Reddit reviews New Practical 12V 120W Car Motorbike Motorcycle Boat Tractor Cigarette Lighter Power Outlet Plug Socket

Except for the driving faster, the rest should be relatively easy.

• Cup Holder: My wife likes the Ram Mount products for her cup holder. She uses the cup holder connected to a 6" double socket arm and attached to her chair unitrack with a diamond plate with a 1" ball.
  
  
• Power Socket: We basically bought one of these female outlet plugs but we got it from our local harware store. Her wheelchair technician hooked it up in about 10 minutes when she was in for a different repair. Although we did add a 3 amp fuse in the wiring to be sure not to damage her chair (or use anything that draws too much power)...this was almost 10 years ago and it was the first one he did, so wanted to be careful. Again it was just attached into her unitrack to hold in position. She then uses various standard car chargers depending on what she is doing.
  
  
• LED lights...we haven't done anything permanently (but have had some temporaries that plug into her power socket). But pretty much any type of LED and switch should be easily wireable into your battery.

Well the good news is that, if your DVD player is powered by 12V (and I fail to see why it wouldn't, the internals are already DC so for GM to put in a 12V DC to 110V AC to ??V DC is wasteful maddness) a cigarette lighter to USB adapter is literally just a 12V to 5V transformer. But I'd check with a voltmeter first. Or you could dismantle the 12V to usb plug and wire it directly to the car.

You could wire up one of these and plug in this, and your pi can be powered.

However, I have no clue what that car screen uses to connect to the DVD player, you might get lucky and its RCA, but I'm doubtful.

This is not a project for beginners.

> What do you mean relay switched with the ignition?

I have a relay wired up directly to the battery using the headlight line as the switch. So when the headlight is on (ignition is on), the relay closes and gives me power that comes direct from the battery, fused. When the ignition is off, relay is open and there's no power draw.

> They didn't have any regulators at the store so I opted for a diy cigarette lighter socket. Got a 12ga 30A fuse holder (they didn't have anything else) and a 10A fuse, plus a USB car charger.

A cigarette lighter socket is a good idea anyway, I also have one of those wired up to the bike as well. I have my cigarette lighter ignition-switched the same way. I don't want to accidentally leave something plugged in and have it kill my battery! It doesn't take much to kill a bike battery, after all.

> Am I all set or do I need anything else? should I wire everything with 12ga wire? after coming home, I realized I only have 22ga wire... is that enough?

I would say it's better to be safe than sorry! 22ga is too small. Here's a rule-of-thumb chart: http://www.powerstream.com/Wire_Size.htm It says there that 22ga is good for 0.92A and 12ga is good for 9.3A.

Realistically, you won't even be drawing 9A if you're just using the cigarette lighter for a USB charger. A typical smartphone draws 1A. So lets assume 3A in case you get one of those dual-port things. 3A at 5V is 15W. 15W at 12V is only 1.25A. Always good to have some margin of error (those adapters aren't 100% efficient, of course), so lets say more like 3A. On the chart, that puts you at around 16ga. You could MAYBE be ok with 18, but I wouldn't go any smaller than that. 12 or 14 would be good and safe.

Now, the second part of this is your fuse selection. It's SUPER important to pick the right size fuse! If you have wire that can carry 3A and a 10A fuse, the wire is going to melt before the fuse pops. That's bad. I think my cigarette lighter is wired up with a 3A fuse, because I planned to never plug in anything that draws more than that. The cigarette lighter in a car usually has a 20-30A fuse and you can plug a portable fridge or air compressor into it, but that's not likely to work so well on a bike. I know my bike isn't producing 30A extra unless I turn the headlights off.

You can get kits that come with the plug, wires, and inline fuse for pretty cheap:

http://www.amazon.com/Practical-Motorbike-Motorcycle-Tractor-Cigarette/dp/B00E963JFY/ref=sr_1_4?s=automotive&ie=UTF8&qid=1397856641&sr=1-4&keywords=cigarette+lighter+kit#productDetails

http://www.amazon.com/Motorcycle-Cigarette-Lighter-Outlet-Socket/dp/B007BIUKLI/ref=sr_1_3?s=automotive&ie=UTF8&qid=1397856719&sr=1-3&keywords=cigarette+lighter+kit+motorcycle

Personally, I'm a fan of the waterproof ones with a spring-close lid, because I know the one time I forget to close the rubber lid it will rain into my cigarette lighter port!

EDIT to add: you can also get some kits that go directly from 12V to a USB port at 5V, but I've found that those don't work particularly well with all devices. Because Apple and Android devices need different USB port configurations to charge at full-rate, I decided I was better off using my own adapter.