*Aging or Ageing? Both seem to ‘fly’. Dictionary gives them both equal time….?
We have 12 batteries in 3 separate groups. They are all of the same size and age and each group makes up a 200/210 amp hour ‘pack’. So the three packs give me 600 ah. Maybe 630. My alternative energy friend, Mike made some discrete queries regarding the state of my system and then politely suggested that he come by and help me rotate them.
“Rotate them?”
“Yeah. Rotating ’em stretches their working life. It’s a good thing to do.”
“Splain that, dawg. What does the rotation look like?”
“Well, imagine these four batteries lined up in a square. They are then marked numerically say 1, 2, 3 and four and so are the spots they are in. Clockwise. We will rotate their positions beginning with number one down here at 7 or 8 o’clock and going around til we get to the one here (pointing) and that’s number four. We mark ’em and then take the bank apart and make sure that all the batteries are put back into the same group but in different places. In this case, they will be 3, 4, 1 then two. Repeat for the other two banks.”
“Well, I am in to this shuffle if you say so but what is the logic? Seems we are just moving batteries around. Given that they all make up a 48 volt pack battery, what difference can moving them around make?”
“No Idea. But it works. Batteries are weird, man. It’s like the juice comes in and the juice goes out but the middle batteries do not get their share or something. So, ya gotta mix ’em up to get the most out of all the batteries. Don’t ask me, man. All I know is that it works.”
So, we did it. We mixed them up. We took them all apart one group at a time and cleaned every terminal and did other minor ‘battery fuss’ and then rotated them. Then we put ’em back. Took the afternoon to do it. Half my batteries are up at waist level (brilliant) and half of them are under that level on the floor (stupid). Getting at huge black batteries on the floor in the back of the closet is awkward and heavy going. Each battery weighs 160 pounds. But, working together, it was easy.
“I think these are 250 amp hour batteries, Dave. With three sets, you have 750 amp hours of batteries, dawg! That’s some serious juice, man!”
“I am pretty sure they were sold to me as 210 maybe 220 amp hour batteries. I rounded down in my head – to 200. So, I have been figuring 600 and I thought that a smidge light. But if they are 250’s then that’s 750 amp hours and that would be great. Mind you, they are all five years old so they are on their latter days.”
“Gonna cost you more than $6,000 to replace these. More if you go with Surrette or Discovery. But they may see you out.”
“I know. That’s how I plan these days. Can I get something now to ‘see me out’? Grim, eh? I used to only look at inch thick stainless steel fittings to see me out but now I am asking for the warranty on clear plastic roofing. It’s all relative. Another decade and it’s green bananas and hard avocados. Mind you, working with a gazillion amps of batteries like this and I could easily be seen out prematurely so it’s all moot, really.”
Our Off the Grid Home 
Well.
I WAS going to comment on your ageing “batteries” but I was late for work so I had to haul ass.
I’ve heard about “rotating” batteries before….apparently NASA does it on the International Space Station ( weightless batteries are Sooooooooo much easier to “rotate”) but I had no idea what they meant so I filed it away in my tiny brain for future reference…
And, thanks to you.
Now I know.
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I hope that bit of info didn’t displace more important stuff jammed into that small space. Only hold so much data on a 16 bit chip, ya know?
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More like an 8 track that stops halfway through life’s “song” to rewind……
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I haven’t heard about the rotation before. As I mentioned before we just bought new Interstate 6-volt deep cycle batteries to replace our old ones. We have two separate battery banks that we switch between, one set for day and one for night. Plus, if something goes wrong, we always have a backup. Each set now has eight 6-volt batteries wired in parallel to make a twelve volt system. They are rated at 232 AH, so each separate system theoretically has 928 AH if I have done the math correctly. I’m no expert in electricity for sure. In the winter, they don’t last us very long, but we have few electrical needs – a few lights, recharging our devices, a “TV” for watching videos (essential during those long dark nights), that’s about it. Our compost toilet has it’s own panel and battery and so does my garden hose. Our friend John did the installation and Wayne keeps our systems running. All I have to do is use up the juice. – Margy
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‘Using up the juice’ is the easy part. Even making the juice is relatively easy (expensive but easy). It is STORING the damn juice that is the biggest challenge. And my ‘energy’ guy is BIG on battery rotation as a means to ‘stretching’ the life of batteries. He also claims that they perform better in the meantime. I am in year five. If I can get two or three more years out of them, then my next REALLY heavy duty and expensive set will see me out.
We’ll see.
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My apologies for not commenting. I have been thinking about your post though. The rotation does make sense. If your batteries are not perfectly matched (internal resistance, voltage, etc) then one battery will do more work than the other. I connections between batteries increasing the minute imbalances between batteries, as no two cables would be perfectly identical (yes, redundant grammar). Thus, depending upon where a battery is in the wiring scheme could impact its ability to be the ‘strong’ battery that does the work and rotating moves batteries in and out of the ‘strong’ position. And, the more work a battery does reduces its life span. So, balancing position should balance the workload and then extend life.
I think. If I remember my uni classes from way back when. Same problem with multiple pumps and fans in systems.
Second point, we’re getting ready to start building out our power system. You mention that you use 8D batteries. Do you pick these up from CTC or?
Oh, I don’t comment often, but I do read every post. Always entertaining, or enlightening or educational, or a diversion. 🙂
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Hopefully just an entertaining diversion. DO NOT TAKE ANY ADVICE I GIVE. I just know what I have learned so far and that process is still going on. Having said that, I went with 8D’s because a friend was in the business and had a ‘deal’ on them. Local Wisdom is that L16’s are slightly better. The REAL way to go is Surrette or maybe Pacific (new) they have thicker plates and will recycle twice as often but, of course, they are more money. I believe that everyone screws up their first batch. Mostly because everyone I know has. Including me. So, to my way of thinking, get the best bang for the buck the first time, hope you get almost five years and learn how they ‘live’ with you. Monitor them every three months bare minimum. Then, if there hasn’t been a much needed breakthrough in some new battery product (I.e. MUSK) in that five years, go to Surrettes or better. And you are right – do not skimp on the connections. They are the weak spot of a generally weak component in your system.
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