Reply
 
Thread Tools Display Modes
 
Old 02-13-2019, 05:35 PM   #1
Platinum Member
 
rowiebowie's Avatar
 
Join Date: Jul 2018
Location: Texas
Posts: 1,102
Default 12v thru Cat5 Cable-Harebrained Idea?

I have a disconnected Cat5 cable (previously used to power the now disconnected Sunexplorer solar monitor) that runs from the power side of my Avenue to the other side where I'd like to install a USB charger outlet.

I really don't want to "do it right" and try run new wires across the van to the opposite side because the difficulty just wouldn't be worth it in my opinion. Would the 8 wires within the old Cat5 (ethernet) cable provide the 2.4A required to power the USB outlet?

If so, how would I wire it since the 8 wires are individually insulated? 4 for positive & 4 for negative? All 8 positive and find a separate ground?

If this is the most stupid post you've ever seen, you can tell me. I'll only cry a little bit.
.
__________________

rowiebowie is offline   Reply With Quote
Old 02-13-2019, 06:45 PM   #2
Platinum Member
 
markopolo's Avatar
 
Join Date: Oct 2006
Location: New Brunswick, Canada
Posts: 7,850
Default

Is it a single 2.4A 5V USB outlet? How long will the wire run be? Can you see what AWG is marked on the individual wires?

I took a quick look at a couple of parallel conductor calculators and both indicate 4 x 24AWG in parallel would equal approximately 18AWG which would seem to be fine.

Maybe see if anyone else here has an opinion on the idea.
__________________

__________________
Two bikes on sliding cargo box: https://www.classbforum.com/forums/m...icture206.html & 1997 GMC Savana 6.5L Turbo Diesel Custom Camper Van Specifications: https://www.classbforum.com/forums/f...vana-5864.html
markopolo is offline   Reply With Quote
Old 02-13-2019, 07:04 PM   #3
Gold Member
 
Join Date: Sep 2014
Location: Missouri
Posts: 89
Default

It's not a stupid idea, but I'm not sure it will work in this case.

There are electrical standards for supplying Power Over Ethernet. The critical thing is not drawing too much current through those small wires. The "type 3" standard appears to be using two wires for the + side and two wires for the - side, with a maximum total current of 600mA per pair, or 1.2A total.

Your 2.4A USB charger is supplying 12W of power, which means at 12V it's drawing at least 1A (probably higher due to losses in the charger). That's pretty close to the limit. Before you go ahead, be sure to measure the current being drawn by your charger when it's under full load to make sure it isn't going over 1.2A.

I'm assuming here that your charger has a single outlet. If your charger has multiple 2.4A outlets, then the maximum current drawn will be too high. A dual 2.4A charger will be drawing at least 2A under full load, which would be well over the limit.

(The "type 4" standard allows for 960mA per pair, but the caveats about "temperature planning" makes me think that there are issues with heat, and an RV isn't really a temperature controlled environment.)
__________________
2003 Roadtrek 190 Popular
Gryphon is offline   Reply With Quote
Old 02-13-2019, 11:13 PM   #4
Platinum Member
 
Boxster1971's Avatar
 
Join Date: Mar 2012
Location: Maryland
Posts: 907
Default

Quote:
Originally Posted by rowiebowie View Post
I have a disconnected Cat5 cable (previously used to power the now disconnected Sunexplorer solar monitor) that runs from the power side of my Avenue to the other side where I'd like to install a USB charger outlet.

I really don't want to "do it right" and try run new wires across the van to the opposite side because the difficulty just wouldn't be worth it in my opinion. Would the 8 wires within the old Cat5 (ethernet) cable provide the 2.4A required to power the USB outlet?

If so, how would I wire it since the 8 wires are individually insulated? 4 for positive & 4 for negative? All 8 positive and find a separate ground?

