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Forum Index : Solar : My first LFP battery install
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yahoo2 Guru  Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
Next time I will have all my test gear with me and i will manually push it into shunt voltages and see what happens. they were all within 2mV at 3.55volts but some rain that come out of nowhere and me a bit limited on time meant I couldn't stuff around for too long. I figured that was above the full capacity mark so it would have to be good enough for now. I have been trying to encourage them to use a heap more power to give the battery bank a decent workout but old habits die hard, they may have to rent a teenager for a month or two, that should fix it! These have a 2A shunt, the highest I had a couple of them while I was testing it was 650mA. they didn't seem to max out when the voltage limit for the charger is set at 3.65V per cell. I have no doubt they would if a cell was at a much higher voltage than the others. I have to say Klaus, I am pretty impressed with the LFP's so far, makes me want a set for myself! I'm confused, no wait... maybe I'm not... |
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Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Oh, I thought you already had a set  . I still have only a 200Ah @24V bank and wish I could double that. Might have to inquire if the price for these LYP cells had changed for the better during the 2 years I had mine.
I am just increasing the solar input to 2KW, up from 1.2KW to get more charge on cloudy Winter days so doubling the battery bank capacity should go well. Yes, they do an impressive job, just gulping up whatever Amps the solar panels can supply and coming up to equalising level around morning tea time on a sunny day. But I too am still babying them a bit, doing some load shedding if it looks like being overcast for a few days in a row. Klaus |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
Called in for a cuppa and a quick check on the battery bank yesterday on the way past. Almost perfect timing, they had used a lot of power on Sunday and when I got there it was cloudy-ish and cool and they had been using a couple of angle grinders, a cutoff machine and a paver cutter for most of Monday morning. Batteries voltage when I got there around 10:45am was 27.6 (3.45/cell), that is as full as they will get with this old solar controller's limit settings. the batteries have been installed for more than 4 months without being pushed into balancing voltage range so it was time to take some proper measurements. While there was a small gap in the clouds I quickly fitted a bypass jumper to the controllers terminals, within 40 seconds the bank voltage was above 29.2 and all the bypass shunt red LED's were lit which says they are at their 2 amp max. I dialed it back to roughly 28.8 and took some voltage readings five cells were at 3.605 one in the middle of the pack was at 3.569 and the two on the negative end tested 3.555 and 3.549 Max difference of 0.056 volts after 4 months. In theory, the way it is working ATM the cells COULD potentially spread 0.2 (0.1 volt either side of the pack average) before the shunts start to shift power away from the highest voltage cells. We are under 30% of that mark after 4 months. I am pretty chuffed, I may have almost broken into a happy camper's dance and a couple of subtle fist pumps while no-one was watching  not that I would ever admit that in public I'm confused, no wait... maybe I'm not... |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
In the next month this little system will get an upgrade. the addition of 6Kw of panels and a Midnite solar Classic 150 (with a whizbang Jnr and shunt). The twist is that it will be split into two 3Kw sections, angled at 50+ degrees from horizontal and facing east and west in an effort to maximise winter production and stretch it over the maximum time during the day. there will be the addition of two new separate 240V ac supplies that will be relay controlled in response to the battery SOC, power being used and potential power available. Anything that stores energy will be hooked to these circuits (cordless tool chargers, air compressor, water pumps) The panels will be series paired rather than 3S to keep the voltage down and only 4 Kw will be hooked to the new controller, keeping it to around 85 amps max. (its a 25 volt system) Ideally I would like to orientate the panels 10 degrees north of true east and west but the mounting structure I have may prevent us from doing this. With the small existing solar system, total potential output will be in the range of 23Kwh to 50Kwh per day. with a very flat output curve right from a few minutes after the sun rises until sunset. 9 hours of potential sunlight in winter up to 13 hours in summer. If I ever get my camera back I will take a few photos. cheers Yahoo I'm confused, no wait... maybe I'm not... |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
