Updated: Bedroomlight voltage drop

[Steven P]

My 06 Diplomat has 2 ceiling lights in the bedroom.  I changed the bulbs from fluorescent to M4 Led tube bulbs several months back.  I kept having flickering issues and today pulled the fixture down and found a loose 12V connection where the PO spliced in the second light.  I fixed and checked all the connections and the lights are working well again.  But here's my question: I see 12.3V at the switch on the wall.  I have 1 switch for both lights. The lights each have 9.4V at their source wire while they are on.  The Magnum is reading 13.0 float charging and I'm plugged in to 110v. Plenty bright.  Is this normal for this type of situation?  Seems like a significant voltage drop.  Also, I have 2 12V house batteries and am questioning how good they are.   I'm waiting on Sam's to have a sale.  @Hotrod

Thank you, 

Steven 

Edited December 19, 2020 by Steven P

[Harvey Babb]

That is more drop than I would expect, especially since you switched to LED.

Get a long jumper wire and ground your meter back to the chassis and start going down the line to see where the drop is occurring. 

In general, anything over a 10% drop (except in starting circuits)  is excessive.

While you're checking, also check the voltage on the ground wire of the circuit because a high resistance in the ground will reduce voltage at the load as well.

[dl_racing427]

7 hours ago, Harvey Babb said:

That is more drop than I would expect, especially since you switched to LED.

Get a long jumper wire and ground your meter back to the chassis and start going down the line to see where the drop is occurring. 

In general, anything over a 10% drop (except in starting circuits)  is excessive.

While you're checking, also check the voltage on the ground wire of the circuit because a high resistance in the ground will reduce voltage at the load as well.

This is true, especially if the ground wire goes all way back to the switch, you're doubling the current path to the lights.

That is a lot of drop in the wiring.  Measure the current draw by putting your meter in amp mode and placing it across the switch terminals with the switch off.
Then check the wire gauge and length to see if it's too small a wire.

[Bob Nodine]

Agree with everyone about the drop being excessive. For that kind of drop you would expect the current to be higher than what two LED fixtures would draw. Are you sure that the 12 VDC ballasts have been removed from both fixtures? Remove the cover between the tubes and completely remove the ballast circuit and wiring.

[Steven P]

10 hours ago, Bob Nodine said:

Agree with everyone about the drop being excessive. For that kind of drop you would expect the current to be higher than what two LED fixtures would draw. Are you sure that the 12 VDC ballasts have been removed from both fixtures? Remove the cover between the tubes and completely remove the ballast circuit and wiring.

Yes, I followed the instructions from M4LED as written and removed the ballasts and wired them per their instructions.  He's been responsive to my emails too and is helping troubleshoot.  All agree the voltage drop is excessive.  I've got some more troubleshooting to do.  Thank you all. 😊

[Bob Nodine]

10 hours ago, Steven P said:

Yes, I followed the instructions from M4LED as written and removed the ballasts and wired them per their instructions.  He's been responsive to my emails too and is helping troubleshoot.  All agree the voltage drop is excessive.  I've got some more troubleshooting to do.  Thank you all. 😊

Steven,

You might investigate if the previous owner connected something else to the same circuit.

 

[Steven P]

As mentioned in the first post, he installed a second ceiling light and spliced into the wires for the first one.  But I still don't think it should drop that much.  @Bob Nodine

[Bob Nodine]

2 hours ago, Steven P said:

As mentioned in the first post, he installed a second ceiling light and spliced into the wires for the first one.  But I still don't think it should drop that much.  @Bob Nodine

Steven,

I did not explain myself very well, I meant in addition to the second ceiling light fixture. Maybe there is something else connected besides the two light fixtures. I am just trying to understand the larger than expected current draw.

 

[Steven P]

21 hours ago, Bob Nodine said:

Steven,

I did not explain myself very well, I meant in addition to the second ceiling light fixture. Maybe there is something else connected besides the two light fixtures. I am just trying to understand the larger than expected current draw.

 

Gotcha, from all I can tell, there is nothing else connected.  I have not found anything else that switch controls or seems affected by it.  I'll pull down the other light soon and see what lies underneath.  Thank you. 

[W7BE_Bob]

As stated above measure both the positive and negative voltages from frame ground which will reveal a ground connection issue. With the switch on post the voltages to the switch, lights and the lights negative wire. Do this with the Magnum on as your batteries are questionable. Also if possible measure and post the amps.

If possible check the accuracy of your voltmeter and if not then post the Magnum voltage vs a reading on the house battery terminals where the difference should be minor with low amp charging.

Also, as a priority item have the house batteries load tested, auto stores will do this for free and a good battery shop can do this with the batteries installed. Are these starting batteries? Surely a 06 Diplomat did not come with 2 12V starting batteries?

[Steven P]

Doing some troubleshooting now and made some discoveries that the PO added, but not sure they matter.  These wires all meet in a cabinet and there are 2 factory lights installed there.  The PO added a 12v fan and a separate light fixture that uses solid copper wire for its wiring.  I unhooked the fan AND the added light and took measurements with them unhooked.  For ground, I do not have a long enough wire on me for frame ground,  but have compared using the round hole in the AC outlets and the ground wire from the CO detector and get consistent readings. 

2 hours ago, W7BE_Bob said:

 Are these starting batteries? Surely a 06 Diplomat did not come with 2 12V starting batteries?

The PO installed 2 12V marine batteries for the house batteries.  I'm hoping to see Sam's have a GC2 sale soon. 

At switch:  12.89v with lights off, 12.58v with one light on and 12.26v with both lights on.  

Amps at switch: 0A off, 0.043A w one light on and 0.067A with both on. 

