12v lighting for my house powered by my van

[12vshocker]

hello all is this possible????

I drive a van around all day, I want to use the van to charge up a 110ah Agm battery, I then want to use this battery to power up a 12v led lighting circuit in my house. I also want to use the 240v supply as a back up to the same lighting circuit, with some sort of switch over device for when the agm battery voltage gets low.

Essentially I will have 2 batteries in rotation, charging one all day why the other is being used

Any idea if this set up is used any where and how well it works, or where to find the calculation to see how long a fully charged 110ah battery would last

I don't want to use a inverter, just the transformers already build into the Selv lighting, and diodes to stop the 240v system back feeding into the 12v system.

Is this possible, (not too bothered about it being economical)

Let me know your thoughts and criticisms

 

[PJElectricalSW]

Insanity at new levels, I agree that it seems daft but if the OP has legit and honest intentions then surely we should offer advice.

And you'll be wanting a voltage drop relay, try Finder or Schneider for help on this one.

The cost of this setup is likely to reap little for you, it would be cheaper to buy solar torches/lamps and bring them in of an evening.

 

[DPG]

Remember car batteries are not intended to be deep discharged, so as PJ says above you will need some sort of voltage monitor to cut off before the battery voltage gets too low.

 

[Michael Sands]

Just use company fuel to power generator the set up you are suggesting is just insane and potentially kill someone by electrocution or fire
To calculate power usage it should simply be amps per hour 10 bulbs using 1 amp each would use ten amps per hour a simple calculation of ohms law will work fine to work out amps used per lamp
There are loads of channels on YouTube about power walls made from reclaimed batteries maybe that would be a better place to have your questions answered

 

[Deuce]

I've solved this.

Instead of transferring the power from the van... Just leave the 12v lights turned off. Then park your van, leave the engine running and headlights on hi-beam shining through your window

 

[Squid]

Work harder earn more money and then you don't have to worry about your electrikery bills, simples.

 

[Silly Sausage]

Work harder earn more money and then you don't have to worry about your electrikery bills, simples.

Just fiddle the meter

(Disclaimer: my posts are just opinions, not necessarily to be taken seriously )

 

[Squid]

Just fiddle the meter

(Disclaimer: my posts are just opinions, not necessarily to be taken seriously )

You worry me sometimes with your choice of words..........'o)))))

 

[Lucien Nunes]

Let's be clear about the economics here.

The average cost per kWh in the UK at the moment is around £0.14.
A 110Ah 12V battery stores (very approximately) 110x12/1000 = 1.3kWh or £1.85 worth of electricity. It's not exactly that figure because the voltage is not 12V over the full discharge, and the 110Ah is quoted at the 20-hour rate but will be less if discharged in less than a day. Let's assume a reasonably optimistic 80Ah representing 100% depth-of-discharge to 10.8V over a full life of about 400 cycles. We can't really push it any harder because of the fairly aggressive charging rate required quite apart from the discharge.

The OP must supply his own battery, even if he's stealing the fuel used to generate the power. To get the performance mentioned he will need a good quality battery. 110Ah non-traction AGMs range from say £120-200. If he spends £175 he will get a good brand that will hold up to this kind of use. A traction battery rated for discharge at C/5 will do better at correspondingly higher cost.

Each daily cycle saves him 80 x 11.5 x 0.14 = £ 1.29 in electricity but costs 175/400 = £0.43 in battery wear and tear. So the maximum possible saving on this scheme is around 86p per day. I would be surprised if, in real-world changing conditions, you would achieve half that.

To quote the wise words of Dave OCD's post:

Why even bother.

FWIW, you can use a pair of diodes to allow a backup mains-driven PSU to take over seamlessly when the battery gets low. You set the voltage of the PSU equal to the minimum voltage to which you want to discharge the battery. Whichever is higher does the work. Use big, low voltage Schottkys to avoid undue losses.

As mentioned above, heavy cables will also be needed to avoid yet more undue losses. For those unfamiliar with transmitting power at 12V, the power loss is 367 times greater than at 230V for a given power and cable size (230/12)². E.g. the headlamp feeds on my boat are 10mm² (tunnel lights) and 16mm² (spot lights). 24V makes a 75% saving in copper over 12V.

 

[Shoei]

Let's be clear about the economics here.

The average cost per kWh in the UK at the moment is around £0.14.
A 110Ah 12V battery stores (very approximately) 110x12/1000 = 1.3kWh or £1.85 worth of electricity. .....

Logic is spot on, you probably looked at your calculator in disbelief and unconsciously moved the decimal point. It's 18.2 pence for 1.3kWh.

If everything is 100% efficient and the batteries never degrade it takes about 5 years to break even, in real life, break even is approximately never.

 

[Lucien Nunes]

Yes, well spotted! Made a crucial slip there, I accidentally switched from visualising what the OP's single 110Ah battery holds, to what the battery complement on a recent project holds (just over 1100Ah) and subconsciously changed the numbers as I typed so that they made sense. As I've often used as an example, the average person cannot lift £1 of electricity stored in lead-acids.

So yes, the battery saves less than 20p of electricity per cycle but costs more than that in depreciation, hence the scheme makes a net loss.

 

[Deuce]

Each daily cycle saves him 80 x 11.5 x 0.14 = £ 1.29 in electricity but costs 175/400 = £0.43 in battery wear and tear. So the maximum possible saving on this scheme is around 86p per day. I would be surprised if, in real-world changing conditions, you would achieve half that.

It's even more pointless than that - as there is no way he's going to burn through £1.29 of power per day just running the 12v lights in anycase.

The average UK home uses about that much per day across all circuits so...

It would genuinely be more sensible (or less stupid??) to leave the van running, and fit a cheap inverter to provide a 230ac supply from the van to the house.. That's an equally silly but far more economic way of turning company fuel into home power than pushing it into batteries and swapping them each day.

EDIT: Since seen @Shoei 's post and the decimal point mistake. Whatever, it's still more economical to take the power direct from the van than to try and store it

 

[davesparks]

If the aim of the game here is indeed to use company diesel to provide electricity then it would be better to buy a diesel generator and syphon the fuel out of the van to fuel it.

 

[Deuce]

If the aim of the game here is indeed to use company diesel to provide electricity then it would be better to buy a diesel generator and syphon the fuel out of the van to fuel it.

Jeez, now the OP has to find a diesel generator to steal too!!