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

 

[davesparks]

In theory anything is possible, but this would be very expensive to implement.

You couldn't use diodes to achieve the seperation of mains and battery, you would need to use one or more relays or contactors.
Also the 12V cabling would need to be of a very large size to overcome the voltage drop, and you'd need to design and install protection (fuses) to prevent fires.

 

[Deuce]

Just pay to power your own 12v PSU rather than fleecing the AH from your company van

Anyway, sounds like this could effectively be achieved using a UPS controller feeding the 12v PSU. You could use a time delay relay to switch on the 240v supply to the UPS every time the 12v supply holding the signal circuit relay open fails, and hold it open for say 12 hours to allow the UPS time to recharge the existing battery - just in case you fail to drive enough in the same time to recharge the other one

It's an interesting idea though... Using company/allowable expense fuel to pay for 'what could potentially be' private usage power..

Good luck to Mr Tax Inspector on figuring that one out

 

[telectrix]

i want a smartmeter that isso smart, it powers my house and the supplier pays me £50/week to use their leccy.

 

[Deuce]

Just to add to my comment above, obviously anyone looking to direct power generated from allowable company fuel for private use, should consider that whilst the power itself is not traceable, it's perhaps best not to post on a public forum to ask how to set-up an arrangement that 'could' be used in that way.

Jus sayin...

 

[telectrix]

who says it's a company van???? OP is in Enfield so it's more likely nicked. .

 

[Deuce]

who says it's a company van???? OP is in Enfield so it's more likely nicked. .

I won't stoop so low. There are plenty of honest folk in Enfield that would steal power from a company van without resorting to stealing someone else's company van

 

[Deuce]

All joking aside, electric cars are charged BIK at a flat rate including 'fuel' now, if the fuel is provided by the company you work for - presumably even if it's your own company, registered at your home address.

So what exactly stops a person trading as a ltd claiming that 80% of their household electricity usage is used to charge their company vehicle? And in the future, will we see people that work for companies that allow charging during work hours, find ways to liberate that stored energy for private use? I think Tesla are about to release a system that can take power from a car, as well as push power into the batteries. So charge at work for free and then power your house in the evenings!? I'm sure this will become a somewhat hot topic in the next few years as the government are pushing electric cars but it's more or less impossible to identify where the power comes from, and where it is used..

 

[KEV 1 N]

Just thinking out of the box here....
Could you not use a power unit from a caravan/motor home? Where mains voltage charges the battery, and the battery powers the 12v DC lights.
Use existing cables and switches and change the lights to work on 12v DC LED units.....and if it doesn’t work, just put it back how it was.

 

[Strima]

i want a smartmeter that isso smart, it powers my house and the supplier pays me £50/week to use their leccy.

Or just tap into all that unused neutral current that just gets sent back to the DNO...

 

[Gavin John Hyde]

Personally I would get a few hamsters and link their wheels in the cage to a couple of dynamos. failing that get yourself a couple of cheap pv panels and rechargeable batteries, link them up to some leds. quite easy to achieve.

 

[Deuce]

Or just tap into all that unused neutral current that just gets sent back to the DNO...

Or just rescue a few horses and put em to work?

 

[littlespark]

Voltage drop is going to be the problem... unless your house is the same size as a Ford Focus.

 

[Deuce]

Voltage drop is going to be the problem... unless your house is the same size as a Ford Focus.

I would assume the led circuit in question only requires 12v at source, why would it be a problem if the power comes from a 12v battery or the typical psu?

 

[Dave OCD]

Why even bother.

 

[Deuce]

Why even bother.

It does seem like a lot of effort to swipe a few AH each day from a van..

 

[davesparks]

I would assume the led circuit in question only requires 12v at source, why would it be a problem if the power comes from a 12v battery or the typical psu?

It will require 12V at the lamp rather than at the source. Led psus are normally located very close to the lamp, here the battery will be relatively far away.
Percentage volt drop is far worse at 12V than it is at 240V, dropping 2 volts in a 240V circuit is no problem, but losing it from a 12V circuit could stop a 12V Led from working.

 

[Deuce]

It will require 12V at the lamp rather than at the source. Led psus are normally located very close to the lamp, here the battery will be relatively far away.
Percentage volt drop is far worse at 12V than it is at 240V, dropping 2 volts in a 240V circuit is no problem, but losing it from a 12V circuit could stop a 12V Led from working.

I know... but why would the battery be further away than the mains>elv psu? The OP hasn't said it would need to be.

I may have missed something, feel free to point it out if so.

EDIT: Also I was once told most 12v leds will run down to about 9.5v anyway. We have run 3m ribbon from approx 10m, reading ~11v at the end of the run using 2.5mm.

