Power Updates – Out with four separate battery strings and in with one combined system

Rework – .Reconfiguring four separate solar panel arrays, four separate controllers, and four separate batteries into one single array, one new controller —combining the batteries on one bus bar produces improved performance.

Finished product display looks this, a very easy to understand user interface from Victron.

 

Two Steps – Paralleling batteries, then replacing solar charge controllers.

In the past, with four separate power lineups, one or the other was frequently running down or malfunctioning. By combining the components, reliability is expected to increase. Step one was to combine the various LifePO4 batteries into one battery with a bus bar. Combining different age and different capacity cells is allowable with LifePO4 (see sources in Bibliography). Their voltages change so little over their discharge curve and their life span that they don’t fight each other like lead acid batteries do. Often bus bars are rectangular copper or aluminum bars. In this installation 1/0 copper welding cable was chosen instead solely because it’s so much easier to bend. It has a nominal ampacity of 150 amps, similar to a rectangular bus bar. Each end of the cable has a terminal block where the components are connected to the bus bar. In the pictures, first is the north end of the bus bar, then the south end. The ends are about 8 feet apart.

Although it’s hard to tell in these pictures, the load and charger leads are connected in opposite corners of the bus bar to equalize the load and charge for the batteries. If the leads were connected at the same end of the bus bar the closest battery would get over exercised and age faster. The clue in these two pictures is that in one picture there are more positive (red) cables connected. In the other picture, there are more negative (black) leads connected.

Step two was to replace the four existing controllers with one larger capacity controller. This provided a good chance to upgrade to more features and a better user interface. The brand chosen is Victron Energy. Efficiency was also improved by changing from PWM to MPPT. The new controller needed to handle the voltage from combining the arrays and the additional current from the combining.  The model chosen is the MPPT 100|50, which maxes out at 100 volts and 50 amps. The panels are wired to put out nominally 24 volts and 36 amps. A Victron Cerbo GX interface was added to provide Internet access for monitoring and configuration. Older Victron components are already on site accumulated over the years — a 24volt to 12volt 70 amp buck converter, a 250 watt 24volt to 120vac inverter, a 3000watt 24volt to 230volt inverter, and finally a BMV700 battery monitor. All the Victron components communicate with each other using a simple data cable, allowing the GX to show all sorts of information graphically and remotely as in the photo at the top. Below is a shot of the new GX and MPPT controller.

 

Conclusion

The project was completed by dressing the cables and mounting the components on better back boards. It looks like this is the final design and although it has only been running for a few days, no issues exist. A few issues occurred and were easily resolved. Victron products are very elegant but sometimes confusing to configure. Sooner or later everything fell into place. Today, a January day about a month from the winter solstice, where the batteries had been discharged by yesterday’s and last night’s radio operation, charging only took one hour and ten minutes. That is much faster than the old PWM charge controllers. As for reliability, time will tell. Watch for updates. One of the nicest consequences of this project is getting rid of all the cludged-together hardware and software to keep the old system running. That includes the Node Red backdoor Raspberry Pi’s and the APRS status transmissions. This new system is so reliable so far that none of that 3rd party monitoring stuff is needed.

Bibliography

Sources to support this project: – A source to validate dissimilar LiFePO4 batteries can be safely connected in parallel is below from DIY Solar.

Off-Grid Garage has also been found to be a good source for all sorts of Victron Energy information needed for configuration and testing, as has DIY Solar.

Victron settings came from Off-Grid-Garage video “How to set your MPPT Solar Charge Controller for LiFePO4 batteries”. Key settings:

Absorption voltage: 3.45 V per cell or 27.6 V for the W0QL 24 volt system

Float voltage: 3.35V per cell or 26.8 V

Absorption time: 1hr (W0QL went to 1:15)

Tail disabled

The settings are posted on the Off-Grid-Garage website:

My Settings

New Thoughts On Grounding

Specifically, grounding for the DC circuits, and why is equipment being damaged?

