keeping the solar backup power alive - battery change out

mountainmoma's picture

I put in Solar electric when I bought this house 26 years ago, so I have a 26 year old solar system. In retrospect, I should have bought nickel iron batteries at that time ( if they were even available, I didnt hear about them back then) But, I didnt. So while my inverter runs great, it was time to get new batteries. My last set were damaged in the fire here 3 years ago, so while they were actually very long lived batteries, one of them, so one third of my storage, died in the power surges in the fire and since they dont make those any more, I wanted more backup power, you cannot combine different battery types in the same battery bank. The partially broken set at this time is only a bit over 4kWh of power, which is ok for some locations, but for this location, I could not keep the internet box, a few lights, and the refrigerator going for more than 2 days, which is not enough. Last January was the first time in my 26 years here that I had to throw away all my refrigerator food.

I ended up getting 3 new batteries as part of my post fire rehabilitation work on my place, finally, and money is still a thing and I am already 62 years old, so, I still do not have a set of nickel iron batteries, but I have a very nice set of lithium iron Phosphate (LiFePo) batteries made here in California that should, barring any natural disasters, be the last batteries I have to buy.

[Skip this paragraph if you dont care about different lithium batteries - First, not all lithium Ion batteries are the same, not at all. The realy common ones used in consumer products and most electric cars have cobalt in them and other chemical differences. Mining cobalt is realy bad, first, for the environment, and also for the peoples health who are "mining" it, with no worker protections. Those other realy common Lithium batteries have problems with thermal runaway conditions and starting realy bad fires. You can imagine that in the fire zone as I am, I dont want any batteries like that in my garage. I would go back to lead acid batteries before I installed a power wall. Realy. ( For other reason besides fire though that I wont get into right now. I know that Tesla and others are switching to some degree away from the lithium cobalts) So, the ones I have use common ores, are safer, but the production is very high tech, not something for a power down world, we need to go back to using very few batteries and for when needed, use nickel iron as high tech production goes away in the future. The other reason I got the brand I bought within the offerings of LiFePo I could find is that some are cheap imports, and I want mine to last. Mine are made in california. I did find a small company I liked, and I do trust their import suplier, but they were optimized for cold locations. My battereis will run in temperatures well over 100'F, and I do not need a built in heater for the winter. So, do your research if you decide to have some battery back up power for our "transition time" . A last reason why I would bother with batteries at this time, is that I already have alot of sunk costs, a system that already exists, so all I needed were batteries. ]

This is my first time changing out the wires in the DC disconnect box myself and not hiring and electrician. The batteries are different enough that they use different wire diameter, and the new ones have built in circuit breakers and didnt need the old fuses. I realy, realy took my time with this. I turned off the entire solar system, thru the bypass breaker fro the house circuits, and left it off for 3 weeks while I slowly unconnected and reconnected. I triple checked that this was so, I confirmed with a voltmeter in a few locations, after waiting a few days after turning it off in case of any stray charge kept by a capacitor or something before I even checked with the voltmeter. But, once it was confirmed completely off, I slowly proceeded.

Here is my system with the old batteries. That photo shows the cover off the disconnect box with all the 48V DC connections for the system.

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mountainmoma's picture

I have stripped away the old connections at this point, the only reason I considered hiring an electrician, and why I did so before, was getting a wire into this relatively tight location. I needed another realy fat wire, like the fat black one in the photo, to come up, make a u turn, and turn down to fit onto the hole next to that fat one. Once I figured out how to finagle it in, I knew I didnt need to call anyone.

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mountainmoma's picture

The new batteries are Simpli Phi 3.8 and they have a metal case. My garage usually doesn t flood, but it has happened. Here is the beginning of my platform building.

I am using left over wood from the barn building, I cut 2 2x8 scraps to length on my chop saw. I had leftover treated wood too, which I dont like, but the guy I hired used it against the foundation, so I figured I should use the scraps for ground contact here. I cut thre and laid them flat side against the other and screwed them down. Then, I took 2 more pieces of treated 2x4 and laid them crossways to these and screwed them down. Then I turned it right side up, and I had a few of those rubber padding pieces that fit together like puzzle pieces, so I cut that to fit the top and hammed down in just a few spots with poultry netting staples so it would stay in place.

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mountainmoma's picture

I put the stand in place and then waited for my son to come over on one of his days off to put the batteries on it, as they are 86 pounds each.

