November 18, 2015
We purchased our last set of batteries, Trojan L16H-AC, for the solar system about four years ago. We had eight six volt batteries for a 48 volt system. Under optimal use, the batteries should have lasted at least five years, but the life span diminishes if the batteries are discharged too much, too often. A couple of weeks ago, we noticed the battery bank was not holding its charge very well. Testing the cells with a hydrometer, we discovered that several cells were dead and EQ’ing them did not help revive them. Time for new batteries.
This week we replaced the bank with a set of Surette L16-S550 batteries. Still eight six volt batteries but the Surettes are supposed to be a superior battery. Perhaps we can treat these more kindly than the last set and get at least five years out of them.
It took us about an hour to hook up the new battery bank and so far it is performing real well.
What was disappointing is that battery technology has not changed in the last four years. Our choices were the same as four years ago, and the price didn’t change much either. We had followed the introduction of the new Tesla Powerwall batteries this spring and hoped we would see better technology when we bought our next set of batteries. The Tesla system still interests us but it would require a wholesale change of our entire system – batteries and inverter, and there still isn’t enough info out there on how it will work in an off grid system. Perhaps in five years time, when we are ready for a new set of batteries, it will be a viable option.
In the meantime, the winter solstice is approaching. One more month until the shortest day of the year. So far we are fairing well, but using the generator more than usual. Mostly, we adjust our power usage to match the power we have. If there is not enough sun to charge the batteries up during the day, there is no TV watching, no making smoothies in the blender, no power tools, etc. However, in the two months before and after the winter solstice, we need to fire up the generator when we have several no sun days. With the old batteries not holding their charge this year, we needed the generator for essentials – fridge, freezer, lights and Jets games. Noisy, but it does the job. Now that the new battery bank is in, I am hoping to hear a lot less of the generator.
It may seem backward to some to have to forgo activities to conserve power. But the nice thing is so much of what we do, does not require electricity. Today, our first winter storm of the year hit. The snow and high winds are making for very blustery conditions. There was not much sunlight today, so tonight we will hunker down for a quiet evening. But the wood cook stove is fired up, so cooking, heat and hot water are taking care of. The batteries are sufficiently charged for lights (and the laptop) and the water pump. Our fridge is in a cold room so it doesn’t need to run much, and the freezer is in the unheated porch so no worries there. However, our neighbors are not fairing so well. The power is out and with it, their heat, lights, stove, TV and more. Luckily it is not yet really cold out (only -5C) but even so, if its not back on soon we could have a few visitors.