Renogy DC-DC 20 A charger may generate "stray" voltage

[Dave27]

I found a curious situation, I just want to let others know about it. I had been pulling the camper and the DC-DC charger had been on. After I stopped, disconnected the truck, and turned off the main switch that disconnects the batteries from everything, I went to check some wiring with my multi-meter and found there was some voltage in the system. I found the source was the Renogy DC-DC charger. The voltage decreased with time. I assume there must be a capacitor or something like that in the charger that slowly discharges over time. This was unexpected, so I'm just sharing this observation.
Dave

[Jlawles2]

I wonder if you are experiencing something like ghost voltages. See the write up here https://www.fluke.com/en-us/learn/bl...al-multimeters There are a lot of lines in close proximity in and we all know the RV industry uses the best wiring with insulation out there.

[Guest]

I found a curious situation, I just want to let others know about it. I had been pulling the camper and the DC-DC charger had been on. After I stopped, disconnected the truck, and turned off the main switch that disconnects the batteries from everything, I went to check some wiring with my multi-meter and found there was some voltage in the system. I found the source was the Renogy DC-DC charger. The voltage decreased with time. I assume there must be a capacitor or something like that in the charger that slowly discharges over time. This was unexpected, so I'm just sharing this observation.
Dave

Dave,

How is your D+ wired in? Also the Renogy has a relay built in that is activated from the D+ wire where this relay may be sticking.

Jim

[Dave27]

Dave,

How is your D+ wired in? Also the Renogy has a relay built in that is activated from the D+ wire where this relay may be sticking.

Jim

The D+ is tied into the tail lights at the junction box between the wires from the 7 pin plug and the camper wires. I turn it on by using the parking lights.

[Dave27]

I wonder if you are experiencing something like ghost voltages. See the write up here https://www.fluke.com/en-us/learn/bl...al-multimeters There are a lot of lines in close proximity in and we all know the RV industry uses the best wiring with insulation out there.

that is an interesting article. I don't think it is the situation here. There were no other energized circuits. The only live wire was from the batteries to the shut off switch, and it didn't have a circuit to complete.

[Country Campers]

Was the voltage on the input or the output side?

Brian

[Dave27]

Was the voltage on the input or the output side?

Brian

It was on both sides.

[Country Campers]

It was on both sides.

That is interesting, I will check mine to see if I have any voltage on the input side when the truck is not attached.

Brian

[Dave27]

That is interesting, I will check mine to see if I have any voltage on the input side when the truck is not attached.

Brian

Note I observed this immediately after using the charger. I doubt you will see anything if it hasn't been charging. I could also see the voltage was dropping with time.

[AlexPeterson]

Note I observed this immediately after using the charger. I doubt you will see anything if it hasn't been charging. I could also see the voltage was dropping with time.

Dave - voltage drop over time - please give us a sense for how long this is. Minutes? Seconds? Thanks.

[Yoda]

Note I observed this immediately after using the charger. I doubt you will see anything if it hasn't been charging. I could also see the voltage was dropping with time.

Dave have you called Renogy. They may have an answer or can help. They were good helping me out with my install questions a while back. It sounds like a capacitor discharging over time) - probably normal. I wonder if Will Prowes ever tore his down - he liked them in his review

Just drinking coffee before shoveling more snowand it's cold out there - not even 20F yet.

Keith

[Dave27]

Dave - voltage drop over time - please give us a sense for how long this is. Minutes? Seconds? Thanks.

Minutes. I could see drops of tenths of volts after a few minutes. One of the things that confused when I first noticed this voltage is it was less than the battery voltage.

[Guest]

Dave27 Dave where is the output side of the Renogy connected? Also has your battery switch been re-wired to provide a complete disconnect? I'm wondering if (depending how this is wired) if other components in the rig are back feeding until memory functions are depleted. Items such as CO, radio, and so on.

Jim

[Dave27]

Dave27 Dave where is the output side of the Renogy connected? Also has your battery switch been re-wired to provide a complete disconnect? I'm wondering if (depending how this is wired) if other components in the rig are back feeding until memory functions are depleted. Items such as CO, radio, and so on.

Jim

It goes to the positive buss bar, along with the DC output from the converter, solar controller, inverter, the batteries (after the shut off switch), and the wire to the camper. When I disconnected the DC-DC charger there was no more voltage in the system.
Dave

[Guest]

It goes to the positive buss bar, along with the DC output from the converter, solar controller, inverter, the batteries (after the shut off switch), and the wire to the camper. When I disconnected the DC-DC charger there was no more voltage in the system.
Dave

With the unit disconnected, it must incorporate a CAP. Maybe used to condition voltage.

Jim