If this is the most stupid post you've ever seen, you can tell me. I'll only cry a little bit.
.
I agree with Gryphon - not a stupid idea. But powering a USB outlet is likely too much for the fine wires in a Cat5 cable. I've used a abandoned Cat5 cable in my van to power a small LED indicator light, but it only draws 1.5mA. This is the LED I was powering...

https://www.bluesea.com/products/817...2_24V_DC_Green
__________________
2013 Airstream Interstate Lounge EXT on 2012 Sprinter 3500 170Ext
Formerly: 1973 Dodge B300 DIY pop-top conversion
Boxster1971 is offline   Reply With Quote
Old 02-13-2019, 11:48 PM   #5
Platinum Member
 
Join Date: Aug 2010
Location: Minnesota
Posts: 7,791
Default

According to the link in this discussion


https://electronics.stackexchange.co...-on-cat5-cable


you would be right on the edge for 24ga wire. .577 X 4 2.308 amps plus 4 wires in a bundle will run hotter than a single wire in air. I don't know what the temp rating on Cat 5 is, but maybe 90*C or even 75*.
booster is offline   Reply With Quote
Old 02-14-2019, 01:07 AM   #6
Platinum Member
 
rowiebowie's Avatar
 
Join Date: Jul 2018
Location: Texas
Posts: 1,102
Default

Quote:
Originally Posted by markopolo View Post
Is it a single 2.4A 5V USB outlet? How long will the wire run be? Can you see what AWG is marked on the individual wires?

I took a quick look at a couple of parallel conductor calculators and both indicate 4 x 24AWG in parallel would equal approximately 18AWG which would seem to be fine.

Maybe see if anyone else here has an opinion on the idea.
Sorry, should have provided more information in the beginning.

The outer sheathing states 26AWG wire. Although the USB outlet is just across the aisle, I estimate the length of wire to be maybe 12-15ft max in length as it appears to cross underneath from side to side.
.
rowiebowie is offline   Reply With Quote
Old 02-14-2019, 01:10 AM   #7
Platinum Member
 
rowiebowie's Avatar
 
Join Date: Jul 2018
Location: Texas
Posts: 1,102
Default

Quote:
Originally Posted by Gryphon View Post
It's not a stupid idea, but I'm not sure it will work in this case.

There are electrical standards for supplying Power Over Ethernet. The critical thing is not drawing too much current through those small wires. The "type 3" standard appears to be using two wires for the + side and two wires for the - side, with a maximum total current of 600mA per pair, or 1.2A total.

Your 2.4A USB charger is supplying 12W of power, which means at 12V it's drawing at least 1A (probably higher due to losses in the charger). That's pretty close to the limit. Before you go ahead, be sure to measure the current being drawn by your charger when it's under full load to make sure it isn't going over 1.2A.

I'm assuming here that your charger has a single outlet. If your charger has multiple 2.4A outlets, then the maximum current drawn will be too high. A dual 2.4A charger will be drawing at least 2A under full load, which would be well over the limit.

(The "type 4" standard allows for 960mA per pair, but the caveats about "temperature planning" makes me think that there are issues with heat, and an RV isn't really a temperature controlled environment.)
The outlet is a double 2.1A USB. But I can find a single for that outlet so it is not overloaded.
.
rowiebowie is offline   Reply With Quote
Old 02-14-2019, 01:16 AM   #8
Platinum Member
 
rowiebowie's Avatar
 
Join Date: Jul 2018
Location: Texas
Posts: 1,102
Default

Quote:
Originally Posted by Boxster1971 View Post
I agree with Gryphon - not a stupid idea. But powering a USB outlet is likely too much for the fine wires in a Cat5 cable. I've used a abandoned Cat5 cable in my van to power a small LED indicator light, but it only draws 1.5mA. This is the LED I was powering...

https://www.bluesea.com/products/817...2_24V_DC_Green
Your LED light is similar to one I wired earlier as an indicator for my battery disconnect to show when the battery is engaged. I agree it is very low draw compared to what I'd use the wiring for.

