I have just discovered a 12v cigarette type socket in the back of my car. It would be immensely useful for me to be able to charge a few mobile devices from it when I’m away at weekends (mobile phones, camera batteries, GPS etc), since I often leave straight after work and haven’t had time/remembered to charge everything I need.

I know I could just use a 12v cigarette plug with USB connection at the back, but it would be easier to just plug everything in together for the journey (often only 2 hours).

Inverters seem to range from £30 to £500.

What do I need? Ideally I’d be looking for one which has a couple of normal 240v plug sockets, or one socket which could take the load of a separate gang socket with a few mobiles attached to it.

Also, would it be capable of charging a Macbook occasionally too?

Use the 12v as much as possible. You can get multi socket adapters for cigarette lighter sockets. That’ll take care of most devices, especially if you get one with usb. Should be able to get a 12v charger for the macbook, PC ones are readily available. That’s what I do. The only thing I don’t have a 12v charger for is cameras so that runs off a small (150w) inverter which was £25 from maplin.

http://www.maplin.co.uk/150w-12v-inverter-with-usb-charge-socket-392915
http://www.maplin.co.uk/12v-triple-socket-adaptor-with-usb-charging-socket-224815
http://www.maplin.co.uk/150w-laptop-car-adaptor-223723

yep id go down the 12volt route as well for most of what you list.

when i really need 240 i have a jump start battery pack from halfords with an inverter built in that i pack and provides quite a length of power without worrying about my van starting again 😀

Sorry if this is a daft question, but does that mean I can buy a 12v cigarette plug with multiple USB ports and can charge multiple devices via USB at once (i.e. without the need for an inverter or anything else?)

edit: just saw the maplin links you added, those look great and answer my question. thanks! 🙂

Yes, anything that charges from USB can be put in multiple cigarette lighter socket. Check it’s on when the car keys are out though. Plugs range from 50p to one million dollars if it has an apple logo on it….

Any non usb charging devices need an inverter. There are some belkin laptop ones or general ones. I got mine from halfords it was a Watt rating but also has layman pictures of what you can use it for – camera/laptop/power tools

They can get warm so keep an eye on that. Also the inverter will draw lots more power if your charging lots of things so watch the battery. Best done while driving.

Just be aware that some things (like an iPad for example) draw more than the standard USB 500mA.

You can also get 12v chargers which will plug into the fag lighter socket for many laptops.

e.g. Apple

So there are many ways to avoid using an inverter

geoff, could you please post a link for the multi adaptor in the picture you posted?

thanks

http://www.amazon.co.uk/s/ref=nb_sb_noss_2?url=search-alias%3Delectronics&field-keywords=12v+twin+usb&x=0&y=0

and

http://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=m570.l2736&_nkw=car+usb+

The Griffin looks good for a USB only option and could be combined with a double or triple socket to increase options

http://www.ebay.co.uk/itm/GRIFFIN-POWERJOLT-TWIN-USB-Dual-USB-Car-Charger-for-iPhone-iPod-HTC-/140768463407?pt=UK_Mobiles_Accessories_RL&hash=item20c6744a2f

thanks, geoff 🙂

what they say makes no sense to convert 12 volt to 240 volt to then charge at 5 volt it is just wastefull

Check the fuse rating for the socket – probably only 10 amps- and dont overload

I have a Belkin inverter from Amazon, cost about £15.
It plugs into the cigarette lighter on one end and it has a standard plug socket on the other.
I plug an extension lead into it and the kids charge their phones, ipad, laptops, dvd players etc when we are on a journey.

It will not charge hair straightners though 🙁

I use a £30 inverter made by Ring and bought in Tescos.
Used it to charge rechargeable batteries, cameras and phones.

I have one of these. http://www.tantronics.co.uk/acatalog/Ring_E_Can_12V_240V_150W_Inverter.html

Got it from 7DayShop but they don’t seem to have them now.

Works well for battery chargers etc including iPad – doesn’t seem to have enough juice for my Macbook Pro.

Just a word of warning if you go down the 240v inverter router rather than 12v adapters. The cheaper inverters don’t produce ‘real’ sine wave outputs but rather a funny steppy shape instead. This can confuse some electronic devices such that they won’t work correctly but you can’t really tell which in advance. If you do want to go for an inverter then get one that produces true sine output rather than ‘modified’. These will unfortunately be more expensive. The device that grum linked to for example says that it won’t work for all chargers but you won’t be able to tell in advance which ones won’t work 🙁

leffeboy – is there a risk of damaging stuff or will it just not work? So far camera battery charger, AA battery charger, USB charger for a bluetooth speaker, and an iPad charger seem to be fine.

Just the MB Pro that doesn’t work properly – it starts charging then stops again.