It’s been 6 years since the last article on this blog about grounding. No damage from lightning (knock on wood) all these thunderstorm seasons later, is a good testimonial to the lightning ground. However, lately a few devices have been destroyed or damaged not by lightning but by something else. Considering there have been no thunderstorms the damage probably has been caused by voltage spikes from somewhere. But from where? A ground loop? A relay with no diode? One inadvertent source of a ground loop has been discovered. The negative side of the DC power bus has been connected to the Single Point of Ground since 2017. No noticeable problems have been observed due to this, probably because of luck.

Dereck Campbell, KF5LGW, has a good explanation of why connecting the two together is a bad idea. Note that Dereck is talking about an AC to DC power supply and the remote system has only a DC battery supply. Read around the references to AC line in the explanation below, please. Pay attention mostly to the right hand side of Dereck’s drawings.

The objective is to isolate AC and DC power systems and remove your radio equipment from the ground loop by relocating the ACEG to the same point the shack uses. To understand what is happening, let us draw the circuit out and see what is happening.

FIG 3A shows how 2-wire and 3-wire systems are incompatible. Look closely at the 2- wire system chassis (ground) and DC Negative circuit conductor and the same conductors bonded together inside your 12-volt radio equipment. That is not compatible with 3-wire systems. As you can see the red arrows result forcing normal DC operating current on ground conductors.

The result is DC flowing on equipment grounds, coax shields, and GES. Look what happens when I induce the same AC Line-to-Ground fault inside the DC power supply in FIG 3B. Follow the fault current paths like before. One path is on the ACEG conductor like you planned, and the other unplanned path goes through your radio equipment needlessly and can cause significant damage to your radio equipment and coaxes.

Take note. The 14 AWG ACEG conductor from the breaker panel to the wall outlet can be 30 to 100 feet in length. The unintended secondary path created is through your radio equipment using a 6 AWG conductor of approximately the same distance going back to the same point as the 14 AWG. They are in parallel. Which of those two parallel paths do you think will carry the bulk of the fault current? The 6 AWG or 14 AWG? All you need to know is how Ohm’s law works; no math required. Isolate the 2- systems, and you eliminate the problem!

Lost in a ground-loop creates two more issues. One a minor annoyance generating RFI/EMI. You have a piece of wire (you radio ) bonding the two ground electrodes together with a common-mode current flowing through your EGP. The second problem can be extremely hazardous if lightning strikes nearby. Equalization current path is right through your equipment, acting as a piece of wire.

Now, look at Fig 4A and Fig 4B. I removed the bonding jumper hiding inside the DC power supply. Follow the red arrow current again. What happened? AC and DC systems are isolated. No DC is flowing on any ground conductors. Removing the bonding jumper broke the DC galvanic bond across the transformer inside your DC Power Supply. AC and DC systems are isolated, allowing you to interface your home 3-wire system to your radio’s 2-wire system. The DC system can be a Grounded System, but do not use your DC power supply chassis ground because the transformer’s primary side is part of the AC system, including the chassis.

Why Is Equipment Being Damaged?

One possible explanation is the DC negative bus being grounded but that hasn’t caused known issues for many years. Could the damage be from “back-emf” from an inductance? When a relay is activated and then eventually deactivated there is a voltage spike from the coil which is back-emf caused by the inductance of the coil. A diode across the coil will short-out that back-emf voltage spike. There are several high amperage relays in the remote station that have large coils and large voltage spikes. Those relays all have diodes installed and it is unlikely those relays are the cause of the damaged equipment. What has changed lately is the West Mountain Radio 4005i power controllers have been replaced by a KMTronic 8 relay unit and a DC power strip. In the past, each device was powered individually by a port on the 4005i’s. Instead, now several devices are lumped together and get their power from the DC power strip through a relay on the KMTronic. Power to that strip is turned on and off by the KMTronic unit. Some of the devices are in the shack and others are out at the end of long runs of power cable. In-the-shack devices are in parallel with those long cables on the DC power strip. One tuner is 100 feet away and one security camera is also 100 feet away. That long cable may have enough inductance to induce a back-emf voltage spike when the KMTronic deactivates it’s relay. The plan is to add 1N4001 diodes across the long cables and then to add 14 volt Zener diodes across the inside-the-shack devices. It is hoped the diodes will provide protection from spikes and stop the damage to equipment. Or isolating the DC negative leads from the green-wire ground bus (single point of ground) will. Updates to come.