It's not a "need" but rather a "wish". I'm really just looking for something productive to do with the old Cat5, since the install of my new Victron 75/15 solar controller with bluetooth will make the old Sunexplorer monitor unnecessary.
.
rowiebowie is offline   Reply With Quote
Old 02-14-2019, 01:19 AM   #9
Platinum Member
 
rowiebowie's Avatar
 
Join Date: Jul 2018
Location: Texas
Posts: 1,102
Default

Quote:
Originally Posted by booster View Post
According to the link in this discussion


https://electronics.stackexchange.co...-on-cat5-cable


you would be right on the edge for 24ga wire. .577 X 4 2.308 amps plus 4 wires in a bundle will run hotter than a single wire in air. I don't know what the temp rating on Cat 5 is, but maybe 90*C or even 75*.

Turns out the cable sheath reads 26AWG and length is an estimated 12-15ft. So even combining wires is a no go? What about going down to a single 1A USB port?
.
rowiebowie is offline   Reply With Quote
Old 02-14-2019, 01:51 PM   #10
Platinum Member
 
markopolo's Avatar
 
Join Date: Oct 2006
Location: New Brunswick, Canada
Posts: 7,850
Default

All 8 x 26 AWG wires in parallel would give an effective AWG of 17 according to a calculator I looked at.

4 x 26 AWG wires in parallel would give an effective AWG of 20 according to the same online calculator. It comes down to your comfort level with using parallel wires. Is there a 12V wiring code to refer to?

Using 20AWG at 15' 1-way distance (30' round trip) with a 1 amp load results in only 1.64% voltage drop using this calculator https://www.powerstream.com/Wire_Size.htm . I don't know how much current at 12V a single 1 amp 5V USB outlet would use. We don't know the loss with the conversion. 1A at 5V = 5W 1A at 12V = 12W

Is there movement at both ends of the Cat5 cable if you pull on it? If so, maybe it could be used to pull new wires through.
__________________
Two bikes on sliding cargo box: https://www.classbforum.com/forums/m...icture206.html & 1997 GMC Savana 6.5L Turbo Diesel Custom Camper Van Specifications: https://www.classbforum.com/forums/f...vana-5864.html
markopolo is offline   Reply With Quote
Old 02-14-2019, 04:00 PM   #11
Platinum Member
 
rowiebowie's Avatar
 
Join Date: Jul 2018
Location: Texas
Posts: 1,102
Default

Quote:
Originally Posted by markopolo View Post
Is there movement at both ends of the Cat5 cable if you pull on it? If so, maybe it could be used to pull new wires through.
Ive pulled on the Cat5 (but I haven't pulled too hard yet) and it seems fixed in place. It could be just bundled and zip tied somewhere, but it could also be compressed behind a cabinet, so I don't believe it is a candidate for fishing a new wire in it's place. Darn tight spaces in a class b.
.
rowiebowie is offline   Reply With Quote
Old 02-14-2019, 07:58 PM   #12
New Member
 
Join Date: Feb 2019
Location: Pleasanton CA
Posts: 18
Default

A bit complicated, but if you use a 12 - 24 volt converter, push the power through at 24 volts to the other side, that doubles the power for a given current.

Blue sea makes some 24 volt in / USB outlets.

The downside is that since it is unlikely for that cat 5 wire to be inside of a protective sheath, if it wears through and shorts it wouldn't be ideal.

It might be cheaper and easier to buy one of those portable USB batteries that charge from an existing source and then power what you need.
__________________
Some experience with auxiliary power
HarryN is offline   Reply With Quote
Old 02-14-2019, 08:14 PM   #13
Platinum Member
 
rowiebowie's Avatar
 
Join Date: Jul 2018
Location: Texas
Posts: 1,102
Default

Thanks.