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mountainmoma's picture

I put in stress relief for the cables in the DC disconnect box, which it did nto have before, which filling those holes better will also keep out rodents.

The bus bars have a spec for tightening, which is hilarious as the engineers say 13.3 ft pounds --- I did use a torque wrench, but I dont have that kind of precision. Certainly they are less than 14 in any case.

I am glad I saved those realy fat wires from back when I had lead acid battery bank, because, see , here I am having to use them again. I dont want to cut them off as who knows that someone may need them at a later date with a different battery bank ( not me)

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mountainmoma's picture

change the settings, and turn on the inverter to charge them up from mains power well ahead of any power outage, and done, here they are floating at their charged up voltage

I have the inverter set to not discharge below 80% drained( simpli phi tells you what voltage is the 80% mark), so I will now have 9kWh of back up power. This is for refrigerator, any lights I turn on, and anything I plug in like the internet modem box. I can choose to be very conservative as to what I plug in and for how long, I can cook and heat water on the wood stove for cloudy days, or the solar oven for sunny as the stove/water heating is not backed up, and the well and pressure pumps for water are no longer connected to the backup either, so it is also gravity fed water for the duration.

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Sweet Tatorman's picture

I think it a tribute to your knowledge and diligence to have kept your original lead-acid battery bank going for 23 years up until damaged by outside events. My sense is that most folks who get warm and fuzzy feelings about the idea of solar power likely cannot be trusted with a bank of flooded lead-acid batteries.
You clearly are a person that believes in paying dearly upfront to get long term reliability. I am impressed that your trace inverter/charger is still serving after 26 years.
LiFePO4 certainly appears to be the way of the future. I hope that their calendar/cycle life is as purported. Just in the past year I did the electrical for an off-grid tiny house and used LiFePO4 for the first time. There is certainly a lot to like about them vs lead-acid. While you clearly opted for the high end product, prices of LiFePO4 certainly have dropped hugely in the past couple of years so your timing of your battery update was fortuitous. My own bank of 12 Trogan L16s at 11+ y/o is long in the tooth and will before long be upgraded to LiFePO4 albeit of lessor capacity.
Given the age of your installation it was fortuitous that all of your existing equipment was compatible with LiFePO4. The fact that the battery as seen by the solar charge controller effectively disappears when in an overvoltage or under temperature charge inhibit condition can be a problem for some controllers that either need the presence of some voltage on their output to start up or the charge acceptance capacity of a battery to limit overvoltage due to the slowness of response of the controller to output voltage changes.
I cannot make out the brand from the photo but that solar charge controller looks somewhat like an older Midnite Solar but that company was not around 26 years ago (founded 2005). What brand is it?

mountainmoma's picture

The original charge controller is still there, it is a Trace charge controller, it is the small white box with the black heat dispursing fins on top. My inverter has 2 inputs for solar panels, and will take 2kW of panels into each input. I dont have much roof space, so when I first installed I put 24 Astropower brand 12V, 120watt panels ( connected in groups of 4, obviously to get 48V) on the roof. Those are all still there, although giving out less power, and still go into that old Trace C40 PWM charge controller. About 15 years ago when I had the house reroofed, I had to take all panels off and put back on, At that point I added 3 panels and a charge controller onto the other inverter input ( Evergreen 210's, so about 500Watts (derated) total, 1/4 of the capacity of the inverter input). The thought was that this would make up somewhat for the lessening of power output on the other string and make up for peoples increasing electronics power usage indoors. Anyways, those 3 solar panels are the only ones going into the Outback MPPT charge controller. And right now, that is disconnected as last years storms ripped off a cable up on the roof, and it is not connected back yet ( just try and get a guy to go out on my metal roof for a small job)

So, my old charge controller is a dumb one. It doesnt need to "see" anything to let that voltage thru. If the sun is up, it presents a voltage and a potential energy at its output. I realy love that feature as when the fire happened that feature made my set up so much more robust than my neighbors. After the fire, there were no power poles or mains power for a while. My old batteries stopped working due to the power surges. The inverter and the newer Outback controller want to see power before they will work, ideally battery power would do that, unless your batteries are drained of course. Which they are if they have been trying to provide backup power for weeks on end with no sun due to thick wildfire smoke. But, my system, the C40 charge controller presents that 48V potential once the sun hits the panels. The inverter electronics and display then wake up, but the inverter and charging function is off, for safety of course. Then, you just have to walk in there and scroll the menu and hit inverter on and it all works, until the sun goes down. Get up and do it every morning and have power during the day. But, even if that were not the case, the inverter would charge set the batteries right just with mains power when it was up and then the new type charge controllers would work, correct ? I am not sure if I understand what you mean by a potential problem, do you mean if mains power is out and the batteries shut off to protect themselves as they have been discharged alot during a long storm and no sun and then the sun comes out, like we had after the long time of fire smoke ?

