 |
|
05-11-2022, 06:14 AM
|
#1
|
Senior Member
Join Date: Sep 2020
Posts: 1,099
|
Weird electrical question, getting 8 volts?
I am placing phone chargers and USB chargers into my 2000 Winnebago ultimate advantage.
Easy to do, just wiring into the 12V system.
Put several on the dash (off cigarrette lighter wiring).
Several on the passenger wall (off the wall lights).
Tried to do the same on the drivers slideout. Wired to the wall lights, wouldn't work. Weird. Checked voltage, and it was 8 volts?!
Both chassis and house batteries 12.8v+. All other 12v lights, at 12v+...
But, lights on slide out at 8v. They work fine as they are LED, and you cant tell its a lower voltage by looking at them. But the USB charger needs 12+ volts.
How in the world is it 8 volts? No other lights on in the RV. Nothing else running. No light dimmer switch that I have ever seen. No wiring in series that I see that might lower the voltage.
How is that possible??? Is there some kind of voltage regulator? If so, why just for those 3 wall lights???
Only other electrical thing on the slideout is the microwave, that's off 120v, and works fine...
|
|
|
 |
Join the #1 RV Forum Today - It's Totally Free!
iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!
You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!
|
05-11-2022, 06:26 AM
|
#2
|
Senior Member
Join Date: Nov 2018
Location: Beaver Dam, Wisconsin
Posts: 3,294
|
As you suggested, it must be something in series. Maybe a corroded or loose connector. Maybe a crack in insulation followed by corrosion. Maybe loss of ground and now passing through another appliance.
__________________
Paul Bristol
Kodiak Cub 176RD
Nissan Pathfinder 2015
|
|
|
05-11-2022, 06:34 AM
|
#3
|
Member
Join Date: Dec 2021
Posts: 37
|
Weird electrical question, getting 8 volts?
It’s possible you have a bare wire slightly grounded somewhere and that’s where the other 4 volts are going. You could eliminating some of the lights on the circuit and see if for some reason one of them is introducing resistance into the circuit.
|
|
|
05-11-2022, 06:53 AM
|
#4
|
Senior Member
Winnebago Owners Club Workhorse Chassis Owner
Join Date: May 2016
Location: Kamloops, BC, 60 miles from the Center of the Universe
Posts: 6,073
|
Try running a separate ground wire. Bad grounds do strange things.
__________________
Happy Glamping, Norman & Elna. 2008 Winnebago Adventurer 38J, W24, dozens of small thirsty ponies. Retired after 40 years wrenching on trucks! 2010 Ford Ranger toad with bicycles or KLR 650 in the back. Easy to spot an RVer, they always walk around with a screwdriver or wrench in one hand!
|
|
|
05-11-2022, 07:01 AM
|
#5
|
Senior Member
Join Date: Sep 2020
Posts: 1,099
|
Hmmm. Good ideas so far. Like the idea of a new ground. It is on the slide out, so perhaps a grounding strap somewhere...
|
|
|
05-11-2022, 07:05 AM
|
#6
|
Member
Join Date: Dec 2021
Posts: 37
|
Quote:
Originally Posted by bpu699
Hmmm. Good ideas so far. Like the idea of a new ground. It is on the slide out, so perhaps a grounding strap somewhere...
|
Keep in mind, until you eliminate the grounded supply wire, adding a ground strap won’t fix the problem. You could cut the supply wire at a convenient location and attach a 12v battery to it and help narrow the problem area. If it is no longer grounded after you splice the battery into the circuit then you know you’ve cut the ground out of the circuit. if nothing else, run a new supply wire if it’s not too big a deal.
|
|
|
05-11-2022, 07:11 AM
|
#7
|
Senior Member
Join Date: May 2018
Posts: 1,233
|
My vote is for a bad ground (negative). When there is a poor or open ground connection it can cause downstream loads to back feed thru the upstream loads creating a series circuit as the current finds it's way back thru the loads. It shows up as dimming on lighting loads Run a temporary ground (negative) to the loads in question to prove.
|
|
|
05-11-2022, 07:34 AM
|
#8
|
Member
Join Date: Dec 2021
Posts: 37
|
Weird electrical question, getting 8 volts?
To check for a grounded circuit unhook both ends of your circuit from the termination points and use a multimeter to check from one end of the the circuit to ground. Meter should read OL or .1. This number needs to be non existing or very low. A high resistance means that circuit is touching ground somewhere.
|
|
|
05-11-2022, 08:16 AM
|
#9
|
Senior Member
Join Date: Sep 2018
Location: Fort Myers, FL
Posts: 1,295
|
Quote:
Originally Posted by cdc76
To check for a grounded circuit unhook both ends of your circuit from the termination points and use a multimeter to check from one end of the the circuit to ground. Meter should read OL or .1. This number needs to be non existing or very low. A high resistance means that circuit is touching ground somewhere.
|
I didn't understand this, sorry.