Thinking now of just putting a cheap battery monitor there that tracks voltage. I just couldn't justify the $$ Victron wants for their monitors, and their bluetooth system should give me much more information (without the need for a separate monitor). Still, I like having some battery information at-a-glance.
.
rowiebowie is offline   Reply With Quote
Old 02-14-2019, 08:58 PM   #14
New Member
 
Join Date: Feb 2019
Location: Pleasanton CA
Posts: 18
Default

Panel volt meters are fairly accurate.

Bogart makes some nice SOC setups.
__________________
Some experience with auxiliary power
HarryN is offline   Reply With Quote
Old 02-21-2019, 06:24 PM   #15
New Member
 
llemberg's Avatar
 
Join Date: Apr 2010
Posts: 4
Default

You can safely run 12V through an unused ethernet cable. The question is how much current will it carry? The answer is, it can handle what you want to do. You should remove the ethernet connectors at each end. Tie four of the wires together and use them for plus 12V, mark them with red tape. Make VERY sure you tie the SAME four wires together at both ends of the cable. If you don't, you will see lots of smoke when you hook it to the battery. Tie the other four wires together and use them as the Ground or return, mark them black or green. Four 26AWG wires tied together in parallel can handle the current of a single 20AWG conductor, which is 1.5Amp for Direct Current. At 1.5 Amp, the voltage loss across 15 feet of this cable is less than 1/2 volt, leaving 11.5V available for your USB, which is plenty. Your USB converter will convert the 11.5V to 5V for the USB device plugged into it. If that device tries to pull more than 1amp of current through your 1amp USB converter, the USB converter will either fail or protect itself from overload and shut down, but the wire will not be an issue.
Lars
__________________
Lars
2002 EVC, GoWesty restored in 2014
llemberg is offline   Reply With Quote
Old 02-21-2019, 06:28 PM   #16
Site Team
 
avanti's Avatar
 
Join Date: Jul 2013
Posts: 3,380
Default

Quote:
Originally Posted by llemberg View Post
Tie four of the wires together and use them for plus 12V, mark them with red tape. Make VERY sure you tie the SAME four wires together at both ends of the cable.
....or:
Tie all 8 wires together and use the chassis as ground.
__________________
Formerly: 2005 Airstream Interstate (Sprinter 2500 T1N)
Now!: 2014 Great West Vans Legend SE (Sprinter 3500 NCV3 I4)
avanti is offline   Reply With Quote
Old 03-12-2019, 12:53 AM   #17
Platinum Member
 
Join Date: Mar 2014
Location: Herndon, Virginia
Posts: 248
Default

That is about the best idea...8 #awg 26 wires work out to 1 #17 awg.
JohnnyFry is offline   Reply With Quote
Old 03-12-2019, 09:51 PM   #18
Gold Member
 
Join Date: Oct 2018
Location: QC
Posts: 96
Default

Could you not pull a new cable using the Cat5 cable as a fish?
__________________
2019 Roadtrek Simplicity SRT
Yoshimura is offline   Reply With Quote
Old 03-12-2019, 10:15 PM   #19
Platinum Member
 
rowiebowie's Avatar
 
Join Date: Jul 2018
Location: Texas
Posts: 1,102
Default

Quote:
Originally Posted by Yoshimura View Post
Could you not pull a new cable using the Cat5 cable as a fish?
No. there was no "give" on either end even after I unbundled the CAT wire from others nearby. It runs under the floor from street-side to curb-side, so I was not surprised the wires were not pulling freely.
.
rowiebowie is offline   Reply With Quote
Old 03-14-2019, 12:08 AM   #20
Bronze Member
 
Join Date: Mar 2019
Location: San ?Jose
Posts: 39
Default How about

Using the cat 5 as a feeder line to pull through a rope or string. Then use that line to pull the cat 5 and a thicker guage wire through.

If I were you, I would be pulling off panels and putting in the proper line to prevent fire hazard, but I know it's lots of work.....
__________________

chris_g19 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Featured Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT. The time now is 09:53 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
×