Just the MB Pro that doesn’t work properly – it starts charging then stops again.

http://www.ebay.co.uk/itm/NEW-APPLE-MACBOOK-MACBOOK-PRO-13-15-17-85W-12V-CAR-ADAPTER-CHARGER-/150703956182?pt=UK_Computing_LaptopAccessories_PowerSupplies&hash=item2316a7e0d6

leffeboy – is there a risk of damaging stuff or will it just not work?

It’s impossible to tell really unfortunately. My experience (and yours) is that they either work or don’t. Also, when they don’t they often just blow a fuse and that’s it. However, as an electronics engineer who has built a couple of these things into some products I can see there is a possibility to confuse the device that is plugged into them (eg. The MacBook charger) and upset the output. I wouldn’t then expect that to damage the device (MacBook in this case) as it would have some protection but you never know. This is the problem of having a bit too much knowledge really.

The upshot is if I have to use an inverter I try not to use cheap ones but I don’t recall any of our stuff dying in the last 8 years due to inverters so I wouldn’t worry.

Most work fine, some more modern switch mode power supplies get a bit uppity but almost universally they’ll just refuse to work if they are not happy. You could damage the inverter with the wrong load so be wary of using motors or inductive loads on an inverter). However it makes no sense to do 12DC>240AC>5DC so stick with a simple quality DC-DC.

You are all taking 12 volts DC upping it to 240 v AC in order to step it back down to lower than 12 volts DC in order to charge low voltage stuff…madness…almost nothing on here mentioned for charging is over 12 volts.

Just get proper 12 volt stuff with voltage adapters and ends for what you need

Junkyard – Member

You are all taking 12 volts DC upping it to 240 v AC in order to step it back down to lower than 12 volts DC in order to charge low voltage stuff…madness…almost nothing on here mentioned for charging is over 12 volts.

😐

I’m really very sorry for my awful inefficiency JY! 🙂

But doesn’t doing what you suggest mean having to buy lots of different 12v chargers for everything, rather than just the one device? Or am I misunderstanding?

Is there anything of any great import that won’t charge off a USB port these days?

http://www.amazon.co.uk/Griffin-GC23089-PowerJolt-Universal-Charger/dp/B004Z4MDGG

I’ve with Junkyard here, buying an 240V AC inverter to charge a 5V DC device from a 12V DC supply is lunacy of the highest order.

Is there anything of any great import that won’t charge off a USB port these days?

Neither my camera battery charger nor my aa battery charger (the main reasons I got the inverter) do.

I’ve with Junkyard here, buying an 240V AC inverter to charge a 5V DC device from a 12V DC supply is lunacy of the highest order.

OK physics nerds – it’s lunacy of the highest order apart from the fact that it didn’t cost much (about £20 IIRC) and it works fine.

Neither my camera battery charger nor my aa battery charger (the main reasons I got the inverter) do.

*coughs*

http://www.amazon.co.uk/PowerPlanet-Battery-Travel-Europe-Charger/dp/B003VKTJN0/ref=sr_1_1?ie=UTF8&qid=1343069925&sr=8-1

http://www.amazon.co.uk/7dayshop-AAA-Battery-Charger-batteries/dp/B002IW5LYI/ref=sr_1_2?s=electronics&ie=UTF8&qid=1343069971&sr=1-2

camera battery charger

‘s a good point actually. Both of my camera chargers are mains powered too. Changing that would require a replacement charger.

it works fine.

Sure, but it’s not particularly efficient. A percentage of the car battery’s capacity will be lost as heat rather than used as charge, for a start. So, it’ll flatten the battery faster. And it’s a double whammy here, because you’re losing energy converting DC > AC, then again converting straight back to DC again. Modern chargers can be a lot more efficient than they used to be, but still.

In the case of the camera charger there’s not a lot of choice (EDIT – or may be, just seen the previous post). Where you have got a choice, a DC > DC adapter is always going to be preferable to running through an inverter.

Thanks geoffj – still means having several different chargers cluttering up my car though (rather than just taking the ones I already have).

OK nerds – so what kind of percentage energy loss through the pointless conversion are we talking here? I want real numbers. 😉

“Geeks” is the term you’re looking for.

Depends on the devices. I’ve seen figures of 90% efficiency quoted for high-end inverters. Newer switched-mode chargers are considerably better than the old linear chargers, charging relatively intelligently rather than quietly boiling themselves.

I don’t have figures to hand, but pulling them out of the air I’d guess with high quality components you’re maybe looking at about 80% of your battery charge actually being used to charge your devices. With cheap electronics though who knows, 20%?

Not really my forte TBH, I’ve a basic electrical knowledge but I’m no expert. Maybe someone else can give you a more definitive answer here.

80-90% isn’t a bad figure but that is for when the device is near maximum load. When you aren’t taking much power out the figure will drop lower as there is standby power and losses. So at almost no power out you could go down to 20% efficiency

very wet finger in air numbers