C is possible, and some will go even higher.

 

[Raul]

What he said, or simply put, limited by chemistry. Batteries do not store electricity as such, but a chemical reaction takes place, that moves electrons. The chemical reaction has limits.

 

[mitzimad]

On a transit it doesn't matter which battery you connect to as you will only draw current when the engine is running

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[mitzimad]

Personally I wouldn't put any wiring behind panels unless unavoidable

 

[EdRedBird]

autorouter Lithium is going to break the bank for the moment eventually that is the plan though
Tombola yes the 50% use

I guess I have to start somewhere, and it is a fine line between budget and selling myself short
Any battery on a budget suggestion is welcome

Renogy 50A DC-DC On-board Battery Charger with MPPT should at least give me the option of adding solar in the future
(Though I am open to recommendations)

They also do a true sine ionverter that would alow me to plug in (and charge) via shore .. Not planning to use shore... but considering if it is worth the extra few £

Personally I wouldn't put any wiring behind panels unless unavoidable

Plan is:
Leisure batteries under pasenger chair AND/OR ..... raised floor behind the chairs (swivel seat and passenger with short legs)
Have my battery bank DC-DC and inverter siting there and run the rest lights sockets and USB from there through the rest of the van)
I want to keep my 4 or 6 gauge cables as short as possible .



I am still curious about that second battery. (I have not taken the driver seat off yet)
I presume that they are not paralel : as the it would eventually deplete the starter battery?
If that is the case there is some DC to DC system in place between the batteries?
Would it then not be possible to put the "house battery" paralel with the standard "leisure battery"
In other words.... do I need a DC-DC controller or is there one present?

 

[autorouter]

I am still curious about that second battery. (I have not taken the driver seat off yet)
I presume that they are not paralel : as the it would eventually deplete the starter battery?
If that is the case there is some DC to DC system in place between the batteries?

I knew nothing about Transits, but having watched a 3-minute You-tube video I am now a world-class expert. In the video he removes the battery cover showing the two batteries under the seat. The two batteries are connected together, in parallel, by simple wire links, positive to positive, negative to negative. So the two batteries are acting just like one big single battery. I'm disappointed, I was expecting at least a split charge relay or a diode.

 

[EdRedBird]

autorouter looked up youtube on a lot of things...but not that .... Why the H are they referring to it as a "leisure " battery that supposedly support the standard electronics? And how come people claim the back one is the starter? I feel had\
In work so I cannot watch that video at the momen, i just hope they use the bankl correctly to go from - at one and + on the other
(Though that would explain why people have on drained battery in those fora)

"Great" no cheap shortcut for me there so