DC appliances

[Thunder Dan]

I'm looking at those Renogy kits and I understand that you use an inverter to power your things on AC. But suppose you have some items that have DC cords that plug into cigarette lighters. Is there something to connect them to the house batteries? Also, is there any advantage to using things with DC over AC? Thanks for looking, I'm totally new and still trying to figure things out.

 

[MrNoodly]

"But suppose you have some items that have DC cords that plug into cigarette lighters. Is there something to connect them to the house batteries?"
You can wire 12V DC outlets (found at auto parts stores, Walmart, RV supply places, etc.) directly to your battery/batteries.

"Also, is there any advantage to using things with DC over AC?"
Inverters consume some of your power. Chargers for things like laptops and phones convert AC to DC, because most people live in buildings. But it's silly and inefficient to go from DC (your house batteries) to AC (via the inverter) only to take it back to DC via the charger. So for my laptop, I got a DC-to-DC charger (eBay). And for the phone I have one of those USB plugs that fit in DC outlets. So, if you can find 12V DC small appliances, sure, go for it.

 

[Optimistic Paranoid]

"But suppose you have some items that have DC cords that plug into cigarette lighters. Is there something to connect them to the house batteries?"
You can wire 12V DC outlets (found at auto parts stores, Walmart, RV supply places, etc.) directly to your battery/batteries.

It should be understood that these things were originally designed as cigarette lighters at a time when everybody and their kid brother smoked.  They were adapted as power plugs because they were already there, but they are not a particularly GOOD design as power plugs.

It should also be understood that the majority of the ones sold at parts stores, Walmart, RV supply places, etc. are cheap foreign crap that really don't work well or stand up well over time.

The BEST ones are the ones you get from the boating world, such as the Blue Sea Marine brand, available for order through Amazon, as well as at boat supply places.

Regards
John

 

[WheelEstate USA]

We just bought a 19" TV from Best Buy ($90) that has an AC wall brick that transforms that to 12V.
I snipped off the brick and wired it into my 12V house system.
Guess what?....The amplifier for the antenna is 12V too. Snip goes another AC wall wart and reason not to use the inverter.

Ya gotta be careful of polarity (+ and -) and a fuse.

Amazon has a ciggy plug/cord if you wanna go that route with the TV.....
http://www.amazon.com/gp/aw/d/B008Y...lt+tv+cord&dpPl=1&dpID=31wVBe+6s1L&ref=plSrch

I haven't found a proper cord for the antenna amp but its easy to snip and install a 12V plug on the wire.

 

[Thunder Dan]

We just bought a 19" TV from Best Buy ($90) that has an AC wall brick that transforms that to 12V.
I snipped off the brick and wired it into my 12V house system.
Guess what?....The amplifier for the antenna is 12V too. Snip goes another AC wall wart and reason not to use the inverter.

Ya gotta be careful of polarity (+ and -) and a fuse.

Amazon has a ciggy plug/cord if you wanna go that route with the TV.....
http://www.amazon.com/gp/aw/d/B008Y...lt+tv+cord&dpPl=1&dpID=31wVBe+6s1L&ref=plSrch

I haven't found a proper cord for the antenna amp but its easy to snip and install a 12V plug on the wire.

When you wire it into your 12V system, do you mean you have the wires just connected directly to the battery?

 

[towhee]

Dan, it sounds like you are about where I was a year ago in understanding electricity and wiring. I got help from a vandweller (thanks again Fred!) installing a simple system involving one battery, a 100 watt portable from Renogy. I charged from solar and alternator and drew power through a cig lighter plug. It met my needs at the time.

Since then I have read a LOT and changed vans and done my own wiring. I have learned a lot.

I think the best learning is from seeing other peoples systems and talking to them about their choices. I couldn't do that as I was traveling alone.

Good learning also comes from living with a simple system for a while.

And then reading is essential but I would put it last. because a lot of what I read just swirled around inside my head until I actually saw and handled the things I had been reading about.

I highly recommend the Renogy suitcase, paired with a deep cycle battery and a cig lighter outlet it will get you on the road.

One last thought. Talk to lots of people about how DC systems work. Find that rare person who can teach what they know clearly enough to be followed by a novice like you or me.

