Some electrical upgrades
I've recently finished up (at least for now) some electrical upgrades and enhancements to my motorhome. Here's the brief list; read on for more details if you're interested.
Before:
A pretty standard sort of monitor panel and generator panel. (This is Coachmen's particular variant.)
After:
Pay no heed to the dark smudge on the upper right part of the panel. That's just dust on my camera sensor.
The upper left meter is this voltmeter/thermometer/clock combo, and the pushbuttons next to it are its mode and time set buttons. On my particular meter, the clock is quite inaccurate, losing several minutes per day, but the voltmeter agrees very well with my (not recently calibrated but believed accurate) Fluke, and the thermometer seems plenty accurate for my needs. The temperature probe is out underneath the RV and so this measures outside temperature. The voltage sense is taken more or less directly from the battery.
The lower left meter is this ammeter powered by a tiny isolated DC/DC converter; this allows measurement of current bidirectionally. In my case this is battery current—positive for charging, negative for discharging, as that sign convention seemed to me to make the most sense. It does not show current from the converter to the house loads when plugged into shore power. Naturally, what is measured depends on the placement of the shunt in the circuit.
The rocker switch on the far left turns off these two meters, mainly for fear of excessive nighttime light pollution. The power consumption of these sorts of little panel meters is negligible (probably less than a tenth of an amp total for this setup).
The doohicky in the middle of the panel is the PD9245 remote pendant.
The meter on the right side is this nifty AC line monitor which shows AC voltage, current, power, and energy consumption (i.e. volts, amps, watts, and watt-hours or kilowatt-hours). It is purely a single phase device, so it would not be ideal for a 50A RV—you would need one for each leg, and do addition if you cared about the total energy consumption—but since I have a 30A supply it works just fine. The current sense transformer is around the main input feed to the electric panel, after the ATS, and the voltage sense lines are tapped into one of the branch circuits near the electric panel (with a low-value fuse to protect the line to the meter). I used a four-conductor 18 gauge fire alarm wire to connect the meter to the voltage and current taps; this is UL listed for use up to 300V.
The AC meter does appear to properly handle devices with poor power factors; the power displayed is not always the product of the voltage and current.
I have not checked the calibration of either the DC or AC ammeters, but they both pass TLAR inspection with flying colors.
The panel itself is a thin piece of plywood attached to the existing cabinetry (also a thin piece of plywood) with some small standoffs. The existing level meters and generator controls remain mounted on the old panel, along with the converter remote pendant, with cutouts in the new panel for them. Among other things, this lets me hide the wire to the pendant. It also was a lot easier to mount and wire the switches and whatnot for the DC meters without having to do it in the little enclosed space above the refrigerator.
Coachmen's original configuration of the circuitry around the house battery is something like this, as far as I could make it out:
While there's nothing really wrong with this, there were a few things I didn't particularly like. Chief among them was the connection of the converter and the house loads to the same 40A circuit breaker. This meant that any upgraded converter would not be able to charge the battery any faster than a 40A rate; it also meant that the power available for house loads would vary greatly based on whether the converter was active or not. (If on, the house loads could total up to 40A plus the converter current, or 80A with the factory converter; if off, they could only total up to 40A before the circuit breaker would put a halt to things.) This was not a safety hazard as shipped from the factory as the wiring to the house loads was sufficiently large to handle an 80A current, but it struck me as a sloppy design and one that would have trouble working with any upgraded converter with a higher current capacity.
I also was interested in adding some additional connections near the battery, and it was all starting to look like it might get kind of generally messy, so I made some revisions and added a secondary 6 slot fuse panel:
Now the converter charge and house currents are both limited to 50A, which is well within the safety margin for these wires. The other "little" loads are connected to the new auxiliary fuse panel.
Here's an attempt at a photo with annotations of this part of the wiring. I put this in mainly in case someone else is puzzling over the similar wiring of their Coachmen RV; there's a good chance it bears some resemblance to this (well, to this as it used to be...so the connections to the circuit breakers would be a bit different).
Eagle-eyed readers may wonder if the wire to the new fuse panel is undersized. It's 10 gauge wire, which in open air (as here) is acceptable per the NEC for up to 40A. I would prefer to have a heavier wire here, but this is what I had available on hand and is safe. The voltage drop shouldn't be too much even in the worst case because it's a short wire, and in general it's not a concern because the typical current is much less than 40A in my case. Still, this is not ideal.
I don't have pictures of the EMS installation, but it's not really too interesting to look at. Imagine a black box deep in the recess behind some cabinets and underneath the range and you'll get a reasonable idea of what it might look like.
I put the EMS remote display in a cabinet wall a bit under the kitchen counter:
All in all, I was fairly impressed with the factory wiring that Coachmen did, especially when compared with some of the horrors I've seen here from other RVs. Everything seemed to be done safely and neatly and competently, and all the exposed wires underneath were run in protective split loom tubing, and things are generally accessible enough to work on.
The preparation for golf cart battery installation mainly consisted of trimming some material off of an oddly-placed angle iron above the house battery tray (not visible in the picture above due to the angle it's taken at) which projected down a part of an inch too far to permit a golf cart battery to be installed. This angle iron doesn't serve any useful structural purpose (it isn't supporting the floor or steps above, and provides no essential compressive or tension strength as it's installed just a couple inches from the main vehicle frame rail); as best as I can guess, it may be there to provide some protection for the LP gas line running behind it. At any rate, it's a rather slow and laborious process to cut angle iron lengthwise with a jigsaw (and that with a false bottom on the shoe so it can't reach said LP gas line).
