Power Transfer Switch Adventure
Well on this last holiday weekend I had an unexpected detour which seems par for the course with my bus.
As part of my home automation system; I wanted sensors for shore power/RV camping lots where it could detect the difference between a 120V and 240V external feed. I.E. on 120V it would need a user input over-ride to know that the external feed was 30 amps verse's a simple extension cord in someone's driveway; to know the maximum power that it could draw for air conditioners or hydronic tank heating.
So anyway I removed the cover from the power transfer switch to add wires for a 120V shore/eternal power presence sensor and discovered the following:
https://www.crystalpoint.com/cpdownl...itchBypass.jpg
Some previous owner had totally bypassed the entire transfer switch functionality; which seems to a major theme on my bus. I.E. If you don't understand it, just bypass it!!!
My buses transfer switch is an Todd Engineering PS2-245S which has the following power input modes:
1. Inverter power input
2. Shore/external power input
3. Generator input
I can see from the physical damage evidence what more and likely lead them down this path:
https://www.crystalpoint.com/cpdownl...tchBurnout.jpg
It looks like the switch had been used extensively in shore power mode and had a loose connection for the neutral wire, which heated it up to the point that it melted away the connection from the plastic mount on the external power input bus bar. Look at the orange box in the picture, for where the neutral connection should be.
It seems that whoever tried to fix it, couldn't read the electrical diagram that was inside of the cover.
https://www.crystalpoint.com/cpdownl...tchDiagram.jpg
Future note, be sure to use the cell phone to take pictures before you muck with things!!!!
Anyway what was expected to be a 20 minute task; turned out be a full day of figuring things out, but hey I fixed it and didn't have to spend $600.00+ to replace the power transfer switch.
It turns out in attempting to fix the melted neutral connection problem; they had rewired the generator input connection and shorted out the HOT2 to the neutral connection.
Which might explain why I also found both air conditioners in the bus wired to the HOT1 connection which had previously puzzled me as to why someone would do that!!!
They had probably ran for sometime with a blown generator fuse on HOT2 input lead, before taking a second pass at the problem.
Anyway functionally in this transfer switch is as follows:
1. The default connection is for inverter power input. Which initially confused me in decoding the circuit diagram; as I had thought that the power cord/shore power input would be the default.
2. When in power cord/shore power input mode; two relays are energized with one light showing on the top time delay board, after a 30 second delay.
3. When in generator input; all the relays are energized with both timer delay boards showing lights. The first timer delay light comes on after a 30 second delay and then the second after an additional three minute delay; before generator power is passed through to the house systems.
So anyway on to the next problem....
One-Wire Temperature Sensors
I absolutely love One-Wire sensors and have made liberal use of them in my bus.
A One-Wire device communicates via a single signal pin and can work up to 200ft with twisted pair wiring. So just three wires to handle signal, power and ground that works as a distributed electrical sensor bus.
Here's how they are hooked up to my Raspberry Pi controller for the bus:
https://www.crystalpoint.com/cpdownl...ds/OneWire.jpg
Another value point is that they are less than $3.00 a sensor for general use and around $20.00 for the inline liquid temperature sensing.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Note for the liquid sensor you want the 30mm version to use on a 1/2 pipe tee.
Each sensor has a unique ID that must be determined by adding one sensor at time and determining which id is the new one.
Here's the twelve sensors that I currently have installed in my bus.
//
// One Wire Id's DS18b20 Temperature Sensor
//
4D18940B0000 Hydronic output
1B6EE10B0000 Diesel boiler output
AA8B11481401 Generator Bay
AA35AF481401 Fresh Water Tank
AAF6A0481401 Forward Bay
AAC09E481401 Mid Bay
AA01BF471401 Battery Bay
AAE595481401 Plumbing Bay
F854950B0000 Engine Coolant (heater hose input to Glycol Heater/Tank 2)
AA9EA9481401 Under bus outside air temperature
AAF58F471401 Refrigerator
AAA09A481401 Freezer
This makes it very easy to monitor/alarm or automate desired functionality.
Inverter Node-Red Automation Bling
I just added my first bit of automation bling to manage the AC power inverter on my bus.
https://www.crystalpoint.com/cpdownl...verterFlow.jpg
I have a high power inverter 6KW (up to 18KW surge) that has a standby consumption of about 100 watts. So if it is left on 24/7 it will use 2.4KW of power. Given that my house battery bank currently stores about 9KW, that can be a major chunk of the out of the storage capacity.
Obviously not as much of a problem when the sun is shining and is generating solar power.
