Inverter Question

Macy0161

We're running out of 12v sockets when travelling between phones, and multiple tablets etc., so I am thinking of getting a small inverter (such as this: http://www.maplin.co.uk/p/12v-modified-sinewave-230v-mini-inverter-with-5v-usb-a76kc ).

I'm working out the tablet chargers at 10W each, less for a phone charger. It'd usually be two at a time.

So my question for the electrical experts is: can I run a normal bog standard multi socket extension lead from this and run a couple of tablet charges and maybe a mini dvd from it? Or am I missing something, which could be quite likely? It would mainly be for when we're on the move, but if I had it, I'd use it hook up or not.

I know it'd be more efficient running direct from the 12v, but it's a lot messier with wires across the walk way etc. I could set this up and the chaps could, quite literally, be left to their own devices!

moodrater

Can't see that inverter + extension lead + wall warts + cables is better than something like this:

http://www.ebay.co.uk/itm/Saicoo-8A-40W-5-USB-High-output-Ports-Car-Charger-85CM-Cable-Length-with-sepa-/191278438470?pt=UK_MobilePhones_MobilePhoneAccessories_MobilePhoneChargers&hash=item2c89155846
http://www.amazon.co.uk/AVANTEK-Intelligent-Charger-Charging-Computers/dp/B00L34ARD2/ref=sr_1_10?ie=UTF8&qid=1407500504&sr=8-10&keywords=5+port+usb+car

Also worth considering:
http://www.boards.ie/vbulletin/showthread.php?p=91225868

Macy0161

For where I'd want to set it up, that'd still need an 12v to 12v extension lead - all the 12v sockets are the opposite side to the diner/ travel seats, in a brilliant design move by LMC! The diner/ travel seats are behind the cab on one side, with a 12v socket behind the cab on the opposite, so any solution involves a cable going from there over, behind the cab seats.

I could go for a single 12v input, to a double output, but then rather than the stock chargers, I'd be getting into in car chargers.

Ignoring aesthetics/ hassle/ cable runs - is there a technical issue as to why I couldn't run 12v --> inverter --> multi socket extension lead, once I don't go over capacity?

That Maplins jobbie looks nasty. Think of the weight and leverage on the socket with that thing plugged in, then another wall-wart plugged into it.
You'll end up with something melted when it vibrates loose and starts arcing.

There's a few ways to run this; the cleanest is to stick an inverter beside your leisure batteries and use a double pole double throw 250v relay with the coil wired to the mains live that changes over the mains sockets in the van to double as inverter sockets on the move.

Next up is keep it 12v; go to a large electrical wholesalers and get 2 x 13mm² stranded conductors (black and red, 1.5% voltage drop on 10Amps over 7 metres) and run them from the leisure batteries under carpet or otherwise discretely to ceramic cig. lighter/USB socket jobbies rated for 10A. This may involve soldering as most cig. lighter sockets are under-wired and you'll be removing the provided cable for your own.

Otherwise you can; again put the inverter beside the batteries and run standard domestic 1.5mm² 3 core cable to dedicated inverter sockets where you'd like them running from the inverted AC output.

The inverter should be hard wired to the battery clamps of the leisure bank (forget about croc. clips and cig. lighter plugs they've dreadful CSA and they'll shake loose. Preferably fused on the AC and DC sides. Or use circuit breakers (MCBs) if you want to get fancy. You can use the mains MCB with the changeover relay if you wire it correctly.

I'd consider at least a 150W inverter too.

Either way you might want to consider running new cable permanently to where you want the sockets.

Macy0161

Macy0161 wrote: »

Ignoring aesthetics/ hassle/ cable runs - is there a technical issue as to why I couldn't run 12v --> inverter --> multi socket extension lead, once I don't go over capacity?

Capacity is rated for max heat dissipation. Better off compensating for voltage drop or keeping the 12v side of things as close to the batteries as possible.

Most appliances will run happily on a slightly reduced voltage. Switching regulators will be much more efficient if the output of the socket is the same as the battery posts.

Voltage drop isn't an issue for your purposes on the AC side of things so for this you can stick to normal cable ratings. It won't make any difference to the USB ports (5v outlets) either.

Sir Liamalot

Sir Liamalot wrote: »

...the cleanest is to stick an inverter beside your leisure batteries and use a double pole double throw 250v relay with the coil wired to the mains live that changes over the mains sockets in the van to double as inverter sockets on the move.

Something like this except you can ignore the Galvanic isolator (it's a boat thing) and the non inverter loads.





Here's one that utilises the same MCB for mains and inverter but the relay has double the connections you need due to the presence of non-inverter loads.


So it's a cross between the two (linky) sorry if that's confusing...I'm just being lazy. I can post a specific schematic if you're interested.

If you are hard wiring the inverter and you're a pedant over mA like me, you may want a switch or polarity indiscriminate DC MCB on the DC side. My Maplins 600W MSW still uses current keeping the built in capacitors charged with the output switched off.

Actually thinking about it; there's not much point in running the inverter and mains through the same MCB because for your application there's a rather large mismatch in ratings (≥10A on mains and 0.75A on a 150W inverter).

Strictly speaking the MCB protects the cable not the appliances so there's nothing wrong with it, but the job can be done neater with the fuse in the plug that lives in the inverter output or the inverter internal protection (if it has any). Leave it with me for a few hours and I'll post a diagram.

niloc1951

Here's a simple way to power all the sockets directly from an inverter.
Disconnect the socket feed circuit from the output of the MCB and put a 13amp plug on the end of the wire.
Fix a new 13amp socket close by the inverter and connect it directly to the output of the MCB, in place of the feed to the original sockets.

When on EHU plug the cable going to the original sockets into the new socket wired into the MCB, all sockets will now be live from the mains supply.

When not on EHU plug the cable going to the original sockets into the inverter, all socket will now be live from the inverter when it is switched on.

If the above is beyond your competence with mains power a friendly electrician might oblige.

Remember the total load on the sockets will have to be within the capability of the inverter, but when on mains they can be used as normal.

You just gave me an idea Niloc...if you want a cowboy solution ya could just connect the inverter to the batteries and run a 13A plug from it to a 16A socket through a window outside into your EHU hook-up point.
Wiring diagram will be another while...just got my air compressor back up and kicking

Macy0161

Thanks for the replies and taking the time and saving me from a bodge job . unfortunately, the proper solutions are above my competence, and it's not enough of an issue to pay someone competent to do it. But thanks again!

No worries, I had this drawn anyways before I saw the reply. Here's how I would do it. Once it's in it'll self-select with priority to mains and you don't have to worry about it. You'd want a multimeter and a bittov know-how to get it together, or a sparky inclined mate you could bribe with pints. It's an easy enough job.



Short of that then this might suffice with yer bog standard plug-boards
http://www.maplin.co.uk/p/nikkai-12v-modified-sinewave-150w-inverter-with-usb-charging-socket-a00jz



I still don't like the cig. lighter plug but at least this one is light in the socket and should hold ok. Just feel it and see if it's getting hot after a while in use, if it's not Bob's yer Uncle.
I'd want to hard-wire it on better cable but you'd have to butcher it and find and mark the polarity so maybe best left as is.
Looks like you have to go to 300W or a different store for croc. leads.