The new batteries, Simpli Phi 3.8 are meant as a lead acid battery substitute. My inverter was a very good one in its day. It was made in california, and hte original Trace Inverters are known for this, there are still in service all over. A neighbor 5 miles from here has an old Trace 24Volt system still running and is connected to an old Sunfrost DC refrigerator in their garage, also still running well. So, my inverter has enough setting flexibility to give these batteries the settings they want, for example, my inverter will let me set the low battery cut off voltage of 50.3V that the Simpli Phis want, where as less flexible inverters wont go that high for that setting.

The batteries that were damaged in the fire were not lead acid batteries, that is why the big fat cables were not connected. The Aqion batteries used individual thin parrallel wires to the inverter, you can see those in the phto, and their foot print each battery is 1ft by 1ft and then 3 ft tall, those old black batteries are not on a stand. But, luckily I saved those cables. A number of years ago, when my bank of 4 Trojan L16s were on their last legs, likely due to my misuse, I researched and bought what I thought should have been my "forever" batteries. I had bought Aquion batteries, 3 of them. Those are sodium Ion batteries, with carbon and maganese if I recall anyways 2 very common ores for cathode/anode. So, the Aquions should have been protected by the fuses I had in the DC disconnect box, but one of the fuses didnt blow quickly enough, and the thing about Aquion batteries is that they do not want to give very many amps at once.

It must be nice to have such a large battery bank as you have. I bet you even take care of them better than I was able to back when I had that kind !

I am just putting this into service, so we will see, I hope it all works ! Some of this is confusing to me, because, yes, I kind of do wonder sometimes how having 4 sources of potential DC voltage all connected together dont fight with each other, and somehow power ends up into the inverter. I know it works, but luckily I dont need to know how it works. It realy has been a hands off power source overall.

My battery journey : Came with 4 sealed 12V batteries, " training wheel batteries" that could never last long, but didnt need watering; Then after a short time, the real L16 batteries; then the Aquion sodium Ion ( "salt water") batteries; and now the simpliphis.

You seem to know more about solar than I do, I would love to aks you a few questions, as I put those 2 working aquions in the newly rebuilt barn, which had burned down in the fire, and at present is not connected back to any power. I should be able to have a couple panels and a minimal charge controller to charge those. But for a DC only system, isnt there some component that is a "battery saver" so that I can connect DC loads to those batteries and not over drain without having a inveterer ? I know I can easily by a 48V DC to 12V DC conversion thing to run DC lights, but I do need to protect those battereis

Here is a phot of the panels n the roof, there was a lot of deferred maintanence after the fire, all that overgrowth has just been cut by the house, and I am attempting to get the garden back.

