Design feedback on solar/electrical system (1 Viewer)

[Red_48]

I'm looking for feedback on the design of my Sprinter vans solar/electrical system.

Design choices I have made are:

12-volt use only when off-grid.
Shore power to charge leisure and/or starter battery.
Alternator to charge the leisure battery.
250Ah battery should provide 3-4 days of off-grid power during inclement weather (based on load/usage calculations).

Questions:
Are componants sized appropriately?
Can the design be improved in terms of utility, efficiency, and simplicity?

I really appreciate feedback from those with experience.

 

[TheBig1]

the alternator will not be sufficient to charge the large leisure battery, you will need a battery to battery charger

 

[Deleted member 29692]

the alternator will not be sufficient to charge the large leisure battery, you will need a battery to battery charger

Or a battery master

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[Deleted member 29692]

Looks unnecessarily complicated to me.

Mine is Solar Panels ----> Fuses -----> Controller ------> Leisure Batteries.

There's also a battery master taking care of the engine battery.

Job done, works perfectly all year round.

And before anyone starts it's a professional install not a DIY one

 

[TheBig1]

a batterymaster cannot charge at 40amps

 

[Deleted member 29692]

a batterymaster cannot charge at 40amps

Does it need to? Our engine battery has never run flat.

I've always thought that if everything else is set up properly B2B is over the top. Fine if you don't have solar but not needed if you do.

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[Red_48]

Looks unnecessarily complicated to me.

I'm all ears Nick.
How does your system meet the same design requirements? I.e. Shore power to charge leisure and/or starter battery.
Alternator to charge the leisure battery.

I'm all for simplifying things without losing utility.

I'll look into a battery master. Thanks

 

[Red_48]

Would a generator attached to the shore power input suffice to charge the vehicle battery with the leisure battery isolated?

 

[Reallyretired]

Your mains sockets are not earthed according to your diagram, also no overload circuit breakers on the mains, just an RCD

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[Red_48]

Thank you Reallyretired... I'd mistakenly thought an RCD would deal with overloads as well as jumps to earth.

Great feedback Sir

 

[TheBig1]

the b2b is to charge the large leisure battery by running the engine when the solar cant keep up with draw

 

[pappajohn]

Would a generator attached to the shore power input suffice to charge the vehicle battery with the leisure battery isolated?

Why would you want or need to.
The vehicle battery should be fine for a reasonable time if left out of the equation completely.
If necessary, a simple Batterymaster charger would keep it topped up directly from the leisure battery as and when needed. Your method would have the engine battery on constant charge whether needed or not.

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[Red_48]

Would a battery-to-battery charger sit in between the alternator and the vehicle battery or the vehicle battery and the leisure battery?

 

[gus-lopez]

 

[TheBig1]

Would a battery-to-battery charger sit in between the alternator and the vehicle battery or the vehicle battery and the leisure battery?

it takes the feed from the alternator and uses electronics to trick the alternator to supply a full charge to the leisure battery. the alternator would otherwise drop to minimal once the van battery had been topped up

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[DBK]

Would a battery-to-battery charger sit in between the alternator and the vehicle battery or the vehicle battery and the leisure battery?

Whether you need a B2B charger is down to how you plan to use your vehicle. A B2B charger is not cheap and I suspect 99% of MHs don't have one and get along fine.
If you find you need one it could be added later so I suggest ignore it for the moment.

You need an inexpensive split charge relay to charge the leisure batteries when the engine is running and as suggested a battery master to do the same for the vehicle battery when on solar or EHU - this is the usual setup and for a reason, it works. You dont need manual switches when it can be done automatically.

I would also add some instrumentation so you can actually monitor what is going one. The NASA BM1 or the equivalent Victron model would be fine. These work on a shunt in the leisure battery feed and will tell you the state of charge, voltage etc.

 

[mitzimad]

a big battery is hard to move which is why most setups will use two smaller batteries
in practice your bus bars will be multiple connections to the battery terminals unless your batteries are a distance from everything else
you dont show any fuses for the 12v side
either a b2b or a split charge in place of your manual switch everyone ive known with manual change over has been stranded with flat batteries at least once
you dont show a fridge? if its a 12v compressor like a waceo youll need a good sized 12v supply for that direct from batteries if its a three way you will need a relay to send a 12v supply to it when the engine runs it also needs a permenant 12v feed for the electronics and light

 

[autorouter]

The shore supply needs looking at again. If you think that circuit diagram is accurate you definitely need professional advice.

An RCD is double-pole - in other words, it switches both the live and neutral wires. It protects against electric shock but not overcurrent.

An MCB may be single or double pole. It protects against overcurrent. A double-pole one is best, but difficult to find in the UK.

A combined unit called an RCBO contains both functions. It is usually more expensive than a separate MCB and RCD.

I don't know where you get the '110/240V' AC supply from, but that's not what you get this side of the Atlantic Ocean. It's straightforward 230 volts AC over here.

Also you need to look at the leisure battery to starter battery connection. When the engine starter is running, there is a huge current from starter battery to starter motor. If the leisure battery is connected to the starter battery, part of the huge current will come from the leisure batteries, which is probably not what you want.

