Off-Grid Power #1; Electrical Panel and Generator Control

As we described in This Is Not a Normal House, we live off-grid in the literal sense of not being connected to any fixed utility grid. This means that we generate and store all of our own electricity. In the winter here in the snowy north that means that our 6 kW diesel generator is our prime power source, providing not only electricity to run our appliances, but also charge our lithium iron phosphate (LiFePO4) battery bank. Since we do have storage, the generator does not run full-time. In fact, with 20kWh of battery capacity, we have enough capacity to last for about 24 hours between charges if we really need to do so. However, due to the way that the former home owner designed the electrical system, there are some loads that are “generator only” such as the washing machine and the dishwasher. As you can imagine with a family of nine, appliances like the dishwasher and clothes washer are fairly important, Thus, having a working generator is a high priority here at the homestead.

Our generator is fairly reliable, but as anyone who owns a car knows, engines require regular maintenance. Even so, sometimes, a part wears, a belt breaks, a pump fails. We have had many such instances over the past seven years, and have become fairly adept at performing scheduled maintenance like oil and filter changes (how many other people do you know who can say “I had to change the oil on my house last night?”) and minor repairs. We have also developed a good rapport with the parts and service folks at Alaska Diesel Electric, who regularly go out of their way to supply us with parts, service, and even after hours phone support.

Back in early December, we had some more major work done on the front-end of the engine, replacing the front seals, water pump, and alternator belts. It was more than I felt comfortable doing, not least because we only had about a 12 hour window to be without the generator before the washing would start to stack up and the battery bank begin to get dangerously low. Nate did a great job, and had the engine disassembled and reassembled in short order. When the engine was back in service, however, we noticed that the generator, though turning and producing electricity was not charging our batteries. Even more worrisome, we noted that both the voltage and frequency were fluctuating wildly. We had seen this behavior from time to time, and since it had suddenly become much worse after a major overhaul, I assumed that somehow lifting and moving the engine and generator had caused a marginal part to finally fail. I was convinced that it was the frequency regulator on the generator that was to blame, a fairly expensive part to replace, but it seemed to be the only option, so we replaced it. Sadly, this did not correct the issue. The power still seemed to flux randomly. Finally, Nate noticed that the generator sub-panel was getting hot. After taking the cover off, Nate and I saw clear evidence of arcing.

Nate is a mechanic, and a good one, but not an electrician qualified to work on mains voltage. Furthermore, the electrical system in our house is more than a bit eccentric, even for an off-grid home. As it was unclear if this was just a defective circuit breaker, or something more serious, like a ground fault, we decided to seek professional help in the form of a properly licensed electrician. Josh Foreman, our go-to electrician and contractor was unavailable, so we called a number of other electricians. I am not sure if it was our remote location, the fact that we were off-grid, or the extreme cold weather that we had been experiencing at the time (between -20 °F and -30 °F) but we could not find anyone willing to replace our sub-panel. We did get one electrician out, who simply rearranged the breakers in the panel and said: “It’s working, so it should be good to go.”

Meanwhile, we continued to experience issues, always at the worst times, On Saturday, right as we were about to embark on our three hour drive to Anchorage to attend the Opera, we started the generator and were unable to begin to charge the batteries. We tried a few things in vain, including a quick oil change and flipping the troublesome breaker, until, the voltage again randomly stabilized enough to be qualified by the inverter/charger and start charging the batteries. Sharon called Josh Foreman on our way out the door, and set an appointment for Monday afternoon.

Josh came out this afternoon and, after noting the damage to the bus bar and back of the breaker told us that we were lucky that the defect had not started a fire in our generator room. Given that we have a 500 gallon fuel tank to feed the generator, I cannot even imagine how that would not have been a total loss.

Anyway, Josh did a great job, installing a new sub-panel, bus-bars, and breakers!