 

[LeeRevell]

You can get lead battery post connectors with screw-on (threaded) terminals attached, to make hookups easier. Marine batteries and true deep cycle batteries have these threaded terminals already.  I generally connect a multi-post buss bar to the positive battery terminal, to prevent having a bunch of wires attached to the battery itself.  Each device wire should be fused.  Usually not hard to find a handy pass-thru in the firewall to the van interior.  Or drill a small hole in the doghouse.
I mount another buss bar for the grounds in the body of the van, for handy ground connection.  The BB is securely fastened to the FRAME, not the body of the vehicle.
For a house battery bank in the main body, the BB is close to the batteries for simplicity, then you can connect your good quality ciggy or better grade 12V plug to it.  Again make sure all devices are fused.  Good place for the inverter too, for those devices that do need AC power.
BMW makes a very good proprietary 12V plug and socket for motorcycle use.  Much more secure than the average box-store ciggy plug.

 

[WheelEstate USA]

Dan...Simple answer, yes, the TV and other 12V items are connected to the house battery(s), which are charged by Renogy solar on the roof. I do not charge them with the alternater, so nothing is grounded to the van frame.
As Lee said, buss bars and fuses are employed for ease and safety.

Once you get the hang of 12V its easy peezy.

 

[blars]

For 12v power connectors, I recommend Anderson Powerpole connectors. The 15A, 30A, and 45A versions mate with each other, and you choose which to use by the wire size. They cost about $1 per pair in quantity, (from US vendors on ebay) and the special crimper for them is about $35. There are videos of how to crimp them on utube, I recommend "#120: How to install anderson powerpole connectors".

 

[BradKW]

Ya gotta be careful of polarity (+ and -) and a fuse.

When you cut a plug or wall wart from a device, how does one determine which is the pos/neg wire?

 

[LeeRevell]

This should make it clear as....  mud.  Best thing is to look at the symbol on the device, or meter it out with a  multimeter.

http://electronics.stackexchange.co...ch-end-of-a-barrel-connector-is-positive?rq=1

 

[BradKW]

This should make it clear as....  mud.  Best thing is to look at the symbol on the device, or meter it out with a  multimeter.

http://electronics.stackexchange.co...ch-end-of-a-barrel-connector-is-positive?rq=1

Wow, that is surprising just how unclear the answer is. So. I'm not very adept with a multimeter...on occations I've used one, I hook it up and then spin the selector until it reads some approximation of what I think it should be reading, call it a qualified success and move on. Trying to figure out how to use one to determine polarity in a situation like this, I imagine it would go something like this? :

1) prior to snipping, separate the strands
2) mark the individual strands with tape or marker (does DC devices have a 3rd ground wire?)
3) snip the wires, cutting the "mark" in half so its clear which is which.
4) power up the "plug" end so snipped ends are live.
5) use multimeter to determine positive (if needle goes up its correct, if needle tries to go negative its reversed?)
6) transfer finding to device cord and hook up to 12v panel.

I'm assuming there's no way to tell polarity unless power is supplied, meaning you can't test the device itself once cord is cut?

thanks!

 

[SternWake]

One of 2 of the wire's insulation will either have a stripe or some ridges on it.

If there is a barrel type connector the outside part is almost always the (-)

Set a digital multimeter to ohms. Place one DMM probe on outside of the barrell connector(-) and place other probe on either stripped wire end. When the DMM goes from 1 to 0 or near zero, you have found the (-) wire. Take note whether it is the wire with the stripe or the ridges.

You can also cut and strip the wires and then plug in the wall wart, then use DC voltage setting on the DMM with probes on the stripped copper and see whether it reads 12v+ or Negative, and determine the polarity.

Just make sure the copper does not touch when the wall wart is plugged in.

 

[WheelEstate USA]

I plug in and test with the multimeter. My meter tells me if I have a wrong wire.
Often the wart will show a symbol as to whether the tip is pos or neg.

 

[WheelEstate USA]

You got it Brad

 

[rvpopeye]

Parents of Bindi .
What brand TV and Antenna did you buy ?
I was looking for that 12v wall wart and couldn't find any when I was shopping last spring and ended up with a Vizio TV that was on sale (regular AC plug) and a ?? brand antenna with a 6 volt wart. Maybe next time.

 

[WheelEstate USA]

The TV is an Insignia 19" from Best Buy. 
The antenna is an RCA ($39) from Wally's.

 

[LeeRevell]

Upshot of the link I had and others I read is, there is NO standard.  Best to meter it to make sure.