Six years ago when I was building The BV I had two options for batteries. The best option at the time was previously owned, telecommunication station (cell tower), lithium batteries. The cell phone companies were at that time, and for all I know maybe still, replacing batteries every year. They turned around and sold them in the used market for $1000 each.
It has been a while since I have written a post like this. An actual technical article. We are going to talk about volts and amps and all sorts of fun things. Some of my long time listeners will hark back to my early posts where I was stringing wire. The rest of you, hang on.
These cell tower lithium batteries were really perfect for some deeper technical reasons as well. But it didn’t really matter. For my van I needed at least three but maybe four of them. Quite simply, my project did not have a four thousand dollar battery budget. Back then I lived with a person who got angry any time money was spent. I had a limit of what I could ease out of a couple paychecks unnoticed.
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| Two hundred sixty two pounds of batteries! |
With option one out, I went with the other, not-the-best option. Lead acid. From the outside they look just like the one you have to start your gasoline car. (Quick side note: I just realized for the first time in writing I had to explain the car type. Not many years ago I could have just said car. Everyone would have pictured essentially the same thing. Isn’t that cool?)
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| I really wish I would have taken a picture of the new batteries next to the old ones for scale. |
Lead-acid batteries are bulky. They put out sulfuric acid fumes. Sometimes laying in bed, if the furnace was running, air was being drawn into the van. I could smell them. I could lay there at three in the morning and think, “this can’t be good for me.”
The specific type of lead-acid I need are called “Deep Cycle” batteries. They are really best known because they use(d?) them in golf carts. I guess the difference is the lead plates are much thicker and that is why they are heavier. They are almost twice the weight of a car battery. Just over 66 pounds each, so two hundred sixty two pounds I have been lugging around.
Looking back at how I was using the van at that time, maybe they were even the better choice. One winter the temperature was -27F (-32C) outside. I need to do some research on this in the next week or two, but I think there is an issue with charging lithium batteries when they are below freezing. I will get back to you on that. That year it was so cold even the lead acid batteries were frozen and a little swollen. I know that was hard on them. I suspect I am going to need to heat the battery compartment. At least now it will be less area I have to heat.
My initial design, since I lived in the frozen northland, was to have enough battery power to last ten days. It was very common to have seven days of solid overcast. No solar to speak of. I needed to be able to run the propane furnace and the lights. I developed a routine where I would heat leftovers in the microwave but after three cloudy days I would switch to cold food.
The first year I had a lot of struggles because I have only a high school graduate’s understanding of physics and how electrons move. I was always low on power and I couldn’t mathematically figure out why. In the end, after more research and learning I discovered what I had done was wired the battery bank incorrectly. I had wired it from one end (saving wire!) rather than across it (fills the whole bank with electrons) In the second year I used the shop belonging to a friend of number one son to rewire it. Wow, huge difference.
Each battery holds 250Ah (Amp Hours) of electricity at 6 volts. The way I have them wired (series/parallel for the wiring nerds) I get 500Ah of electricity at twelve volts. But here is the catch. If you ever drain the battery below fifty percent, it causes damage. Many people don’t know the same thing is true about your car battery. Leave your lights on while you are in the pub and kill your battery. Once or twice that’s no problem. Get a jump start after the beer you ordered when you went back into the bar to ask your buddies for a jump. Down the road you go. But if you do it very often your battery gets ruined.
The lifespan on a lead acid battery is typically five years. I have gotten six. I babied them. I never let them get below 50% charge. In six years I think the lowest I ever went was 53%. I got a good life out of them but now they have to go. I was getting great solar while I was in California and everything was just fine. One cloudy/rainy day with me working in the van, running the Starlink dish, charging my laptop and heating lunch in the microwave, my batteries were in the low 60%s. So they have lost most of their capacity to hold a charge.
The new ones I am installing are called Lithium Iron Phosphate or LiFeP04. I Still need four of them but they are much smaller. Much lighter at about 12lbs each. Still not cheap, but they are $160/each, brand new. A lot cheaper than they were. Unfortunately the solar charge controller I owned was not easily compatible with the new batteries so it has to be changed out as well.
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| The new solar charge controller. |
When I bought the first one it was an expensive bit of hardware, somewhere in the $600 range. The new one is smaller, lighter, more efficient. I paid $120 for it. I will also have to buy some type of shore power battery charger but I am confused about compatibility, I will kick that buying decision down the road a bit. After all, these days I very seldom get a chance to plug in anyway.
Taking out the old solar charge controller and all the extra wire was another 40lbs of weight savings. All told I dropped at least 250 lbs out of the very back of the van, behind the rear tires. I have to believe I am going to feel the difference.
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| A problem with getting new stuff! It doesn't fit the spot the old part took up. I will have to do a little wood fill-in. |
One new bit I am adding to the mix, I am going to add a secondary inverter. This one is going to be only 300 watts and a pure sine wave inverter. It’s only job will be to run the Starlink dish and charge my laptops. Right now I am running a 2000 watt inverter, maybe a ten year old design. I know it isn’t very efficient. I will keep it in place to run the household electronics. The microwave, coffeemaker, toaster and rice maker. …Oh, and don’t forget those cute little Texas shaped waffles. Most of the time it can be off and not using any power at all.
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