Its been a good six years, on new store bought batteries, fourteen ( 6 volt)of them costing me 2100.00 dollars ( might have been 2300 I have to find the receit). I had designed things so I hoped to hit 10 years on my battery bank, actually it was designed for 8 but I found ways for greater load reduction that should have gotten me a couple more years. I didn't really expect 10, hoped for, but thought 9 should be doable and I would be real happy with that. I noticed greater water use this year, I record how much I use and this year it doubled. That's the first sign (or a sign). Now the 2nd sign has occurred twice this weekend. I get up in the AM and turn on the tap and I hear the dreaded low voltage alarm go off as the pressure pump kicks on. Puck, and going into winter as well! Can I just go out and buy new batteries...Yes, Will I?...no. Im going to see how far I (within reason) can ride this horse.
Why you might wonder am I getting less time out of my bank than I planned for.....well, there is a saying...most batteries don't die a natural death, they are murdered! despite my experience with batteries, I am guilty of batterycide. Once I inadvertently completely killed the entire bank (11.7 volts x2 mabey x3days)(when new) , and had to take aggressive action to revive the bank, and said action was harmfull in and of its self but I brought the bank back, then I had a misadventure with a wrench and confirmed that you can weld with just batteries.
I can also confirm batteries really like to have their plates covered in electrolyte. I have committed acts that only one of the examples given by themselves could prove fatal to a lead acid bank.
I estimated my actions could have knocked a couple years off the bank easy (the first nearly killed the bank then and there, and did knock 2/10ths of a volt capacity away then and there, non recoverable, despite the immediate cpr performed.
Im at 6.x years, I will try to milk another year and go to 7.x years before I replace these.
Now I get the chance to get creative and figure out a strategy to milk more life out of lead.
Give a man a gun, and he can rob a bank. Give a man a bank, and he can rob the world.
I just cant catch a break lately...burnt up terminal...
Give a man a gun, and he can rob a bank. Give a man a bank, and he can rob the world.
Yikes. This is a turnoff. You’re dealing with all those issues, but at least, you’re handy and can fix that kind of stuff. I’d be completely clueless...
So I decided to cull the pack and run with the best performing batteries....these ones didn't pass muster so they got pulled (should have pulled them sooner), this means I am down to a bank of 1125 amphrs, or 13.5 kw...leaner than I like going in to winter.It is what it is.
Now I will equalize the remaining ones hard if the sun co-operates.
Give a man a gun, and he can rob a bank. Give a man a bank, and he can rob the world.
A good day for sun so I equalized my remaining 10 batteries. took and held them to 15.44. I lot of bubbling going on! but this balanced out the cells nicely. Voltage readings are now looking good on all the cells. I added a greater than 100 000uf capacitance to the inverter input, this will now provide motor start up current rather than the batteries. I think I may make this a standard practice, adding a large cap bank to the inverter right from the start with new batteries. I am confident I can sail through the winter now with no problems.
Give a man a gun, and he can rob a bank. Give a man a bank, and he can rob the world.
Thought I would add that adding this large cap bank has made a hell of a difference. No sag on the buss voltage at all when a motor starts up now. If you do this make sure you do it right close to the back of the inverter, no cables longer than roughly 6 inches, and use large cables.I knew this would work but I am surprised at well it works! not a peep out of the low voltage alarm.
I should add this warning ...Electrolitic capacitors are polarity sensitive, if you don't know what that means do not attempt this, if hooked up wrong (backwards) this could turn each one of those fist sized capacitors into grenades...I am not kidding...thats the worst that could happen, and at the mild end of making this misstake they will start to smoke, heat up maybe burst into open flame generating toxic clouds. I speak from experience!!
Give a man a gun, and he can rob a bank. Give a man a bank, and he can rob the world.
People have asked me why I don't buy better, larger batteries. There is reasons for that. I have had better larger batteries, maybe the best... Back in 2008 I got a good deal on wonderful Excide batteries. 2 volt cells, 1100 amphrs each. I bought 24 of them. these where monster size batteries. they stood taller than my knee, had a clear case so I could see into the battery. The fist problem came quick. How do you move batteries this size, I don't know what the weight was but two strong men could not lift even one cell. each had to be moved using a engine hoist. Just try getting 24 of these into a basement.
Then being so tall they were at risk of tipping over due to a small base, and if one ever did there would be 5 gallons of battery acid (or more) everywhere. The size of the battery bank box I needed to build was going to be huge, and take up living space. The other problem I found was stratification of battery acid. For batteries that size (tall and narrow) you really need a large array of solar to keep the acid well mixed up when charging. I actually had to use a large welding machine to charge these proper (didn't have as much solar back then ). I quickly realized while these were great batteries they come with many handling problem. Then when replacement time would come I would have a huge task getting them out of the basement followed by a huge cost for new ones.
With these smaller/cheaper batteries I am now using, I can lift them myself,and still do so as I age, replacement cost is more affordable. replacements are stocked locally. I am still getting good value with these smaller batteries 2100 dollars divided by 6.5 years = 323 dollars per year. to be fair I should add 100 liters for fuel (about what I burn each winter for charging, it varies from as low as 80 to as much as 130) So 323+120 fuel= 443.00 per year in consumable costs to be grid free.
Give a man a gun, and he can rob a bank. Give a man a bank, and he can rob the world.