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Sweet Tatorman's picture

Ha! My brain failed to even see your Trace C40 in your photo and focused only on the Outback MPPT next to it.
There are things about your description that are confusing to me. Nothing you have said suggests that this was a grid-tie setup yet you say " My inverter has 2 inputs for solar panels, and will take 2kW of panels into each input" which only makes sense if it were grid-tie. Perhaps you mean that the distribution blocks that combine the outputs of your two solar charger controllers and the battery connection are located inside the Trace inverter/AC mains charger unit??
When operating in the daytime only post fire, you do not explicitly say that no battery was connected. I can see this working even with a very compromised battery connected, say only a fraction of 1% capacity, but would be surprised if it worked for you if the battery was totally disconnected. In theory it could work as the input capacitors of the inverter were serving as the "battery" and the applied load was less that the available power from the panels. In practice it would be problematic as a passing cloud or the surge required for refrigerator compressor startup would trip the inverter on low voltage.
Partially answering some of your questions, I looked at the specification sheet for your batteries and saw no mention of low temperature charge inhibit function so no charge controller issues arising from that function to worry about in your case. The SimpliPhi spec sheet is mum on the BMS setpoints for under and over voltage but since you are setting you inverter UV setting at less than 100% DOD you should be good on the UV end and if your charge controllers can provide the appropriate settings then you should not cause the battery to ever go into an OV charge inhibit condition.
BTW, I know nothing about the salt water Na-ion battery chemistry and had no memory of having heard of Aquion. I did Google Aquion out of curiosity. A bit of a sad story there. They managed to burn through ~$200 million of subsidies and investor money while only managing to ship any product for a couple of years prior to bankruptcy.
You question here: "as I put those 2 working aquions in the newly rebuilt barn, which had burned down in the fire, and at present is not connected back to any power. I should be able to have a couple panels and a minimal charge controller to charge those. But for a DC only system, isnt there some component that is a "battery saver" so that I can connect DC loads to those batteries and not over drain without having a inveterer ? I know I can easily by a 48V DC to 12V DC conversion thing to run DC lights, but I do need to protect those battereis".
It sounds like you are saying that your remaining Aquions can be configured as a 48V battery. Many PMW charge controllers, your Trace C40 included, have a load output for DC loads. This load output shuts off on low battery voltage. Often this UV shutoff level is not adjustable so may or may not be compatible with requirements of your Aquions. There may be PWM controllers where the load UV cutoff value is configurable, but you will have to do your own research to find as I don't have a recommendation off the top of my head.

mountainmoma's picture

My set up is grid tied. It doesnt have to be, but it is. Now I am confused too, as I thought it was explained to me that there had to be 2 separate banks of panels to get the full 4kW potential, I will go look. Ok, no wonder you were confused. There is only one DC input to the inverter, and everything connects together in the DC disconnect box. It was explained to me when I bought it 26 years ago that I had to have 2 separate 2kW strings if I wanted the full 4kW, which I didnt have room for with panel sizes at that time. This was such a pug and play, except for batteries, for me over the years that I realy never paid attention to the details as I didnt have to. I am now wondering if the whole 2 separate strings of panels thing was because of the charge controller limitations of the time.

When the fire happened, the power poles burnt down and melted and shorted wires, 2 locations to my backed up circuits( external office, well pump) also burned to the ground and melted those wires, so shorted them together, to the inverter backed up panel. This caused the inverter for a brief time to try and supply power ramping quickly to max power output. The inverter tried to get power from the batteries to supply that and so that blew the fuses to the batteries, one of the fuses delayed enough that the battery it was protecting was damaged. In any case, all fuses were blown to the batteries, Mains power was gone as the power poles burnt down, there was no power there. For a couple months. I could turn on the inverter in the morning due to the power from the panels thru the C40 charge controller. You are right that if it got cloudy enough, the inverter would shut down again like it was night. It never got that cloudy during that time, if it had, oh well, it would have shut down and I would need to have turned it on again..... it is not spec'd to work without batteries, it should have batteries, it just didnt at that time due to the fire and it was nice to be able to use it in a reduced capacity. Eventually, after a month, I remembered that there might be fuses and found them and bought new fuses for the batteries.

Yes, after I wrote last night, I went and looked up further, spent more time about the battery saver issue and yes also found out the C40 can be used that way too, which is nice as those are not very expensive, and undervoltage adjustable. Yes, the 2 Aquion batteries still work, so they are a battery bank. So, I am toying with the idea of having them in a small system provide lights for the barn and in the future refrigerator backup for the studio apartment I rent out. I am still running the cost numbers on that, so am looking up needed components, small refrigerators. There is a limited time to decide something as the Aquions will lose charge eventually sitting there unhooked up in the barn, it would take months at least, although it likely wouldnt hurt them much if they did. Good chance it will be too expensive -- but running new conduit and wire that far for AC power to the barn is very expensive too.

A chinese company bought out the patent/design for the Aquions, and a European company was producing under license I guess had them too for a while, I think you can get them in Australia maybe parts of Europe. The importing company, from the European manufacturer, here shut down during COVID, so dont know if that was just here or Europe to.

Alot of Aquion batteries were sold to the off grid market in Northern California, they were popular, it was shocking when they folded, but Power walls got most of the subsidies and publicity. Alot of grid tied homes are AC coupled and need some kind of battery charging/battery management and this was a definite strength of the power wall as it was all in one. Of course, the Power walls have a ton of downsides. Including lithium and cobalt, and having to connect to the internet