Random Taped Off Wire - Printable Version
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Random Taped Off Wire - Frankie4Fingers - 09-19-2024
Hey, does anyone know what this taped off wire is for? It is in the rear, passenger bay, back where the coach batteries are, just next to the engine. I have a 1998 DD series coach. It looks like it should be attached to the thing in front of it, but it is detached and it is electrical taped off.
Thanks in advance.
RE: Random Taped Off Wire - folivier - 09-20-2024
That thing looks like a shunt which is used to track how many amps you're using. Negative wires from your batteries are connected to it then continue on to your coach 12 volt systems.
Not sure why that heavy wire is not connected. Are there 2 separate shunts and one doesn't have any wires connected to it?
RE: Random Taped Off Wire - Richard - 09-20-2024
Forest is correct.
More details to follow. That is indeed a shunt. The side closest to you in the picture should have two small wires attached to the screw terminals on front. In the pic, you can see one attached, and on the other the small wire has been pulled out of its terminal. Originally those shunt wires would have feed the ammeter that was read using a XANTREX control panel for the inverter. If you selected BANK 2, it would show you the amps the alternator was putting into the batteries.
It is clear that the DC system has been altered just a bit. It is impossible to tell you if there is a problem, or how it should be configured without a detailed analysis and wiring diagram of the existing setup.
Some questions and simple analysis can be done to know what is and isn’t going on.
Start by opening the stainless door for the electrical cabinet in engine compartment and posting a pic of that.
With the coach unplugged and engine off, measure the voltage of both the chassis batteries and house batteries with a digital voltmeter. Record this number, because we will be looking for small changes in voltage.
Crank the engine, and use the High Idle switch on the drivers console to raise the engine RPM to a 1000 or so. Now measure the voltage on both battery banks again.
If the voltage is slightly higher on the chassis batts, the alternator is indeed charging the chassis batteries
If the voltage is slightly higher on the house batts, the alternator is charging the house batts as you drive.
Turn the high idle off, and shut the engine down.
Now plug the coach into 30 or 50 amp service.
Measure the voltages again.
If the voltage is slightly higher on the house batts, then the inverter is charging the house batteries while plugged in.
If the voltage is slightly higher on the chassis batts, then the inverter is also providing through and echo charger, a maintenance voltage to keep the chassis batts up while plugged in.
This sounds like simpleton stuff, but on a new to you coach, it is good to establish what is and isn’t going on with the DC system before delving into wiring changes.
RE: Random Taped Off Wire - Frankie4Fingers - 09-20-2024
(09-20-2024, 08:02 AM)Richard Wrote: Forest is correct.
More details to follow. That is indeed a shunt. The side closest to you in the picture should have two small wires attached to the screw terminals on front. In the pic, you can see one attached, and on the other the small wire has been pulled out of its terminal. Originally those shunt wires would have feed the ammeter that was read using a XANTREX control panel for the inverter. If you selected BANK 2, it would show you the amps the alternator was putting into the batteries.
It is clear that the DC system has been altered just a bit. It is impossible to tell you if there is a problem, or how it should be configured without a detailed analysis and wiring diagram of the existing setup.
Some questions and simple analysis can be done to know what is and isn’t going on.
Start by opening the stainless door for the electrical cabinet in engine compartment and posting a pic of that.
With the coach unplugged and engine off, measure the voltage of both the chassis batteries and house batteries with a digital voltmeter. Record this number, because we will be looking for small changes in voltage.
Crank the engine, and use the High Idle switch on the drivers console to raise the engine RPM to a 1000 or so. Now measure the voltage on both battery banks again.
If the voltage is slightly higher on the chassis batts, the alternator is indeed charging the chassis batteries
If the voltage is slightly higher on the house batts, the alternator is charging the house batts as you drive.
Turn the high idle off, and shut the engine down.
Now plug the coach into 30 or 50 amp service.
Measure the voltages again.
If the voltage is slightly higher on the house batts, then the inverter is charging the house batteries while plugged in.
If the voltage is slightly higher on the chassis batts, then the inverter is also providing through and echo charger, a maintenance voltage to keep the chassis batts up while plugged in.
This sounds like simpleton stuff, but on a new to you coach, it is good to establish what is and isn’t going on with the DC system before delving into wiring changes.
Wow nice lengthy answer. I do think the inverter was swapped out for a different one, so maybe they didn't need that wire to be connected?
RE: Random Taped Off Wire - Richard - 09-20-2024
Yes, that is sort of correct.
A new inverter may not have had the ability to pair with a second shunt. The first is in your house battery bay, btw. So the small wires were no longer needed.
However, I do not understand why the large ground cable is not connected. To provide more insight, you may have to physically trace the taped wire to its other end.
RE: Random Taped Off Wire - Frankie4Fingers - 09-20-2024
(09-20-2024, 06:35 PM)Richard Wrote: Yes, that is sort of correct.
A new inverter may not have had the ability to pair with a second shunt. The first is in your house battery bay, btw. So the small wires were no longer needed.
However, I do not understand why the large ground cable is not connected. To provide more insight, you may have to physically trace the taped wire to its other end.
Yea, it goes under the panel there really quickly. I will try to see if I can get some visibility under there or if I pull on it a bit it might wiggle in the battery compartment.
RE: Random Taped Off Wire - Richard - 09-21-2024
Corey,
The reason I went to the effort of the detailed instructions was the main DC power cables have been altered on your coach. It may be perfectly fine. May is the key word. In God we trust, all others bring data.
On a new to you coach, it would be a good investment of time to confirm that it’s current (no puns) wiring functions as the coach is supposed too.
An improper function with those cables has the potential for frying an alternator, or cooking either chassis or house batteries. All expensive items to replace.
RE: Random Taped Off Wire - Jack Houpe - 09-22-2024
Are you certain those are ground cables and not + 12vdc. For some reason I think I remember them being hot to ground when I was tracing out the echo charger line.