How To Hard Wire Mobius But Not To Fuse Box

[mkadam68]

Checking out the various recent How-To posts, it seems like everyone is wiring their dashcam off the fuse box. I'm thinking I don't need to, but...

OK, background first. 2008 Dodge Ram 1500. I have two cigarette lighters in the dash, one ignition-only-on and the other always on, each connected to their own 20A fuse. I have taken out both cig lighters (don't smoke) and replaced with USB power ports (each with dual ports: 1A & 2.1A). These are wired to the previous wires right behind the dash, connected with some wire nuts and wrapped in electrical tape. (On a side note: should I use any other connectors to secure auto wires together? It works, but I didn't know if there's anything more auto-specific.)

I currently have my Mobius powered by my ignition-only-on USB port with a mini-USB cable hanging down but wish to hardwire it behind the dash for that "clean" look.

This is where I enter unknown territory. I previously tried this, using the same hardwire kit that I currently have by connecting to the wires behind the dash. Just adding them into the wire nut and extending the circuit. But, when I turned on the ignition, it blew the circuit, blowing apart the 12v --> 5v converter and killing the USB port. The fuse in the fuse box and my Mobius were fine (thank God).

So then, this raises my question: am I doing it incorrectly? The USB port draws 2.1A, the Mobius maybe 2A when recording. Why would my 20A circuit go kerplouey?

Thanks for any help.

 

[niko]

CI previously tried this, using the same hardwire kit that I currently have by connecting to the wires behind the dash. Just adding them into the wire nut and extending the circuit. But, when I turned on the ignition, it blew the circuit, blowing apart the 12v --> 5v converter and killing the USB port.

Can you share some photos on how and where exactly did you connect converter ?

 

[mkadam68]

It was this hardwire kit (picture from the vendor). The converter came already installed/assembled. The only difference to mine was mine had no inline fuse as in this picture.

 

[KlueBat]

One of two things happened:

• You shorted something out when splicing in the hardwire power supply
• The power supply has an internal short

For the former just double check your connections. Makes sure that there are no exposed wires grounding out. Especially on the positive (+) side.

For the latter, try a different power supply. I just installed this one in my F150 and I love it.

 

[Ralph2]

Just speculation.. When you wired your USB gadget you would have cut the two wires originally supplying your cig lighter. One wire was hot.. the other ground. Now.. when you added your camera.. did you inadvertently mix up the hot and ground? Reverse feeding your camera could have been responsible for the "oops"

 

[SawMaster]

Ditto the above. You had something wrong for a fuse to blow.

The best electrical wire connection is soldering, but not everyone has that option. For automotive work, most folks use crimp sleeves which do very well as a permanent connection when used correctly. Problems arise when undercrimped, overcrimped, or crimped in the wrong spot. Watch for those and you'll do fine.Never use the "scotch-lock" type connectors which slip over an existing wire and add another to it. There's not much metal making contact, you can unknowingly cut some of the conductors or not pierce all of the insulation, they are'nt mechanically strong, and the covers teng to pop open in time exposing a 'hot' point which can short out. They barely work to start with and get worse from there.

Wire nuts aren't rated or recommended for automotive applications. That doesn't mean they can't be used successfully here- I've been using them for semi-permanent connections for decades without a single failure. The keys are to pre-twist the wires, trim evenly to a length very slightly more than what will go into the metal part of the connector, then twist up very tightly to protect against vibration. Taping up needs care too; go clockwise from the connector toward the wire to prevent unscrewing and use plenty so the tape will never be rubbed through. Stretch the tape a little doing this, leaving a couple inches of it unstretched for ending the wrap so it doesn't tend to unravel and you'll be fine. Never use them where high heat or oil may get to the connection, but it works great behind the dash or elsewhere inside.

Pbil

 

[mkadam68]

Just speculation.. When you wired your USB gadget you would have cut the two wires originally supplying your cig lighter. One wire was hot.. the other ground. Now.. when you added your camera.. did you inadvertently mix up the hot and ground? Reverse feeding your camera could have been responsible for the "oops"

The thought had occurred to me... I'll give it a try again in a bit.

 

[mkadam68]

Ditto the above. You had something wrong for a fuse to blow.

The best electrical wire connection is soldering, but not everyone has that option. For automotive work, most folks use crimp sleeves which do very well as a permanent connection when used correctly. Problems arise when undercrimped, overcrimped, or crimped in the wrong spot. Watch for those and you'll do fine.Never use the "scotch-lock" type connectors which slip over an existing wire and add another to it. There's not much metal making contact, you can unknowingly cut some of the conductors or not pierce all of the insulation, they are'nt mechanically strong, and the covers teng to pop open in time exposing a 'hot' point which can short out. They barely work to start with and get worse from there.

Wire nuts aren't rated or recommended for automotive applications. That doesn't mean they can't be used successfully here- I've been using them for semi-permanent connections for decades without a single failure. The keys are to pre-twist the wires, trim evenly to a length very slightly more than what will go into the metal part of the connector, then twist up very tightly to protect against vibration. Taping up needs care too; go clockwise from the connector toward the wire to prevent unscrewing and use plenty so the tape will never be rubbed through. Stretch the tape a little doing this, leaving a couple inches of it unstretched for ending the wrap so it doesn't tend to unravel and you'll be fine. Never use them where high heat or oil may get to the connection, but it works great behind the dash or elsewhere inside.

Pbil

Thanks for the info. (I have a handyman background around houses, but nothing with automobiles.)