Node-Red Aux Dashboard – Part 1

This dashboard project is for the following purposes:

1. Improving performance of the heaters on the batteries.

2. Reducing RFI from the solar panels.

3. Displaying status such as the Flexradio final transistors temperature.

Hardware is a Raspberry Pi 4 located at the remote site, connected over the LAN to Web relays.

Modbus

The flow first polls Modbus data from the solar controllers and in turn performs actions like closing relays. A Node Red flow polls the modbus, then converts the modbus floating point data to readable decimal, and finally, turns relays on and off. One feature improves the battery heater operation by bypassing the thermostats as needed. Another feature reduces RFI by disconnecting the solar panels from the solar controllers when batteries are fully charged. The most difficult task so far has been converting the floating point data to decimal. That flow is what is discussed first.

Data from the modbus is in the format of IEEE 754 half precision 16 bit floating point Little Endian which is unreadable by humans. Many JavaScript functions are available to perform a conversion operation but they have all proved impossible to implement during this project. Thanks to chatGPT a solution was finally implemented that works. It took 7 iterations of chatGPT to develop a Node Red function node which produced the correct output and no errors. The successful node is shown below to get it down on paper for preservation.

It was a huge milestone to get the floating point conversion node working. Below is what the output of the big achievement looks like. The number is the actual voltage of the 24 volt battery as measured by the solar controller and processed by the Node Red flow.

It’s easy to confuse the use of the word “function”. To offer some clarity, the node above is a Node Red “function” node. Inside this function node is a JavaScript “function”. The JavaScript function is the first thing in the node. The JavaScript function is declared and defined, making it ready to be used. Next element is at the bottom and that is where the JavaScript function is called, data is passed to it, and the output is moved into the msg.payload object.

The Flow

The object is passed to the next Node Red node which is a debug node (debug 22).

On the left above is the Modbus Read node, named Stras 88. It’s settings are shown below.

In the Server field above, the name is Stras 88 which indicates the location of the solar controller and the port number. It’s I.P. address is entered by clicking on the pencil icon on the right. The Address in the Address field is obtained from the Morningstar documentation. The FC field is always FC 3 when reading a holding register per the Modbus specifications.

A big project has begun. Onward to the next part, the outputs.

OUTPUTS

Microbit RemoteRig 1216H Webswitch relays will be used because they are already in place from an earlier project. See https://w0qlremotebase.wordpress.com/2021/05/01/noise-chase/.

These relays are currently wired up to remotely turn on and off the solar panels from the solar controllers manually. Despite mechanically working perfectly, turning on and off the relays manually did not happen. Too much work? Along came Node Red and this function can now be down automatically. First, the command set for the 1216H is available on the Webswitch website and also posted elsewhere in this journal: https://w0qlremotebase.wordpress.com/2023/02/12/microbit-remoterig-1216h-webswitch-command-set/

TESTING

In Node Red a node called EXEC can be used to execute a command. The command can use curl to send a web request over the internet to the 1216H, and the response will be the status of that request. In the flow below, an http request is encapsulated in a curl command in an exec node:

The configuration in the exec node is shown below, with a fake I.P. address. Enter your own here.

In the next chapter some nodes will be wired together in such a way as to turn off the solar panels when the battery is fully charged and RFI is occurring.

Step 1 is to do a modbus read of a solar controller looking for the High Voltage Disconnect (HVD) bit. Morningstar controllers have this feature when using Lithium batteries. When the HVD bit is positive, tell the 1216H to close a relay corresponding to that controller. The closure in turn opens a higher current relay and disconnects the panels. Boom. RFI stops.