So anyway this node-red flow monitors the inverter while it is on and automatically shuts it down; when it has been idle for ten minutes. If there is a large draw it automatically extends the time period.
The bling aspect of this flow is that it is Alexa enabled!!! Alexa responds to the following commands:
Alexa, inverter on
Alexa, inverter off
Alexa, inverter status
Alexa responses OK to the off and on commands. For the status command it says OK and then does an announcement with the current status.
https://www.crystalpoint.com/cpdownl...tatusAlexa.jpg
When it automatically shuts down the inverter; it does another announcement "Ding, message". On my Alexa show it also shows the text besides speaking it.
https://www.crystalpoint.com/cpdownl...flineAlexa.jpg
Note: Since all your Alexa devices are in group. I can command things to happen on the bus while I am at home...
DIY Hydronic system Engine Preheat
It's starting to get colder here in the northwest, so the bus is doesn't immediately start when you crank it.
So I am starting to test the preheating side of my DIY hydronic system. Here's a run from this morning.
It was 34 degrees out and I was thinking definitely time for a preheat. However I have been also working on solar panel installs so have been running the bus twice a day as I have reposition it in the storage yard to get access to both sides of the bus.
https://www.crystalpoint.com/cpdownl...inePreheat.jpg
The engine coolant value is only accurate while the preheating pump is running as the temperature sensor is in the pumping bay and from it's location it also sees a bit of eddie current heat transfer from the glycol tank. So anyway the coolant temperature started at 50 degrees and rose by 18 degrees in 30 minutes.
Electric Preheating Vs Diesel
Did another baseline run this morning with electric vs diesel boiler preheating.
I have just about finished my solar install project with seven out of ten solar panels hooked up and it was forecasted to be sunny today (no evidence of it yet LOL!).
So anyway I needed to apply a dump load to drain the house batteries to make room for the solar power input.
It turned out to be a colder morning, forecasted to hit freezing tomorrow.
So anyway I turned on the electric heaters in both of the glycol storage tanks and was drawing about 3.4KW of power from the house battery bank for a bit over an hour.
At that point I turned them off and fired up the diesel boiler, which you can see from the red line that I drew on the chart.
https://www.crystalpoint.com/cpdownl...icVsDiesel.jpg
The initial dip in hydronic output temperature is due to diverting glycol back to the diesel boiler at the rear of the bus.
As you can see both curves steepened as the Diesel boiler is a 10KW unit.
Solar panels are mounted!!!
Just finished a big project mounting the solar panels on my bus. I would say I averaged one panel a day for the installation as I was doing it by myself.
I installed ten LG375N2W-G4 panels on the top of my forty foot bus. These panels are 375 maximum watts apiece.
Here's the head on view from the front of the bus:
https://www.crystalpoint.com/cpdownl...SolarFront.jpg
Here's a view looking back along the top of the bus:
https://www.crystalpoint.com/cpdownl...larTopView.jpg
Here's a side view of the first three panels:
https://www.crystalpoint.com/cpdownl...arFontSide.jpg
In this view you can see that the first two panels are mounted in a slope for hopefully a little bit of aerodynamics though I know that this is probably a dead zone given the almost flat front ends on our buses.
This arrangement only adds about an inch to the clearance height of the bus. I didn't continue with the panels going straight back so as to give the air-conditioner hot exhaust a chance to go upwards and not heat the following panels which would affect their efficiency.
Given the poor aerodynamics of our buses all reports that I have heard is that there is no change in fuel efficiency for mounting solar panels. I don't have a base line on this bus, though the previous owner reported 9 MPG; which given his other statements I would discount.
Here's a side view of the last seven panels:
https://www.crystalpoint.com/cpdownl...arBackSide.jpg
Note the very last panel behind the rear air-conditioner is also mounted low to allow the hot air to raise.
I think a nice side effect of this arrangement is that the roof will be shaded and the solar panels should have good airflow to help cool them. Also most of the rain will hit the panels and then run off the sides.
DIY Hydronic system heater core's fan change over
Well hey the bus now has heat since I got the zone fans working!!!
The bus was previously setup with each heater outlet having it's own manual fan control switch, can't have that with my automation/smart bus goal LOL!!!
Anyway I decided to change out the old fans with Noctua NF-F12 iPPC-24V-3000RPM Fans.
In the PC world Noctua has a great reputation for quite and long lasting fans. I went with 3000RPM fans for when I need maximum air movement.
This series of fans have what is called a four wire interface where the fan's speed is controlled with PWM (pulse wave modulation) signal.
