12V accessory power source

[Tstx92]

I'm adding a dual USB port with voltage reading to my 100 series. It will be mounted right near the radio and AC controls. I'm wondering where the best place to tap into is, without impacting the existing outlets or the cig lighter. For all intents and purposes of this application, the rig is stock. No dual batteries (yet), no fuse blocks (yet).
Would you run directly to the battery (seems like overkill but may provide the most accurate voltage reading)?
Tap into the kick panel or engine bay fuse box with an add a fuse?
Is there another accessory that you would recommend?
Thanks!

I tried using the search function but all of the results I found applied to replacing existing outlets or had to do with adding fuse blocks. @Trunk Monkey, your proving me wrong is welcomed.

-Ted

 

[nukegoat]

Why not just tap into the same lines as the cig or 12v outlets? USB current draw will be stupid low

 

[Tstx92]

Why not just tap into the same lines as the cig or 12v outlets? USB current draw will be stupid low

Would I then need to give it a larger fuse to account for the increased draw? Or is it really that low that the change would be negligible?

 

[nukegoat]

Would I then need to give it a larger fuse to account for the increased draw? Or is it really that low that the change would be negligible?

Negligible for all intents and purposes

 

[Tstx92]

Negligible for all intents and purposes

That makes my job easy. Thanks amigo!

 

[Mangocruiser]

Would I then need to give it a larger fuse to account for the increased draw? Or is it really that low that the change would be negligible?

15 Amp fuses on the Cig Lighter and 12V outlet, most you would draw from a single USB is 2,1 Amp, or 4.2 Amps if running dual USBs, cig Lighter generally draws around 10 Amps. You shouldn't need to change your fuse.

 

[reznunt]

Would you run directly to the battery (seems like overkill but may provide the most accurate voltage reading)?

I noticed a 0.1V difference between the readings when running the leads to the battery vs. a nearby source.

 

[nukegoat]

15 Amp fuses on the Cig Lighter and 12V outlet, most you would draw from a single USB is 2,1 Amp, or 4.2 Amps if running dual USBs, cig Lighter generally draws around 10 Amps. You shouldn't need to change your fuse.

Those amp ratings are at even lower voltage (5v is the USB standard). The power conversion isn't 100% efficient but it's even less than you think.

 

[Mangocruiser]

Those amp ratings are at even lower voltage (5v is the USB standard). The power conversion isn't 100% efficient but it's even less than you think.

Yep you are correct, also the battery voltage will not be exactly 12V either. Technically its about 875mA at 12 V with 100% efficiency under full load for each USB terminal configured for 2.1 Amps. Ballpark figures in the original just to indicate that fuse replacement is really not necessary

 

[gregnash]

Yup... I did like @nukegoat said earlier and just replaced the "normal" cigarette lighter with a dual USB adapter in its place. Was maybe a 1/2 job and really took more time to remove the panel and figure out how to get the cig lighter part OUT than anything.

 

[J1000]

My USB goes to 4.8A

https://amzn.to/2Ns3vhJ

 

[gregnash]

My USB goes to 4.8A

https://amzn.to/2Ns3vhJ

Yup that is the same exact one that I got. Just other location as I wanted to keep the 120v plug for "just in case."

Untitled by Greg Fisicaro, on Flickr

 

[Stovations]

My USB goes to 4.8A

https://amzn.to/2Ns3vhJ

How did you wire this in? Can the factory wiring going the the factory 12v be used?

 

[J1000]

How did you wire this in? Can the factory wiring going the the factory 12v be used?

Yep, I used the power connection for that cigarette lighter to power the USB charger. Didn't even have to change the connectors. Super easy.