Noise Chase

For a long time there have been multiple signals on this remote base that appear to be digital hash and not legitimate radio signals. On the water fall they look like noise from switching power supplies. Considerable work has been done trying to get these signals chased down. Over the last year each switching power supply has been replaced with a linear supply or the switching power supply has been mounted in a metal box with ferrite chokes on the leads. Since the noise continued, looking elsewhere was necessary. The next suspects are the solar controllers considering they switch power on and off rapidly just like a switching power supply and considering they are about the only devices that haven’t been investigated. Searching the web turned up numerous reports that solar controllers are major contributors of rfi. The controllers used at the remote site* are specifically selected because of their FCC Class B certifications. They aren’t supposed to be generating rfi. That’s why they haven’t been investigated earlier. Today’s testing was very revealing. The controllers are generating tremendous rfi. Later it was discovered the interference occurred only in the mode where the batteries are fully charged. The controllers are in a state of “high voltage disconnect” to avoid overcharging the LifePO4 batteries. When the system is in a charge state there is no interference. Below is a picture of a water fall on 17 meters on a sunny day when the solar system is generating full capacity in a “high voltage disconnect” status.

Obviously those big wide bands of yellow-green are not supposed to be there. They are digital hash caused by something. Their huge signal strength indicates the source is probably local. Next picture is with one of the four controllers turned off. Observe the band on the right and the band in the center have disappeared as the waterfall continues to scroll down. Two bands on the left are still present.

Next, another of the controllers is turned off revealing an amazingly rfi free band. What a stunning difference. Apparently the other two controllers are not generating hash, for some reason yet to be determined.

Toroid chokes on the controller wires should be an easy fix. A hand full of Mix 31 ferrite toroid chokes was placed on the wires that come in and out of the controllers and no noticeable change occurred. Paraphrasing the captain of the boat in the movie Jaws, “We’re going to need a bigger choke”. Upon more Web scouring back home, an article was found that discussed a rarely mentioned bit of information about ferrite chokes.

“Ferrite material choking performance degrades in the presence of strong DC current. For this reason, it is better to pass both DC wires from the solar panels through the same snap on ferrite as this will eliminate the DC bias in the core.”

The chokes had been placed on individual wires in the initial test. About 15 amps of DC was present on those wires. Is this DC current enough to degrade the performance of the chokes? On the next trip to the site, both wires will be placed through the cores and the results will be reported here.

*The controllers used at the remote site are Morningstar PWM ProStar PS-30 and Morningstar MPPT ProStar PS-MPPT-25M.

Chokes On Both Wires Together

Next site visit and the first thing noticed is that different controllers are causing interference than the ones that caused it last time. Here is the first picture upon walking in the door without any testing.

Two lines of digital hash coming down the waterfall are from two of the four controllers, but not the same ones as last time. Next picture is after turning off three controllers and at the 7 second mark placing a choke on both wires of the 4th controller.

The choke clears up a good amount of noise but not nearly all of it. More chokes were added and there was almost no more improvement. Chokes don’t seem to be the answer.

Next topic is why only two controllers at a time cause interference. What is the difference? PWM and MPPT controllers are both contributing equally. It was soon noticed that the interference is coming from the controllers where the batteries are fully charged. When a battery is not fully charged and the controller is working hard there is no interference. When a battery reaches it charged state and the controller stops charging, it starts generating the digital hash. Solutions come to mind both elegant and crude. An elegant solution would be to monitor the modbus data output and watch for the fully charged messages. Use a microcontroller like an Arduino to turnoff the controller. That sounds like a lot of coding and debugging and time spent. Turning to the crude solution, that would be a relay on the solar input cables driven by a voltage sensor on the battery. When the battery reaches full voltage the relay would open and effectively turn off the controller. Call this solution the Rube Goldberg, band-aid, patchwork-quilt solution but voltage sensors and relays are now on order from China. The interference will have to be lived with for a month until the parts arrive.

While waiting for the parts from China an article surfaced that suggested trying 4 turns of both wires through one toroid of mix 31. That was tried and it did not reduce the noise noticeably.

In an act of desperation bypass relays were inserted in the solar panel input leads so each of the panels could be cut off completely if they were causing interference. This is the method referred to above as “Rube Goldberg”. The difference is the relays are controlled remotely from home over the Internet instead of by an Arduino monitoring the modbus or instead of a voltage detector. So far it works perfectly. Case closed. For now.

Update February, 2023. Along came Node Red and big improvements have been made. Go To

Node-Red Aux Dashboard – Part 1

Lithium Batteries In a Non-Heated Environment.