This is usually avoided by placing a relay between the two batteries. The relay switches off when the engine is stopped, and while the engine starter motor is running.

Once the engine is running and the starter motor is no longer powered, the relay switches on to allow current from the alternator to charge the leisure battery.

I can see nothing in this circuit that performs this automatic switching function. This device, called a split charge relay, is standard on motorhomes and caravans.

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[tonyidle]

The shore supply needs looking at again. If you think that circuit diagram is accurate you definitely need professional advice.

An RCD is double-pole - in other words, it switches both the live and neutral wires. It protects against electric shock but not overcurrent.

An MCB may be single or double pole. It protects against overcurrent. A double-pole one is best, but difficult to find in the UK.

A combined unit called an RCBO contains both functions. It is usually more expensive than a separate MCB and RCD.

I don't know where you get the '110/240V' AC supply from, but that's not what you get this side of the Atlantic Ocean. It's straightforward 230 volts AC over here.

Also you need to look at the leisure battery to starter battery connection. When the engine starter is running, there is a huge current from starter battery to starter motor. If the leisure battery is connected to the starter battery, part of the huge current will come from the leisure batteries, which is probably not what you want.

This is usually avoided by placing a relay between the two batteries. The relay switches off when the engine is stopped, and while the engine starter motor is running.

Once the engine is running and the starter motor is no longer powered, the relay switches on to allow current from the alternator to charge the leisure battery.

I can see nothing in this circuit that performs this automatic switching function. This device, called a split charge relay, is standard on motorhomes and caravans.

Other than @autorouter comments there's little wrong with your circuitry. I woud suggest, as others have, that you maximise use of the alternator by using a b2b unit.

 

[scotjimland]

no overload circuit breakers on the mains, just an RCD

no overload circuit breakers on the mains, just an RCD

incorrect

I'd mistakenly thought an RCD would deal with overloads as well as jumps to earth.

You were correct

The RCD is also an CB rated at 16A

That is what is fitted in my Hymer.. with no other CBs

This popular esr RCD is suitable for installation in esr Consumer Units.
esr RCD works by detecting overcurrents due to both overload and fault currents.

https://www.elementlighting.co.uk/c...AkKHEALw_wcB&zenid=ok40f9jkg4h22upkra4rpga7n5

 

[Reallyretired]

I stand by What I said. The diagram only mentions an rcd not an rcbo as in your link.

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[Deleted member 29692]

the b2b is to charge the large leisure battery by running the engine when the solar cant keep up with draw

Like I said, unnecessary. Or it is for us anyway. Our solar has never not kept up.

 

[scotjimland]

I stand by What I said. The diagram only mentions an rcd not an rcbo as in your link.

fair point.. it doesn't,

perhaps he didn't realise there is a difference between RCD and RCBO .. or it was an omission on the drawing

in any case, now it has been highlighted he can buy the correct one for the job..

Edit ..

this is the problem with unqualified DIY electricians

Just noticed on the drawing, the RCD is shown as single pole

According to 17th caravan regs, The RCD should be DOUBLE POLE>>

The RCD must comply with BS EN 61008-1 or BS EN 61009-1, interrupt all live (line and neutral) conductors and have the characteristics specified in Regulation 415.1.

 

[autorouter]

Sorry to bang on about this, but that link is to an RCD, not an RCBO. The web site description is wrong.

Look at the RCBO description and you will see it is identical apart from the letter O.
https://www.elementlighting.co.uk/c...cbo-16a-30ma?zenid=ok40f9jkg4h22upkra4rpga7n5
The RCD in the first link will NOT protect against overcurrents. The guy who does the web site just cut and pasted the description text. Careless, but quite common on technical web sites.

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[scotjimland]

@Red_48 Just for reference.. extract 17Th edition IEE Regs Caravans and Motorhomes, may be useful .

 

[Lenny HB]

He is doing the conversion on a Merc so it will probably have a smart alternator so will need one of the electronic control boxes that flools the alternator so it doesn't shut down. Hymer fit a Schaudt unit and I think Votronic make one as well.
Also most Motorhomes have an uprated alternator (Hymer fit 160 amp one) will the standard one be up to it.

 

[scotjimland]

Just for information, this is the device fitted to mine..

Residual current operated circuit-breaker with integral overcurrent protection (RCBO)

Rated current (AC) 13 A

Rated residual current I∆n 0.03 A

sold by Amazon
Amazon product ASIN B074GC5GXX

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[PhilandMena]

Do you think 300 W of solar panel will be enough?

 

[Red_48]

Posting privileges restored!!!!

Very frustrating to read comments that I can't contribute to.

Amended diagram a few days ago with a B2B, and a breaker in addition to an RCD on the AC side.

Please feedback (including comments on size). My current daily load estimates are 147Ah (1772Wh).

 

[Lenny HB]

You have the RCD on the wrong side of the input socket, & do you have a smart alternator.
Something wrong with your figurers thats 113 a/h a day - unsuportable.
E.g. Fantastic fan draws only between 0.5 to just over an amp on full. You would be better working your figurers on amps easier to understand as you normally calculate the power in amp hours.

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