I figure I may as well save the battery acid. I don't have a use for it right now but its better to have it and not need it, than not have it and need it.
I have heard its good for removing rust from steel, and I have lots of rusty steel around the place.
Give a man a gun, and he can rob a bank. Give a man a bank, and he can rob the world.
For funzies I have been trying to figure out how much power that cap bank has added. It looks like capacitance power values are measured in joules, and as much as I keep studying this subject at google university, I just cant grasp my mind around how much it is, but in using one of the online calculators I managed to get a greater understanding of the relative power it is producing with respect to input voltage. https://www.allaboutcircuits.com/tools/capacitor-Charge-and-time-constant-calculator/
The takeaway I get is that while this has worked for me on my 12 volt system, its not a optimal way to use capacitance to solve my problem, this method would be better used on a 48 volt system, or even 24 volt. If you use the calculator you will see the power put out from storage into the capacitors increases by a cube for each doubling of voltage. So in thinking about this I had a epiphany...the best place to store charge is right at the H bridge, the 170vdc buss, I don't need huge fist sized capacitors. I can just add a bunch of smaller capacitors at the h bridge and because the voltage is so high I will be able to store much greater charge....well thats my theory....going to order myself a bunch of caps now and try it out!
Give a man a gun, and he can rob a bank. Give a man a bank, and he can rob the world.
thanks for sharing
you have given me a lot to think about
Yikes. This is a turnoff. You’re dealing with all those issues, but at least, you’re handy and can fix that kind of stuff. I’d be completely clueless...
I forgot to say, when you see something like this it indicates two problems. First a failure to catch this problem developing, cause a burnt up terminal like this doesnt happen overnight. Then if the other terminals are fine , they handle the same amount of current, then it indicates 95% of the time that the installer did not tighten down the screw terminal enough. (yes that would be me)
Nobody got the Joke....of course this did not happen over night, its a solar controller, it only works during day light.!! That was funny as hell.
Give a man a gun, and he can rob a bank. Give a man a bank, and he can rob the world.
Last year at this time I was complaining about how little sun we were getting in the fall, this year it is back to more typical fall weather for sunshine. Its Almost November and I am averaging 5 pounds of welding rod that I am burning up each day (6013). Roughly 90-100 amps per rod at about 24 volts DC so that's well over 2200 watts to burn up a rod. I have to stop by 4-4:30pm as the sun is too far west then but still that's pretty good...free power up till then. Life is good
Give a man a gun, and he can rob a bank. Give a man a bank, and he can rob the world.
Back to improving inverter performance with aging batts,
So it turns out I did not have to order in some caps to add to my H bridge. I had some in my tickle trunk from the things I take apart at the scrap yard. Its a huge one!
Its maybe coming up on a year and half that I have been using this model of inverter and have been happy as hell with it. I am only adding the the capacitance because I wish to aid its performance with weak batteries not because its performing bad.
So I got it open and was test fitting the capacitor in when what did I see? Smoke damage! I at first thought it was from the boost transformer as the flames scorched the side of it.
but no, it turns out I blew one of the rectifrier diodes, I had not even noticed a loss in performance from this inverter, and because of good build practices the damage did not propagate!
Not unexpected, I am certain the manufacture never thought anyone would weld with it as much as I have. Large air compressor motors and welding are the hardest things you can do to a inverter. In my case the welding is the hardest, not so much the burning the rod, its the strike up and getting the rod to start that's the thing that really pulls the amps. I have been told that when I am out by the garage and welding that I dim the lights in the house when I strike up. Doesn't surprise me. Anyway no big deal, just the weakest diode failed I wont fix it, but let it ride and continue using it as is for now.
I added the Cap and have been using it all afternoon, I will use it hard over the next few days and note how big of a difference this addition makes to its performance.
(so this inverter is now running with 9 of the 10 boost sections working, and working like a champ)
If anyone would like to have their inverters stress tested, just loan them to me!
Give a man a gun, and he can rob a bank. Give a man a bank, and he can rob the world.
I thought I would have to wait a few days before getting a idea of how well this worked but no, I can already say what a difference this has made. In the evening with no sun to help the batteries I did a load of laundry, I have a old 15 years or so old of a washer, when agitating the clothes the motor goes in one direction for a couple seconds then stops and goes the other direction, So lots of motor stopping and starting! normally with my weak batteries each time the motor changes direction the lights would flicker, not now, not even a hint of flicker.
So I got up at 6:30 today to check on things, observed the battery voltage at 11.9, then I activated the pressure pump to see if I could trip the low battery alarm, no chance, the pressure pump snapped right to attention. That's the heaviest motor load I have for the house.... this is working well...
this gives you a idea of how shot my batteries are, even when getting a full float charge the day before my batteries are dropping down to anywhere from 11.8 to 11.9 under normal use over night . The low voltage alarm sounds at 11 volts and the inverter shuts of at 10.5, before adding the first capacitor bank to the inverter it was becoming common for the fridge to kick on sometime in the night and take the battery below 10.5 on start up and shut the inverter off.
Give a man a gun, and he can rob a bank. Give a man a bank, and he can rob the world.
Can’t you refresh my memories on how long your batteries lasted vs expected life? I seem to remember you making your mea culpa over maintenance and so other “oopsies”. Going off grid solar is an eventual goal of mine, and I much prefer hearing from someone with real life experience than from the used car salesm... err... solar vendors.