When LifePO4 batteries are located in an unheated outdoor equipment shed in climates like Colorado their winter temperature can fall below freezing quite often. LifePO4 batteries will be damaged if they are charged when they are colder than freezing. A couple of uninviting options exist. First, the shed can be insulated and heated, which could be a lot of work and expensive. Second, the batteries could just not be charged until the temperature warms up. Even on a sunny day that typically means around noon and leaves only time for a partial charge on short winter days. A third option appears to be the least painful and that is to provide some external source of heat directly to the batteries through the use of heaters. There doesn’t seem to be any product marketed specifically as a LifePO4 battery heater. Researching alternatives, one possibility is the silicone heaters used to warm the bed of 3D printers. It is flat, comes in various shapes, voltages, power ratings, and it is inexpensive. A sampling was ordered and tried out. Finally selected is a 20 watt 12 volt heater shown below.

These pads fit nicely between alternating cells so each cell is adjacent to one heater. Leads are brought out and connected in parallel with wire nuts. Each heater draws 1.5 amps and in the lineup below 4 heaters draw 6 amps.

Getting this far was the easy part. Figuring out how to power the heaters is the next challenge. It was quickly learned that using the batteries themselves was a net negative. Heaters use too much power. The batteries don’t get fully charged before the sun goes down. An external set of batteries was tried but that just shifted the problem. After a few days the external batteries don’t have enough charge to run the heaters. Another failure was the use of timers to only turn on the heaters right before the sun came up. A new idea was needed. Time for …

Innovation

While the batteries are too cold to charge and the heaters are running, the solar cells are sitting idle wasting generated power. Why not use that solar power to run the heaters? Duh. This idea was tried and has been working successfully for several cold winter months. Power was tapped where the solar panels go into the solar controllers. The tap is the small red and black wires in the picture below.

Raw voltage from the panels is typically 20 volts and that might burn out the heaters. A 10 amp buck converter was inserted in the line to keep the voltage at 12 volts, one buck converter for each of the battery banks. A metal box limits the rfi emitted from the digital buck converters.

Update – January, 2024:

The buck converters in the picture below died in the summer months (capacitors failed). Golf cart dc-to-dc converters were used to replace the old units. The new converters are encased in their own metal shell making the enclosure below unneeded.

W1711 thermostats round out the installation. These little guys are set for 5 degrees Celsius which allows some margin to make sure the batteries are kept above freezing when the sun is up. When the sun isn’t up there is no concern because there is no solar power available to damage the batteries. What happens when there is solar power but the batteries haven’t warmed up above freezing?

The Morningstar controllers were specifically chosen because of their feature called “low temperature fold back”. Even when there is solar generation, if the batteries are below freezing the Morningstar controller will refuse to charge the battery.

Update – January, 2024:

Morningstar controllers were replaced with Victron Energy controllers and batteries were bussed together in parallel. See https://w0qlremotebase.wordpress.com/2024/01/26/power-updates/

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Insolation Monitor Project

Insolation is a big word meaning how much sunshine is there? That’s an interesting bit of information when one is trying to keep batteries charged with solar panels. It’s just a cross check to see if the charge amperage is consistent with the amount of sunshine each day.

The project consists of a photo cell and an Arduino-emulation device called a ESP32. The hardware looks like this. Very minimalist. The breadboard is just to hold the ESP32 in place. A USB cable brings in 5 volt power. The round disc is the photocell.

The ESP32 connects to the Internet over wifi and uploads data every 10 seconds using the protocol MQTT, “the standard for IoT messaging” . Data consist of the resistance of the photo cell. A server processes the data and provides a web page GUI. The server is called a broker and in this case the broker is provided free for personal use by Adafruit. The ESP32 is also a product of Adafruit. The ESP32 cost $20 at Microcenter.

Below is a screenshot of the GUI page, putting it all together.

Ideas for the next version: Mount the ESP32 inside a solar powered yard light and eliminate the USB cable. Disconnect the light and power the ESP32 instead.

