General wiring misunderstanding on Nash22H
Hi, I have a 2001 Nash 22h that is new to us. I just modified battery brackets to accept 2 new Trojan 6V T105 batteries. At same time I installed a Pico master disconnect switch rated for 300A continu...
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Usually the disconnect switch is placed in the positive battery lead, I suspect because the negative is often chassis ground and it's too easy to get unwanted sneak paths around the disconnect, especially when there are some things that must be powered all the time. (For example, the emergency breakaway switch circuit for trailer electric brakes should be powered regardless of the battery disconnect state.)
The current sense doesn't sound backwards to me. The current that goes out the positive lead from the converter needs to go into the negative lead, and vice-versa for the battery. (Technically, of course, the current mostly consists of electrons flowing, and as they are negatively charged it physically flows out of the negative pole of the source and into the positive. Nevertheless, by convention the sign of measurements assumes positive charge carriers. Blame Benjamin Franklin, who had no way of knowing what polarity was correct and guessed wrong.)
Wiring the converter to the DC power panel is not at all unusual, but by no means universal. It does mean that with the battery disconnected, you can use the converter to power the RV systems. The alternative (which seems a little more useful to me, and actually happens to be how my RV is wired up) is to connect the converter to the battery side of the battery disconnect, which means you can recharge with the disconnect switch open but not have live RV house circuits.
I think the PD 9140 doesn't have red and white leads, but two screw terminals that the maker of the RV attaches wires to. If there are red and white wires, by convention the red almost always would be the positive and the white the negative.
To track down your voltage drop, measure the voltage difference between the converter and the battery in the positive wire and in the negative wire, and scrutinize the side of the circuit that has excessive voltage. Even with a relatively long wire run and possibly marginally sized wires, I would not expect a 0.7 volt drop at 21A. My hunch is that you have a poor ground connection at either the converter output or the battery ground connection...but I could very well be all wrong.
The current sense doesn't sound backwards to me. The current that goes out the positive lead from the converter needs to go into the negative lead, and vice-versa for the battery. (Technically, of course, the current mostly consists of electrons flowing, and as they are negatively charged it physically flows out of the negative pole of the source and into the positive. Nevertheless, by convention the sign of measurements assumes positive charge carriers. Blame Benjamin Franklin, who had no way of knowing what polarity was correct and guessed wrong.)
Wiring the converter to the DC power panel is not at all unusual, but by no means universal. It does mean that with the battery disconnected, you can use the converter to power the RV systems. The alternative (which seems a little more useful to me, and actually happens to be how my RV is wired up) is to connect the converter to the battery side of the battery disconnect, which means you can recharge with the disconnect switch open but not have live RV house circuits.
I think the PD 9140 doesn't have red and white leads, but two screw terminals that the maker of the RV attaches wires to. If there are red and white wires, by convention the red almost always would be the positive and the white the negative.
To track down your voltage drop, measure the voltage difference between the converter and the battery in the positive wire and in the negative wire, and scrutinize the side of the circuit that has excessive voltage. Even with a relatively long wire run and possibly marginally sized wires, I would not expect a 0.7 volt drop at 21A. My hunch is that you have a poor ground connection at either the converter output or the battery ground connection...but I could very well be all wrong.