 

[davesparks]

I know... but why would the battery be further away than the mains>elv psu? The OP hasn't said it would need to be.

I may have missed something, feel free to point it out if so.

EDIT: Also I was once told most 12v leds will run down to about 9.5v anyway. We have run 3m ribbon from approx 10m, reading ~11v at the end of the run using 2.5mm.

The battery would be much further away from the LED than the PSU would be because he is wanting to light the whole house from one battery, so for an average house you could be looking at maybe 40/50 metres of cable to some lights. Also the OP mentions SELV transformers at light fittings so this could be 50W MR16s rather than LED lamps.

My personal experience of volt drop in 12V circuits comes from fitting lights to landrovers where experience has shown that 4mm is necessary for even relatively short distances.

 

[Deuce]

The battery would be much further away from the LED than the PSU would be because he is wanting to light the whole house from one battery, so for an average house you could be looking at maybe 40/50 metres of cable to some lights. Also the OP mentions SELV transformers at light fittings so this could be 50W MR16s rather than LED lamps.

My personal experience of volt drop in 12V circuits comes from fitting lights to landrovers where experience has shown that 4mm is necessary for even relatively short distances.

But why do you assume the battery would be further away? He can't energise a circuit using a 12v battery that then feeds PSU's that have 240v on the primary. Surely the battery will go wherever the PSU(s) currently reside, whatever the actual arrangement/distance is.

I agree that in automotive voltage drop can be a killer, for various reasons. But most LED kit that is sold as 12v can run between 9-20v no issue at all. I'm not saying voltage drop doesn't occur, I'm simply saying it's often not an issue.

 

[12vshocker]

Ok so the plan is: to power the the lighting circuit using a car battery via a pcu, that connected the the a/c via timer circuit, fit a diode to the battery pos, so not to waste electricity recharging the battery with a/c power supply.

Is there a better way to click over to the ac power? I.e. Monitoring the battery status and some sort of automatic switch over once the voltage drops?

Also how do you calculate how long the battery would last, I know I'd need to find out the consumption of that circuit per day, and battery ratings etc but what would the formula look like?

And if I connected the neg post of the battery to the met bar would it tap into the unused neutral current (probably not the right word). Also I suspect something terrible would happens under fault conditions.

 

[12vshocker]

Sorry I meant UPS not PCU, stupid TLA's

 

[davesparks]

But why do you assume the battery would be further away? He can't energise a circuit using a 12v battery that then feeds PSU's that have 240v on the primary.

Because there is only one battery which he wants to feed the whole circuit from directly and he wants to install a diode to prevent the 240AC getting to the battery, he clearly hasn't got much of a clue.

From what I can understand of the OP this is exactly what he is intending to do, feed a whole lighting circuit at 12V directly from a battery.

 

[Deuce]

Because there is only one battery which he wants to feed the whole circuit from directly and he wants to install a diode to prevent the 240AC getting to the battery, he clearly hasn't got much of a clue.

From what I can understand of the OP this is exactly what he is intending to do, feed a whole lighting circuit at 12V directly from a battery.

I just... Can't believe that. He must surely mean the elv circuit on the secondary side of the PSU. not the entire lighting circuit the PSU is on..

 

[davesparks]

I just... Can't believe that. He must surely mean the elv circuit on the secondary side of the PSU. not the entire lighting circuit the PSU is on..

I may have misunderstood completely but what I got from the first post is that he wants a 12V lighting circuit, doesn't want to use an inverter, wants to keep the existing transformers/drivers in place and use a diode to prevent the 240V AC getting to the battery.

 

[Richard Williams]

I got a headache reading that lot

 

[DPG]

I bet the novelty of swapping batteries between house and van every day soon wears off.

 

[PJElectricalSW]

Just use a 12vDC to 230vAC inverter, no worries about any DC volt drop, LED gubbins and secondary lighting circuits. Use existing cabling with a switch over rotary switch to go from 'mains supply' or from the invertor supplied juice.

Economy 7 users do not know what they are sitting on...

 

[Deuce]

Just use a 12vDC to 230vAC inverter, no worries about any DC volt drop, LED gubbins and secondary lighting circuits. Use existing cabling with a switch over rotary switch to go from 'mains supply' or from the invertor supplied juice.

Economy 7 users do not know what they are sitting on...

So this is where we're at.. the op is gonna drive his 12v DC van to power an inverter to charge a 230ac battery to then power 230ac psu's to power 12v DC lights?

This has reached insanity level. I invite the op to post again and let us all know what the hell their motivation is! I can only assume it's stealing power... Which is fine, I don't care - on the basis that in this case stealing the power seems to be at least as much effort as earning it legitimately

 

[12vshocker]

To carify I will be using an inverter of some sort, but how do I get it to switch over automatically to mains supply if the voltage drops?