For a closer look the link is here:

https://www.amazon.com/gp/product/B07ZSC6TNB/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1

This solar powered led yard light was chosen at random and it was chosen for it’s reasonable price. When it arrived it looked like this:

Opening it up revealed a pleasant surprise which had not been mentioned in the sales description. It has an actual 18650 lifepo4 battery. Perfect. This battery should power a ESP32 for many hours. The ESP32 draws 100ma at 5 volts which is one half watt. The 18650 is rated at 4.4 watt-hours (4.4 watts for an hour). That would be 4.4/.5 or 8.8 hours. In reality that time would be extended by the ESP32 going into sleep mode when it’s not sending data. It would never need to send data constantly for 8.8 hours.

Unfortunately the controller board that comes with the unit will have to be discarded because it doesn’t have the features needed for the ESP32.

Will the ESP32 fit inside the waterproof cabinet? Looks like it will.

In fact, a LORA board will fit very nicely, too, and that can come in useful for the next project, building a LORA network.

Reading up on how to power a ESP32 from a solar yard light has revealed some challenges but also solutions. First, the cell voltage is 3.7 as can be seen in one the pictures above. The ESP32 needs either 5 volts or 3.3 volts, neither of which is close to 3.7 volts. What is needed is either a boost converter to get up to 5 volts or a buck converter to get down to 3.3 volts. The battery voltage of 3.7 is nominal. The voltage can vary from 4.7 to 3.2. When it’s 3.7 or above the buck converter works fine but when the voltage drops below 3.7 the buck converter shuts down. That rules out the 3.3 volt option. Looking at the 5 volt option, there is a possible solution. Connect a standard charge controller between the solar panel and the battery such as the TP4056 Charging Module 5V Micro USB 1A 18650 Lithium Battery Charging Board with Protection (5 pieces for $5.95 on Amazon) which looks like this. It’s output will vary with the voltage of the battery.

Boost converters exist ($7.29 for 5 pieces on Amazon) that will provide a constant output of 5 volts with an input as low as 1 volt or as high as 5 volts and look like this.

The concept is the charging module will regulate the solar input to keep the battery properly charged. As the battery charges and discharges the output voltage will vary. The boost converter will take that varying voltage as input and it will output a constant 5 volts.

Moving on to the next step, those parts will be ordered today. Total additional cost $2.86 per unit.

Amplifier and Inverter

Project 1 of 7 for 2020

This project has been completed. See “1.5 KW Amplifier Off Grid” https://w0qlremotebase.wordpress.com/2020/10/14/1-5-kw-amplifier-off-grid/

A new amplifier is on order and installation parts are arriving. The good ole SG-500 gave up the ghost and besides it didn’t have 6 meters. Good excuse to look around for a new amp. Deciding on which amplifier to chose was a tough decision because many fabulous new amps are on the market today with 6 meters and great new features. The decision was made easier because one amp looks like it was designed from the ground up to integrate with the Flex. It is the 4O3A PowerGenius XL, or just PGXL for short. Good experience with another 4O3A product (the Antenna Genius) is a strong selling point. A PGXL is on order from Flex.

Going from the 500 watt SG-500 to the 1500 watt PGXL requires some power improvements. A new amp cannot be run on 12 volts. It was decided to add a separate set of batteries, an inverter, and to go to 24 volts and stay off-grid. The existing 12 volt off grid solar system will stay in place untouched for use by the existing 12 volt equipment. The hope was to go all the way to 48 volts for efficiency but no solar controller could be located that would provide low temperature foldback. Foldback is important because it reduces charge current when the temperature is below freezing. The Morningstar ProStar 30 currently in use on the 12 volt system does provide foldback and it works for either 12 volts or 24 volts. Thus the decision was made to run at 24 volts to make sure the batteries are protected in the winter. It takes big wire to carry the 200 amp current needed. The inverter manufacturer recommends this 1/0 cable to run between the batteries and the inverter.

