A storm was brewing. Sunday was to be the biggest snow storm of the year so far. The grid out here is unstable at best. Weak power poles, high winds and blowing snow all make for power outages. Sure was a good thing we invested in our solar system, especially the battery back ups. I’ve had to use them before and it is reassuring to know that even if the worst blows in and knocks the power out for days, the freezers and fridges will still stay running, the furnace will still heat and the well pump will still pump. That is, of course, if the batteries are working.
Rewind to Thursday. We wake up and do our morning routines. We are having some work done on our bathrooms and we thought that the sulphur smell we were smelling was back gassing from the septic system up one of the sink drains that are being taken care of. Zina leaves for work, I head into town for some groceries. When I got back, I walked in through the back door. By the back door are all of the gizmos and boxes for the solar array, including the PVC vent that vents the hydrogen out of the house when the batteries are charging. Normally this is practically imperceptible. Not today. Today it was BILLOWING smoke out of it. The fan in the pipe was running as hard as it could and it smelled like the aftermath of someone just having shot off a brick of firecrackers. This wasn’t rotten eggs, this was burning sulphur.
Stunned, I ran into the house, plopped down the grocery bags and flew downstairs. You could hear the hissing in the battery box and the firecracker smell was even stronger. The ventilator fan was fighting a losing battle. I stepped to one side so as to not get sprayed by anything that was causing that hiss and lifted the lid up. The heat hit me like opening an oven. The batteries…. all eight…. the equivalent of 16 lead acid car batteries were geysers! I dropped the lid down and grabbed the manuals. Because the county never really understood how this system worked, they required us to have a bunch of blade switch shut offs. I needed to find the one that killed it completely. Because the system has charge controllers to the batteries, I assumed that if I flipped those off that that would stop power from going to the batteries. After all, the batteries weren’t spewing water vapor. It was hydrogen gas… Think Hindenberg.
My solar guru teaches electrical classes in prisons to inmates. While there he is locked in and can’t have a cell phone with him. I called him several times, texted, emailed and generally freaked out. Turning off the charge controllers hadn’t worked. Fortunately, the storm hadn’t arrived yet and I turned off the furnace, opened up the windows and doors, and turned on a big industrial fan in the basement to help get the gas out of the house. At a 4% concentration in the air…… BOOM!
Troy finally called and was a freaked as I was. He sent me back down there and told me which switches to flip to shut the whole thing down. It reached over 300 degrees in the box and it took hours for them to calm down.
The end result that was determined when he came out on Saturday to inspect the situation, was a full on cascade failure of the entire battery bank. We knew that these flooded lead acid batteries could fail and if one or two did, it could render the entire bank useless, but this was all of the batteries and they had essentially turned into a hydrochloric acid spewing heat machine. The battery monitor data showed that at night, because of some sort of short, the inverter would notice a power drop on the batteries and start jamming electricity into the battery bank (on one evening it showed as much as 120 amps). Then, after enough of this, the batteries failed and went into JAZ Farm Chernobyl melt down mode. I was in fear for my life and I was also scared to death that something unexpected would spark and blow up the house. Not an exaggeration. The basement was flooded with hydrogen gas.
There are several factors that could have contributed to this:
1. The original engineers could have programmed the inverter settings improperly and had the batteries charging up too hard and too fast. As batteries charge, the temperature can increase, and heat and batteries are a bad combination. We had noticed at one point that they were boiling off a lot of water and that is one reason for having the tech out for a check up. Things were corroding and it turns out that a vital sensor had completely crapped out.
2. Because of the rapid boil offs and the corrosion, I was told that perhaps I was adding water to them too frequently and it was venting off due to over-filling (this turned out to be nonsense). The Tech told me to not fill them monthly and go to a more 4-6 month schedule. However, having done that, there was still massive corrosion build up indicating that something was still a problem. Also, for a good deal of time over the past year and a half, I’d been unable to walk.
3. Lastly, and what seems to me most likely, is that because of the massive loss of water from not having filled them for 6 months, the lead panels inside the batteries had dried out sulphur crystals built up them (Sulphur is a normal by-product of the internal reactions; however, they would normally stay underwater). Once we refilled them, and the tech cleaned up the corrosion we had a powerful system up and running again. It is entirely likely that the sulphur came off and created a bridge between the lead plates; thus, shorting them out. A short, just like with wiring, draws a tremendous amount of energy and creates heat. This happened across the bank and the result, after a couple of days of this, was damned near a catastrophic explosion. The heat from the short caused the lead plates to warp and the system melted down.
Whew!!!!!!!!!! What a couple of days I’ve had.
So we are into troubleshooting mode. None of the batteries were salvageable but there are some possible warranty options so it might keep this disaster to a financially reasonable outlay. Did the electrical systems have compatibility issues with the batteries? Were the batteries defective? Was it the water issues? Are the inverter settings in error? We don’t know. However, within the week the new batteries should be here and then we can fire things up and start diagnostics. This. Should. NEVER. Happen. in a well equalized system. Needless to say though, Farmer Juan will never again listen to anyone who tells him not to fill them regularly. All is well, but currently we are sucking off the grid because we can’t run the panels without the batteries in place. As they say in the survival world, “Two is one and one is none.” The snow storm did arrive. It did not knock out the power thank goodness. But we did wheel the 200 pound 8000 watt generator out by the back door just in case. Redundancy is your friend.
On a happy note! While all this was happening, the barn grew a roof! We are waiting for one last set of sheet metal siding, and they expect it to be ready to be inspected on Friday. Goats and Donkeys will be here for the spring!
Cheers. My blood pressure is finally back down. This was terrifying.