The four wire interface has the following wires:
1. Ground
2. Power
3. PWM control
4. RPM feedback signal
https://www.crystalpoint.com/cpdownl...FanControl.jpg
I don't use the RPM feedback signal in my configuration.
In my DIY hydronic system I have multiple heat zones in the bus, with control of each zone done by switching the power on/off for the pump and the fan associated with the zone.
My bus automation controller is Raspberry Pi 4 running NodeRed. The Pi has two pins that can be assigned to do PWM under hardware control. However only one pin can be used at a time for PWM.
Given this I currently have the PWM control line shared by the different fans in each zone. I could add separate cheaper Raspberry Pi's and have each zone be adjustable.
The initial NodeRed flow that I created is very simple.
https://www.crystalpoint.com/cpdownl...FanControl.jpg
It consists of just three function nodes:
1. Set initial msg.payload on startup to 50 which means 50% fan speed. (Note I took my snapshot after I manually set the speed to 100%.)
2. GUI slider control that allows the user to change the speed on the manual control web page.
3. Generate the PWM signal on the GPIO12 pin.
This is just my starter flow it will get a bit more complex when I add voice control via Alexa. I might also add logic to run the fans at full speed if the delta to the target temperature is greater then ten degrees.
If you are not doing automation you can purchase cheap add on PC fan controllers that you can manually adjust, otherwise when you give these fans power they run at full speed.
Another attribute of Noctua fans is that you can set the PWM duty cycle to zero and the fans turn off. Not something all generic PC fans can do.
Anyway it was easy to change out the fans. Here's the old fan:
https://www.crystalpoint.com/cpdownl...aterOldFan.jpg
And the new Noctua fan:
https://www.crystalpoint.com/cpdownl...aterNewFan.jpg
Actually this last picture show's me accidently installing the fan backwards, opp's!!!
Test before you close up....
Solar panel install adventure part one
I thought I would post about my adventure in getting the solar panels mounted on my 1980 Prevost bus.
I guess the moral of this story is to use the proper tools!!!
This adventure was delayed as I thought I would have to bend offset brackets and was figuring out how to get them bent correctly as I thought the length of my panels was less than the width of the bus. It was a measurement error on my part as I used a two by four that was close to take initial measurements. I should have boosted an initial panel up to the roof for a more accurate measurement. By totally serendipity the length of the panels (77 inches by 40 inches) exactly matched the mounting points on my bus!!! So no need to bend brackets!!!
Anyway here's a picture of the offset brackets that I so proudly made to mount the first solar panel at the rear of the bus.
https://www.crystalpoint.com/cpdownl...setBracket.jpg
Using a bench vise you have to plan the order of the bends based on the distance between the top of the vice and the space to the draw bar. I used a vise mounted four inch metal brake from Harbor Freight.
https://www.crystalpoint.com/cpdownl.../paintLine.jpg
Like I mentioned earlier the my solar panels LG375N2W-G4 were an exact fit to use flat plates as standoff's on my bus. The previous owner had a very accurate paint line that was I able to key off of when installing these supports. The roof structure on my bus is aluminum sheets installed over a metal frame. This results in a hollow square tube that I could drill into to install rivnuts for mounting the panels.
Drilling through aluminum and then steel rapidly wore out my drill bits and I kept having to buy individual bits until I broke down and brought a drill sharpener. Nothing worse then being at the top of ladder and having dull tools to work with!!!
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
I was working alone so the next item on my learning list was how to get the panels properly into position!!!
https://www.crystalpoint.com/cpdownl...kingPanels.jpg
I started off using wooden blocks that I had on hand, however this lead to a comedy routine of going up and down ladders repeatedly on both sides of the bus. Which had friends commenting "hey have you lost weight?" to which I would say the answer was yes, lost count of the number of times I have been up and down those ladders!!!! The solution was to get light weight jack stands to accurately position the panels before starting to drill.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Speaking of ladders and proper tools. I initially started using an extension ladder that I had split into two pieces. In the case of my ladder this results in one piece missing a rung which I came very to regret as I had to position a step ladder next to that section to get past the missing rung. I just bet you can see this coming, but at the end of one day I forgot about the missing rung and wound up ringing my chime on the pavement!!!! I also sprained the thumb on my right hand which is still bothering me three weeks later.
https://www.crystalpoint.com/cpdownl...NewLadders.jpg
Needless to say I broke down and immediately purchased a telescopic extension ladder for the bus.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
I have also purchased a number of thick kneeling pads for use around the bus and have zip tied one permanently to the ladder to protect the paint when placed on the bus.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Enough for today, will do another post of consumables that I used to mount my panels.