Deciding on an inverter was also a tough decision because there are a lot of fabulous looking inverters on the market. Hybrid means the inverter is combined with a solar controller (charger) in one cabinet. The new so-called hybrid inverters would simplify things but none could be found with temperature foldback. Two more must-have features limited the choice greatly. First, the inverter must have FCC Part 15 Class B certification or equivalent. Inverters are notorius for generating RFI and presumably an FCC certification will fix that. No China inverters have certification. The other must-have is pure sine wave output. That’s pretty easy to find. Output voltage is also important because the amp can’t run full output power on 120 vac. It must have “220”. That number is in quotes because it is has become a generic term to describe 230 volts in some countries and 240 volts in the United States. Since the amp was made in Europe it will be quite happy with 230 volts. There is no neutral wire on European circuits. No 120 volt appliances can be run from this inverter. The inverter that was decided upon and is on order is the Victron Phoenix Inverter Smart 3000.

. A week later the inverter has arrived and is unboxed, looking like a work of art. It is 24 volts in and 230 volts 3000 watts out.

Victron recommends using 1/0 wire for this model between the battery and the inverter. That is the largest wire ever used at W0QL and a new crimper had to be obtained along with terminal lugs for 1/0.

A closeup look at the crimps with heat shrink tubing installed.

Mounting the inverter was a piece of cake.

Lugs are easy to reach.

The very first cable attached was the green wire ground. This wire runs directly to the copper ground bar which is bonded to the ground ring around the shed.

The 1/0 cables were bolted and strapped in. One more stage is finished and ready for the next equipment to arrive: the batteries, the BMS, and the AC power parts. A 250 amp fuse is midway down the battery cables. At the lower right is the terminal block for the cables from the BMS. One thought is to replace the terminal block with current shunt from another Victron Coulomb counter battery monitor. No decision has been made. The batteries will go in that big bare spot on the floor.

Current status: Amplifier shipped last week, has arrived in UPS facility in Denver, awaiting delivery Monday or Tuesday, September 22, 2020. Batteries are still off shore or in Customs.

Amplifier arrived but no place to plug it in yet. Batteries have still not arrived in the States.

A decision was made today to temporarily borrow half of the cells currently in use for the 12 volt system and rewire them for 24 volts until the permanent batteries come in. On the floor is the borrowed temporary 24 volt battery pack. This pack provides 100 AH which is enough for testing at moderate RF power levels. It is being charged by four 12 volt solar panels connected in series-parallel to provide 24 volts nominal. BMS? A 24 volt 8s 100 Amp BMS was found in the junk box and put to work.

With this pack the inverter powers up perfectly and provides it’s default voltage of 230 volts AC.

The amplifier is on site for testing but not in it’s permanent place yet.

It is rather massive and needs a little more space cleared out before it can be completed. Initial tests are amazing. Antenna and feed from the transceiver are the only connections to the Flex 6600. All control, CAT, PTT, and ALC signals are over the LAN. Upon firing it up the amp found the radio automatically. Like people say, the operation is so slick it just acts like a bigger front end for the radio. No tweaking or peaking needed nor bandchanging. The amp follows the band on the radio transparently. The operation is just amazing. Testing with the temporary battery the amp was given 10 watts RF input. Output was 350 watts. The inverter reported a drain of 1000 watts. With no way of measuring the battery drain it looks like another Coulomb counter is in the future. The inverter can display instantaneous battery load but not the capacity remaining. This is a learning experience.

This project has been completed. See “1.5 KW Amplifier Off Grid” https://w0qlremotebase.wordpress.com/2020/10/14/1-5-kw-amplifier-off-grid/

From Lead Acid to Lithium

The original golf cart and deep cycle marine lead acid batteries didn’t seem to have the oomph they once had.  They are running down too quickly and are getting harder to recharge even though they are only 2 years old.  Batteries Plus tested a couple of the golf cart batteries and said they had about a year of life left.  They tested by drawing 125 Amps for a minute on each battery.  Those results were an inspiration to look around for new batteries.  Upgrading to AGM batteries would cost $1600 (from a dealer quote in Denver).  Then a YouTube video was discovered about LifePO4 lithium iron phosphate chemistry.  See Will Prowse the DIY Solar master at https://www.youtube.com/watch?v=zStEtH9Le-w&t=241s

Four LifePO4 100AH cells were purchased on eBay along with a BMS (Battery Management System) in an attempt to move up the learning curve and find out if LifePO4 would be a good upgrade.  In ensuing months it was learned that there is a lot to learn.  Lithium chemistry is far superior to lead acid for a solar application but there is a learning curve.  For example, LifePO4 batteries can not be charged if the temperature is below freezing.  That’s a significant hurdle for an outdoor storage shed on the Colorado plains.  After a month of use and several paradigm changes the Lithium batteries are proving to be a great upgrade.  One advantage is the space saved with Lithium.  Compare the Lithium sitting on the shelf (green) to all the lead acid batteries on the floor it replaces.