But the saga is not over! Oh no! When Josh was done, he went to go start the generator to demonstrate his handiwork. But, not only did the generator not start, the autostart control panel was completely dark. Our first assumption was that we had inadvertently drained the starting battery (did I mention that we have a separate starting battery for the generator?) Ok, no problem, we have a portable battery charger, we will just give the battery a quick charge and be back in business. But when we put the charger on the battery, we were reading a full charge of 13.6 VDC! So the battery was fine. Next we checked the fuses, all seemed to be in order. Josh did not touch the DC control side of the generator, so we really could not figure out what was up.

Now, I should mention a few more details about our system. Our inverter and battery bank is located inside our house. The generator is in our garage, which in our case is detached from the main house. It is still fairly cold, so Sharon lit a fire in the wood stove in the garage to make work a bit more comfortable, as we began to troubleshoot.

Normally, the inverter controls the generator by signaling the Dynagen GSC 300 auto-start controller on the generator to start or stop. The controller then activates the glow-plugs, starts the fuel pump, and cranks the starter. After the engine starts it monitors the sensors on the engine (and the power output of the generator) alarming when ever any of the operating parameters indicates an anomaly, activating safety features if necessary. Finally when it is time to shut the generator down, the controller manages the generator cool down and finally cuts the fuel supply. In short, the controller is the brains.

Our GSC300 came with the generator and so is >10 years old. The display had become flaky and difficult to read, but this did not seem to affect the functionality, so I had just assumed that this was something that we would have to learn to live with until we were ready to upgrade the generator, or at least replace the controller with one that has IP monitoring and control functionality using the MODBUS protocol, such as the Dynagen TG410. This would allow me to monitor the performance of the generator from inside the house, collect and graph performance statistics over time, and even check on the generator from my office in Anchorage. Ideally, I could use tools like Node-Red and Home Assistant to read the MODBUS data from the generator, and possibly from a compatible inverter (and battery bank) and use this data to do intelligent load management and home automation based around battery state of charge, or the fact that the generator is producing excess power.

My hand was forced, however, as the controller appeared to be dead, and I did not have any kind of manual override capability. It was 4:30 and I was not even sure if I could find a drop in replacement for this very specialized part, I certainly did not have time program a more complex unit. I called Alaska Diesel Electric and explained my predicament. Not only did they have a replacement GSC300, but also a manual start/run panel. I asked for both, hoping that I could drop in the replacement controller, but thinking that if nothing else, I could use the manual switches to hotwire, so to speak, the engine so that we could at least generate some power.

I arranged to meet Nate after hours with the parts in Wasilla, and drove the 60+ miles to pick them up. Meanwhile, Sharon opened up the control box, and labeled all of the cables going into the controller. It was a bit confusing because some of the cables in the box were unconnected, and one wire came loose before she could label it or identify where it came from. Even more frustrating, the wiring diagram used a different numbering scheme (numbering connections 1-8 starting at the bottom) than the labeled pin outs on the controller (which were numbered 1-8 starting at the top). Sharon, unaware of the numbering scheme had zero-indexed the wires, starting with 0 as the top connection. But since one wire came loose, and not all 8 wires were connected to begin with, we could not use a simple process of elimination. At some point I realized it would be handy to know the color-codes on the wires, and fortunately for us, Nate was able to text me the color code. Then it was a matter of matching the function identified by color-code with the functions on the wiring diagram. It was not quite a one-to-one match, but close enough.

We plugged everything in and were rewarded with lights on the controller. With bated breath, we pressed the Manual Start button, and were rewarded with a display stating “preheating” and then the engine cranked and we started generating power!

We were elated, but, still need to test the auto-start functionality. After all, if we just wanted to manually start the generator while standing next to it, we could just use the switch panel rather than the expensive and sophisticated GSC300. So Sharon manually stopped the generator while I went in the house to trigger an auto-start from the inverter. No dice. What was wrong? We had no idea, and thought about just calling it a night. Then, I took one last look at the wiring diagram and identified that the remote start contacts were on a molex contact block on the left side of the controller. We opened the control box up and discovered that we had been so focused on the individual wires contacts on the right side, that we had forgotten to plug the molex connector into the controller!

We plugged the molex in and… Everything worked!

Thanks to Josh, Nate, and everyone who put up with our frantic after-hours troubleshooting calls!