If you disconnect both ends of the pair of wires (positive and negative/ground) from the appliance AND from the source (battery or last connector in-line), they should be floating. If a reading from either wire to "real" ground is 0 or very low that would indicate that wire has a short to ground somewhere along it's disconnected length. A high resistance would mean it is not shorted to ground.
As I said, I didn't understand the instruction.
__________________
2008 Phaeton 36QSH, Safe-t-Plus, Quadra Bigfoot
2017 Jeep Cherokee Trailhawk w/ flat tow wiring mod.
Blue ox, BrakeMaster + BrakeAway, diode lights and charge.
|
|
|
05-11-2022, 08:26 AM
|
#10
|
Senior Member
Join Date: May 2018
Posts: 1,233
|
Quote:
Originally Posted by cdc76
To check for a grounded circuit unhook both ends of your circuit from the termination points and use a multimeter to check from one end of the the circuit to ground. Meter should read OL or .1. This number needs to be non existing or very low. A high resistance means that circuit is touching ground somewhere.
|
A LOW or zero resistance means a short or a heavy load, a high or infinite resistance means little to no conductivity. A moot point anyway for the ground (negative) wire since if it shorted to ground on a 12 volt 2 wire DC system it wouldn't affect the circuit operation. If the positive side shorted to ground it would normally take out the overcurrent protection device, a partial short is almost an impossibility unless it is passing thru a load with enough resistance to keep the current below the trip point of the OCPD, then it becomes a series circuit like I described in my earlier post.
Simplest and quickest way to check is a temporary wire from negative to the connection point where the low voltage problem exists, if that fixes it you know the ground (negative) path is poor and you can route a new wire from a known good location.
|
|
|
05-11-2022, 08:39 AM
|
#11
|
bnb1313@aol.com
Monaco Owners Club
Join Date: Feb 2008
Location: Western Montana on the Divide
Posts: 1,560
|
Try holding the switch down in the on position. My lights will dim or brighten by holding the switch down. Unsure if your system is similar.
__________________
Bob Retired Army Traveling alone now, had to put Charlie the Beagle down :(.
2008 Camelot 40 PDQ 4 slides ISL400 towing a 2020 1500 GMC Sierra Denali 4x4 Crewcab
Western MT in summer, AZ, NV in winter
|
|
|
05-11-2022, 08:48 AM
|
#12
|
Member
Join Date: Dec 2021
Posts: 37
|
Weird electrical question, getting 8 volts?
Quote:
Originally Posted by Domo
I didn't understand this, sorry.
If you disconnect both ends of the pair of wires (positive and negative/ground) from the appliance AND from the source (battery or last connector in-line), they should be floating. If a reading from either wire to "real" ground is 0 or very low that would indicate that wire has a short to ground somewhere along it's disconnected length. A high resistance would mean it is not shorted to ground.
As I said, I didn't understand the instruction.
|
No, leave the appliances hooked up. Unhook the positive and negative from the battery. Ensure neither end is touching anything. Make sure you have your meter set to read ohms. Stick one lead to either wire (positive or negative side) and the other lead to a known ground. (A good paint, rust free spot of trailer frame should do it) This should be OL (open line) or will possibly 0.1 -0.5 (if it’s higher than I would call it a grounded circuit.) any reading other than OL means the ground and the wire are sharing a path somewhere. when I take lunch I will sketch up a quick diagram of what I’m trying to explain and post it.
Or like someone else mentioned if you have spare wire you can just connect a new wire from your negative terminal to the appliance and see if it corrects it.
|
|
|
05-11-2022, 09:15 AM
|
#13
|
Senior Member
Newmar Owners Club Entegra Owners Club
Join Date: Dec 2015
Posts: 882
|
Just FYI USB voltage is 5V, not 12.
__________________
2021 Entegra Aspire 44W
Previous: 2006 Newmar Essex 4508
2013 Tiffin Allegro Open Road
|
|
|
05-11-2022, 09:37 AM
|
#14
|
Senior Member
Join Date: May 2018
Posts: 1,233
|
Quote:
Originally Posted by Archer2
Just FYI USB voltage is 5V, not 12.
|
I'm sure the OP is using pre-made USB assemblies that connect to 12 volts and produce 5.
|
|
|
 |
|
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
|
|
Thread Tools |
Search this Thread |
|
|
Display Modes |
Linear Mode
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
|
» Recent Discussions |
|
|
|
|
|
|
|
|
|
|
|
|
|