At the light located further back: 11.06V if both on, 12.0V if this one on and front off,  12.08V if this one off and front on, 12.84V w both off.  Amps: 0.04A with one on and 0.031A if both on. 

Checked battery voltage at battery posts and see 13.05V, Magnum going from 13.0 to 13.1V. 

Rechecked at switch and voltage dropped a little: 12.84V off, 12.55V w one light on, and 12.19V w both on. 

Rechecked my water levels in my 2 batteries, one was fine, had to add water in 4 of the 6 cells in the other.  Levels were just below the line.  Water was Last checked fine about a month ago.  

I believe I'll take em for testing next. 

I may have found one issue:  with the added hall light (solid wires) and fan unhooked: I rechecked the voltage.  I am seeing 12.58V at the pos and grounded to either the CO ground or the wall outlet, but 12.3V when hooked straight to the associated ground wire. Same thing if I hook pos on the meter to the pos on the CO detector and use the ground associated w the lights. Problem is that wire disappears into the wall. 

Edited December 16, 2020 by Steven P

[Steven P]

Update:  both 12V batteries failed.  One had 12.7V but failed load test.  Other had 8.8V after being on charger and failed load too.   Both read 13.1V at coach on charger.  

I am gonna wait til after Christmas hoping for a sale on the Duracells (currently$180 each). But anyone have experience w Diehard 6V GC2 AGMs?  They are $130 each at Advanced Auto.  O'Reilly has some but they are $200 each.  I'm going w AGMs to save maintenance for me.  I have enough going on without adding battery maintenance.  😃

 

Thanks again for all the help. 

[W7BE_Bob]

0.07A is very small as expected with LEDs. Apparently there is a wiring issue, probably a bad connection. As an example: IF you had 400' of 16ga wire at 13.0V and 0.07A the drop would be 0.11V or 12.9V at the lights. Could be a bad switch. With the switch on what is the voltage across the switch terminals? Should be 0.0V.

Attach a long wire (14-16ga) to a good connection directly on the frame as you want to eliminate any other wiring. Connect the wire to your voltmeter and measure both the + wire at the light which should be 12.9V and if so it's OK. The - wire should be 0.1V and if so it's OK. This will isolate which wire (hopefully not both) is the problem. You can also connect that wire to the negative light wire to see if it's the negative light wire that  is  e switch off connect it to the light + side and switch light side to help isolate the wiring problem. 

 

- 

 

Good job as strange and unexpected  symptoms can show up with bad batteries. Recheck the light voltages with the new batteries.

[Steven P]

Magnum inverter/setup questions for when I get new batteries.  Waiting til after holidays for batteries (hoping for a sale).   When I do install them, they will be 4 6V AGM batteries in series parallel.  So my question goes w setting up the Magnum charger. I know to change the battery type to AGM,  but what other settings are recommended for best performance and to help keep them lasting a long time?   Charge rate? Cut out volts?   Should they never go below 12.0V?  I see that mentioned a lot, but thought they could drop to 11.5V without harm?  Thanks again,

Steven 

[96 EVO]

Apparently AGM's can take a little higher charge rate than FLA, so assuming your Magnum has a 100A charger, you could bump the charge rate up to 70 or 80%.

[Harvey Babb]

I'd like to point out one SERIOUS problem with the measurements you have taken.

The meter used is for AC only, and will not give accurate readings of DC current.

 

[Steven P]

5 hours ago, Harvey Babb said:

I'd like to point out one SERIOUS problem with the measurements you have taken.

The meter used is for AC only, and will not give accurate readings of DC current.

 

I wondered about that.  I am not new to using voltmeter, but am new to using reading amps.  I don't think my meter can read DC amps.  Do have a recommendation for a good DC ampmeter?

 

[W7BE_Bob]

9 hours ago, Harvey Babb said:

I'd like to point out one SERIOUS problem with the measurements you have taken.

The meter used is for AC only, and will not give accurate readings of DC current.

 

Excellent catch and this type of meter is rather common. Clampons that read AC and DC amps are available at HD Lowes etc. If if says DC read on as it must also say DC AMPs. These under $100 meters are adequate for RV usage while better ones like Fluke are $300+. ie More accurate, faster reading and other features not generally needed for RV work.  

Amazon has a variety of meters under $50.

[Onthego]

I agree with Bob on the chose of meter. I bought an inexpensive meter from Amazon that was a surprise, it measure DC  current very accurately next to my Fluke. Maybe I will add a link to the meter check it out $39.

https://www.amazon.com/dp/B01N014USE?psc=1&ref=ppx_pop_dt_b_product_details

 

[Harvey Babb]

@Onthego Thanks for the suggestion and the link! I've been thinking about a DC clamp on for a while and I like the looks of this one!

 

[Harvey Babb]

17 hours ago, Steven P said:

I wondered about that.  I am not new to using voltmeter, but am new to using reading amps.  I don't think my meter can read DC amps.  Do have a recommendation for a good DC ampmeter?

 

See post from Onthego above. I looked at it and immediately ordered one from Amazon; I think it'll do nicely! 🙂

 

[dl_racing427]

21 hours ago, Onthego said:

I agree with Bob on the chose of meter. I bought an inexpensive meter from Amazon that was a surprise, it measure DC  current very accurately next to my Fluke. Maybe I will add a link to the meter check it out $39.

https://www.amazon.com/dp/B01N014USE?psc=1&ref=ppx_pop_dt_b_product_details

 

Lots of useful features on this.  Looks like a great deal if it's accuracy is good.
The only thing lacking is true RMS AC measurements.  This is usually only on considerably more expensive meters.