I'm hoping you guys will be able to troubleshoot this for me as I am totally baffled...Background:-In our former TV cabinet, we had a 12V outlet on the same plate as the coax jack. It didn't work. Took it out and found there were no 12V wires attached whatsoever. Bummer.-Beneath our former TV cabinet, we had the standard coax jack with the antenna amp button. No 12V outlet there. I saw the combo plate online and ordered it several years ago. But, when I removed the existing antenna amp plate the 12V wires only read ~8V on the multimeter. Huh? Abandoned that plan and just lived for a few years with no 12V outlet in coach.Current:-Getting geared up for solar install. Would like to install some 12V outlets (plus my control panel battery readout stopped working, so would like a 12V outlet to use with my cheapy 12V plug in meter until the TriMetric is installed). So, I revisited the 12V wiring situation, and found the following:--->The antenna amp plate still reads ~8.xxV (we've never used the antenna or a TV).--->The light above the sink (just a few cabinets down from antenna amp plate (maybe 5 feet max) reads 6.xxV????? The LED light I installed works.--->Decided to check voltage at charger/converter (WFCO WF8955AN) and found the ~8V circuit. Pulled the fuse and it was blown! Have no idea how/why a blown fuse was passing partial voltage. Replaced fuse and now have 12V to the antenna amp plate. Yay! Installed and now have one functional 12V outlet in coach!My Question:-Any ideas about the 6V at my light? I didn't unscrew any other lights to check them...I kind of threw in the towel for the night. All the other circuits on the charger/converter seem to be okay (i.e. match the battery output which was about 12.9V if I remember correctly).-I did the above testing on battery power only. Should I plug in and see if there is a difference? Any other ideas?

LED's will work with lower than printed voltage.. I have, not far from me, an indicator lamp assembly.. The body of the assembly says 12 volt.. The volt meter says 5, works fine.Some LED's are "Current limited" and more or less ignore supply voltage, some have built in voltage regulators and thus can take far less (or more) voltage than what you think they can.. I use a test LAMP (old fashion hot wire kind) to load test wiring.

Thanks for the input. I should probably clarify my question a bit... I'm trying to figure out why I only have 6V at that light? That doesn't seem right. What sort of troubleshooting should I be doing to track down the problem?

Is the fixture a regular RV fixture that takes classic 1156 bulbs and you have installed LED direct replacements with the 1156 style lamp base or is it a modern LED fixture and you removed the LED lamp and have tested the LED lamp socket?

It's the original fixture with eBay plug-n-play LED lights. And I unscrewed it from beneath the cabinet and am metering the incoming power wires.

What meter are you using? Checked the battery in the meter recently?

Weird 12V question for you electric gurus... | Good Sam Community

17 Replies

RJsfishin
Explorer
May 20, 2014
Are you metering between a known pos & neg wire, or a switched pos wire ?
johndeerefarmer
Explorer III
May 20, 2014
Sounds like your fuse wasn't completely blown open but had a very high resistance. You probably used a digital multimeter which has a very high impedance. Since it didn't put any load on the circuit your meter read some voltage. Next time either use an analog meter or as was suggested a 12V test light to "load" the circuit to get an accurate reading.
Are you saying that after replacing the fuse the voltage still reads 6 volts? If so then there is a high resistance between the fuse and the point that you are checking. Take a 12V incandescent bulb and put it across the wiring and at the same time check the voltage reading. If it's a high resistance the voltage should now be lower than before due to the increased load of the incandescent over the LED. Then check the wiring connections between the breaker and the lamp. You probably have a loose connection. A loose connection can have a higher resistance. This higher resistance drops more of the supply voltage therefore you are not getting the full 12V at the light.
westend
Explorer
May 20, 2014
What meter are you using? Checked the battery in the meter recently?
alliemac9
Explorer
May 20, 2014
It's the original fixture with eBay plug-n-play LED lights. And I unscrewed it from beneath the cabinet and am metering the incoming power wires.
youwillforget
Explorer
May 20, 2014
Is the fixture a regular RV fixture that takes classic 1156 bulbs and you have installed LED direct replacements with the 1156 style lamp base or is it a modern LED fixture and you removed the LED lamp and have tested the LED lamp socket?
alliemac9
Explorer
May 20, 2014
Thanks for the input. I should probably clarify my question a bit... I'm trying to figure out why I only have 6V at that light? That doesn't seem right. What sort of troubleshooting should I be doing to track down the problem?
wa8yxm
Explorer III
May 19, 2014
LED's will work with lower than printed voltage.. I have, not far from me, an indicator lamp assembly.. The body of the assembly says 12 volt.. The volt meter says 5, works fine.

Some LED's are "Current limited" and more or less ignore supply voltage, some have built in voltage regulators and thus can take far less (or more) voltage than what you think they can..

I use a test LAMP (old fashion hot wire kind) to load test wiring.

Forum Discussion

Weird 12V question for you electric gurus...

17 Replies

About Technical Issues

Related Content

Electric

Calling electrical gurus

Electrical assistance

Have a question for the electrical gurus.

Need Solar Guru Help!