Greetings my patient readers! Sorry for the long break, but you didn’t miss much. Both Buttercup and I decided to quit our day jobs. The Pandemic gave us an offer we couldn’t refuse. So far 5 months in we haven’t missed work much. If anything we are doing more physically than we ever did at our jobs. And every day we find more stuff to do, so boredom is definitely not setting in. A big bonus to me is sleep. My job required me to reset my circadian clock once a week for at least a 6 hour difference. So sleeping better and more buff than in 20 years, what more can you ask? We left off in the Summer of 2019 with the post bases for the deck finally done. We then came out for a month or so in the Winter of 2019 and did the initial setup for our off grid power system. My initial thought was “Hey, I’ll let someone else do the work for once and just buy a Tesla Powerwall”. This is the Tesla battery system that was designed mostly for people in California to buy power from their failing and expensive utility companies at night when it is cheapest and use it during the day when the rates are higher. It holds 13 Kilowatt Hours of power, which considering that we won’t have an air conditioner and will only be running lights, refrigeration, and electronics should last us about 4 days with no recharge. I enthusiastically called Pro Solar, the local company that has the exclusive Caribbean franchise for the Tesla Powerwall. Only $7K! (about $1000 over Texas prices). “Sweet, send me an installed quote” I naively said. Once the quote arrived I realized that Jimmy Buffet was right about Landsharks in the Caribbean! $4k for installation (bolt it to the wall, connect 3 wires…), plus another $3k inspection and regulatory fee (would they even know what they’re looking at…) for a total cost of $14K or 110% over Texas prices.
Not too happy with that development I turned to our good friends and neighbors Amber and Matthias, who were in the process of building their own off grid system. We jumped in with them on a Chinese lithium battery buy. The total cost was about $5k for 14 Kilowatt Hours of power, although some assembly was required.
The beauty of this specific box is that it combines the solar controller/battery charger with an AC inverter to convert the battery power to house current. It also has a mode which enables you to set up the circuit breaker boxes just as you would in a regular house and to get both 110 volt and 220 volt power. Using US or European equivalents to do this would have involved having 3 or 4 boxes talking together and about $4K in equipment. This one arrived on the Island for less than $1000.
The worst part about buying batteries directly from China is the 3 months wait for the slow boat to arrive. Fortunately ours made it on the boat just before China shut down for the Pandemic. And we’ve all heard about how dangerous Lithium batteries are, do you really want them in your house? Thanks to progress, there are new formulations of Lithium batteries that are very safe. These are LifePo4 (Lithium Iron Phosphate). Compared to the pure Lithium batteries used in cars and cell phones, these are very safe. They don’t burn or explode, but they are heavier than pure Lithium per unit of power. It doesn’t really matter much as together these 16 cells weigh about 140 lbs. To give you an idea the equivalent weight of normal lead acid batteries would be about 800 lbs! Not that I trust the Chinese though…
Since these were resting in the basement of the house I decided to build a concrete board lined box to put them in, just to be sure. The red box that is fastened to the outside is the BMS (Battery Management System). This is how you keep your babies from getting too hot, too discharged, or too overcharged. It monitors each of the 16 cells and will kill either charging or discharging power if things go amiss. This particular one didn’t work very well initially, so I went all in and got the latest BMS from China. The equivalent Western version is about $500, the Chinese one was $125 on Ebay, but then we were again waiting for the boat. Once it arrived, I discovered some assembly was required…Again!
This BMS is rated at 250 Amps. Our 16 cell battery system runs at a little over 50 volts DC, which means with our 5000 watt AC inverter the most current we should pull is 100 Amps. Awesome! But wait, look at the 2 blue wires. These are where all that 100 Amps is supposed to run through. If you put them both together and measure them you end up with the equivalent of a US #5 wire (there is no such thing, you can either get a #4 or #6, but if we made one this would be it). A US #4 wire is rated for a max of 70 Amps, so this thing might be good for 50-60 Amps. The only thing I could think was that the Chinese have different physics laws than we do, or that like most things Asian it comes from the “Land of not quite right”. The next task was to locate the instructions on how to put it together. Ever watch a You Tube video in Chinese? I did! It didn’t help much, then I finally found a series of pictures with English subtitles that helped me assemble it.
It was a little nerve wracking on initial power up, there were a lot of parts of the installation pictures that said if you hooked it up wrong the “board will burn!”. But the miracle occurred and it worked! Next was to get the app on my phone since the board is Blue Tooth. Once again the Asian gremlins attacked and the app was a POS. Great thing was that a guy in England had previously gotten pissed off at the Chinese app and made a new version that works very well. It really is a good system now that it works, lots of cool features (individual cell voltage, transistor temperature, battery temperature, battery balancing). The only really concerning thing is those undersized blue wires. But wait, I just ordered the newest version that is rated for 450 Amps, and this one has 4 of those blue wires instead of 2. So it might actually handle 100 Amps without breaking any physical laws! The bad thing is I’m waiting on the slow boat again!
The other great thing that happened is that we got a line on a bunch of surplus 275 watt solar panels. These were from Hurricane replacement jobs, which meant they had some small scratches/damage. The best part were that they were the older style that hooks directly into the solar controller versus the new style that has built in microinverters. This is exactly what we needed to use with our Chinese controller/inverter box. We bought all they had, about 25 for $100 each. After testing we only found one bad one, so things are looking up!
We did a couple of little projects as well on this trip. One of the joys of living on an extinct volcano is making your own dirt. Yes, there’s either boulders, fist sized rocks, or pebble sized rocks in any given sample you dig up in the yard. A fun thing to do is to station various Homer Buckets all over the yard. Then you make a vow that every time you walk somewhere in the yard you will deposit at least one rock in a bucket. Totally works, though we haven’t gotten to the implementing stage of that project yet. In the meantime we made a dirt sifter that in the end makes almost no rock dirt:
The production ratio of input to output is not great. But it does at least get the big rocks in one place. Also missing is any organic matter in the newly sifted dirt. So we started a compost pile to remedy that. Maybe in 10 years or so we’ll have enough nice soil to make a flowerbed or two! Another small problem is how to keep the climbing frogs out of the cistern. Once they take up residence in the cistern it is very hard to get them to move on. I made a couple of Lexan covers to go over the cistern vents. They let the overflow water out as well as preventing unwanted house guests.
At this point we’re up to Day 170 of construction time. It was August 2020 and I was starting to get nervous about being on the Island during the latter part of Hurricane Season. Just as we were leaving we got the good news that I had received an early retirement. They didn’t have to tell me twice!!!