- Added AC and DC metering
- Upgraded converter to PD9245
- Installed PI EMS
- Reworked the battery connection topography a bit
- Prepared for future battery upgrade to 2xGC2
Before:
A pretty standard sort of monitor panel and generator panel. (This is Coachmen's particular variant.)
After:
Pay no heed to the dark smudge on the upper right part of the panel. That's just dust on my camera sensor.
The upper left meter is this voltmeter/thermometer/clock combo, and the pushbuttons next to it are its mode and time set buttons. On my particular meter, the clock is quite inaccurate, losing several minutes per day, but the voltmeter agrees very well with my (not recently calibrated but believed accurate) Fluke, and the thermometer seems plenty accurate for my needs. The temperature probe is out underneath the RV and so this measures outside temperature. The voltage sense is taken more or less directly from the battery.
The lower left meter is this ammeter powered by a tiny isolated DC/DC converter; this allows measurement of current bidirectionally. In my case this is battery current—positive for charging, negative for discharging, as that sign convention seemed to me to make the most sense. It does not show current from the converter to the house loads when plugged into shore power. Naturally, what is measured depends on the placement of the shunt in the circuit.
The rocker switch on the far left turns off these two meters, mainly for fear of excessive nighttime light pollution. The power consumption of these sorts of little panel meters is negligible (probably less than a tenth of an amp total for this setup).
The doohicky in the middle of the panel is the PD9245 remote pendant.
The meter on the right side is this nifty AC line monitor which shows AC voltage, current, power, and energy consumption (i.e. volts, amps, watts, and watt-hours or kilowatt-hours). It is purely a single phase device, so it would not be ideal for a 50A RV—you would need one for each leg, and do addition if you cared about the total energy consumption—but since I have a 30A supply it works just fine. The current sense transformer is around the main input feed to the electric panel, after the ATS, and the voltage sense lines are tapped into one of the branch circuits near the electric panel (with a low-value fuse to protect the line to the meter). I used a four-conductor 18 gauge fire alarm wire to connect the meter to the voltage and current taps; this is UL listed for use up to 300V.
The AC meter does appear to properly handle devices with poor power factors; the power displayed is not always the product of the voltage and current.
I have not checked the calibration of either the DC or AC ammeters, but they both pass TLAR inspection with flying colors.
The panel itself is a thin piece of plywood attached to the existing cabinetry (also a thin piece of plywood) with some small standoffs. The existing level meters and generator controls remain mounted on the old panel, along with the converter remote pendant, with cutouts in the new panel for them. Among other things, this lets me hide the wire to the pendant. It also was a lot easier to mount and wire the switches and whatnot for the DC meters without having to do it in the little enclosed space above the refrigerator.
Coachmen's original configuration of the circuitry around the house battery is something like this, as far as I could make it out:
While there's nothing really wrong with this, there were a few things I didn't particularly like. Chief among them was the connection of the converter and the house loads to the same 40A circuit breaker. This meant that any upgraded converter would not be able to charge the battery any faster than a 40A rate; it also meant that the power available for house loads would vary greatly based on whether the converter was active or not. (If on, the house loads could total up to 40A plus the converter current, or 80A with the factory converter; if off, they could only total up to 40A before the circuit breaker would put a halt to things.) This was not a safety hazard as shipped from the factory as the wiring to the house loads was sufficiently large to handle an 80A current, but it struck me as a sloppy design and one that would have trouble working with any upgraded converter with a higher current capacity.
I also was interested in adding some additional connections near the battery, and it was all starting to look like it might get kind of generally messy, so I made some revisions and added a secondary 6 slot fuse panel:
Now the converter charge and house currents are both limited to 50A, which is well within the safety margin for these wires. The other "little" loads are connected to the new auxiliary fuse panel.
Here's an attempt at a photo with annotations of this part of the wiring. I put this in mainly in case someone else is puzzling over the similar wiring of their Coachmen RV; there's a good chance it bears some resemblance to this (well, to this as it used to be...so the connections to the circuit breakers would be a bit different).
Eagle-eyed readers may wonder if the wire to the new fuse panel is undersized. It's 10 gauge wire, which in open air (as here) is acceptable per the NEC for up to 40A. I would prefer to have a heavier wire here, but this is what I had available on hand and is safe. The voltage drop shouldn't be too much even in the worst case because it's a short wire, and in general it's not a concern because the typical current is much less than 40A in my case. Still, this is not ideal.
I don't have pictures of the EMS installation, but it's not really too interesting to look at. Imagine a black box deep in the recess behind some cabinets and underneath the range and you'll get a reasonable idea of what it might look like.
I put the EMS remote display in a cabinet wall a bit under the kitchen counter:
All in all, I was fairly impressed with the factory wiring that Coachmen did, especially when compared with some of the horrors I've seen here from other RVs. Everything seemed to be done safely and neatly and competently, and all the exposed wires underneath were run in protective split loom tubing, and things are generally accessible enough to work on.
The preparation for golf cart battery installation mainly consisted of trimming some material off of an oddly-placed angle iron above the house battery tray (not visible in the picture above due to the angle it's taken at) which projected down a part of an inch too far to permit a golf cart battery to be installed. This angle iron doesn't serve any useful structural purpose (it isn't supporting the floor or steps above, and provides no essential compressive or tension strength as it's installed just a couple inches from the main vehicle frame rail); as best as I can guess, it may be there to provide some protection for the LP gas line running behind it. At any rate, it's a rather slow and laborious process to cut angle iron lengthwise with a jigsaw (and that with a false bottom on the shoe so it can't reach said LP gas line).