The solar controller was replaced with a model that was designed for Lithium charging, which is a Morningstar ProStar.  In addition a second order of 4 batteries was added for a total of 200AH rated capacity.  Heater pads (12 volt, 25 watt) were place between the cells with a thermostat set to 5 degrees Celsius.  Two autumn frosts have occurred and the heaters have kept the batteries above freezing.  As of this writing the ambient temperature is 1C and the battery temp is 6C.  Will they hold up over the cold winter ahead?

Followup after a snow storm and 108 hours below freezing at the end of October:  Yes, the heaters kept the batteries warm.  However, the Lithium did not have enough power budget to supply the heaters, the radio equipment, and the computers along with snow on the solar panels.  A low voltage disconnect occurred causing no damage but the station was off the air.  The heaters and the computers were moved back over to the lead acid batteries to get back on the air during the storm.  To avoid spending any more money this hybrid arrangement will be used for a while.  Long term solution is more Lithium batteries.

End of Wind Turbine Experiment

The wind turbine experiment came to an abrupt end during a thunderstorm when the flange came loose.   The turbine flew off it’s mount and crashed to the ground.  All three blades were destroyed, the wind vane was bent, and maybe the shaft was bent.  It is pretty much totaled.

What was learned is that wind can supplement solar but…   Wind produces fewer watts per dollar investment.  Turbine: $300 produces 5 amps on a windy day.   Solar: $300 produces 18 amps on a sunny day.  In other words, wind does work but it’s not an even trade-off.  It was a fun experiment and provided a lot of new knowledge.  This turbine will not be repaired.  The smaller turbine we started with in the beginning can go back up with minimal expectations.  Better than nothing after dark.  Lesson learned:  Pay more attention to mechanical considerations.

Wind Turbine As A Power Source

Wind Turbine As A Power SourceSolar panels are working great except for nighttime and cloudy days.  To fill in those sags the idea of wind power came to mind.  A video on Youtube by John Daniels was inspiration because John demonstrated that a small turbine can produce as much power as a similarly priced solar array.  The advantage, of course, is that it can do that day or night, cloudy or clear when the wind is blowing .  Here’s a link to the video:  https://www.youtube.com/watch?v=B9e_owv9U7w&t=394s.  Considering a total lack of knowledge of wind power on my part, it’s time to move up the learning curve.

The same turbine shown in the video was ordered from Ali-express and installed on a 10 foot mast.

The bolt-on flange was purchased from Grainger so no welding was needed.  It works.  It holds the turbine secure even with strong winds.  Next task is to attach the blades and raise it.  The finished product looks like this.

As per the video a controller was built from individual components rather than using the lightweight controller that is included with the turbine.  Diode on the left, voltage sensor in the middle that switches the relay in and out, and the dummy load diversion resistor on the right.  Compare all that paraphernalia with the nice compact solar controller below.

One shortcoming is there is no way to monitor the current remotely.  Arduino to the rescue, along with a shunt and a INA219 current sensor interface module.  Two sensors were built so current from the solar array could be compared with turbine current.  Here is the Arduino and it’s peripherals on their way to the installation site.

The remote sensor works great as does the turbine and it’s home built controller.  We’ll evaluate how well the turbine fills in the sags over the summer.  Over the winter is probably a better test, with less sunshine.

The display screen of the Arduino remote current monitor looks like this.  Current A is the solar array and Current B is the wind turbine.  In this example the solar panels are providing 8 amps of current and the wind turbine, about 2 amps.  Naturally, the minus sign means the wind was blowing backwards at the moment.  Just joking.  The positive and negative leads got hooked up backwards and will be corrected on the next visit to the site.