I've wondered if it would be beneficial to break up a array and face some panels east, and some west, especially if you have more panels that you can use at midday if all the panels were facing north. It would also work better if the weather is a bit damp. Chances are early morning, or late afternoon, you would get clear skies, and a few panels facing the low sun would soak up more amps than a full array set up for the midday sun. Be interesting to see how this goes Yahoo. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
I'm confused, no wait... maybe I'm not... |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
I finally lost patience waiting for some specific DC breakers I ordered to turn up and have installed the first third of the east/west panels. flicked the switch on the solar controller about 50 minutes before sunset on a fairly dull day and the panels were pumping 15 amps, at the same time the north facing panels were at 2 amps. Nice start! The next day was gale force winds and rain so I wasn't expecting anything spectacular. Anyway when I rang this morning I got told the voltage had been at 29 volts before 9.30am, this had me puzzled because it has never been that high as it is set to 28.3. I was a little worried that the voltage calibration of the new controller might be not accurate, however I finally worked out it was the combination of the battery being fully charged earlier in the day, the controllers temperature compensation is still switched on AND it was a particularly cold day. The batteries are not normally charged this early. Ha! cold mornings, who would have thought!! 
So we have tweaked the controllers back to 28 volts, the temp comp is still switched on. The temperature will have to be below 8deg C to get above 29 volts now. I'm confused, no wait... maybe I'm not... |
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| M Del Senior Member  Joined: 09/04/2012 Location: AustraliaPosts: 155 |
Hi Yahoo, it seems you are very happy with this battery set. To increase the amperage this battery type seems to be a good candidate for series parallel configuration, where as LA can require a bit more effort to operate dual banks without resorting to multiple equalizing activities. This has been a very informative thread, thanks for the information. Mark |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
Hi Mark, I am not a fan of parallel banks, I have even less enthusiasm for paralleled cells, if it is designed to last 5-7 years it would be fine but I can see some of the systems I install still being around in 12-20 years, hopefully with the same batteries. If the cells are paralleled the wiring needs to be as close to perfect as possible, the slightest bit of resistance can throw thing out of whack. that really means busbars and soldered connections. In a situation where one cell is higher than the rest it has got to get to 4 volts before this BMS will shut things down, I start to wonder how many times it could have been high before that and how much damage has been done. The thing I have noticed with the pre-programmed controllers I have played with so far is their stubborn refusal to go to float voltage and their refusal to stay there when they do, Im not sure why this is, they work fine on a WLA. This constant need to top the batteries up is not ideal for the LFP chemistry. I will probably admit defeat on this and swap them out for a morningstar relay driver RD-1 on the old solar panel bank. When I look at this system, I feel we are on the practical limit for 24 volt. The 400Ah batteries have a usable capacity of say 320Ah and can punch out 500amps without raising a sweat. they are a rough equivalent of a set of top quality 800Ah gels or 1100Ah of some cheaper mid range WLA. Sure, I could install a bigger inverter but it wont last and the size of the wiring gets enormous. I would say the better long term option is a 48v,72v or 120v build and stay with a single string of cells. cheers yahoo I'm confused, no wait... maybe I'm not... |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
The last few bits and pieces are turning up for the permanent install. We have splashed a bit of money out on a couple of items but it has saved a few bucks in gear that we do not have to fit and gives us some extra simplicity and flexibility. the solar controller is a midnite solar classic 150, 
it is overkill for this situation as a controller but it has two handy features that I am hoping will justify the expense. the first is a a function called opportunity low on the aux1 output, this should let us switch the second bank of solar panels with a solid state relay at a voltage setting that is set slightly lower than the charge voltage settings on the classic itself. This will give us a two stage power down so that we are not driving the batteries close to the end volts with everything that the sun is throwing at us. likewise the float settings can be staggered as well. the second feature is the software to drive this the whizbang jr 
this is basically a 500A shunt that is connected to the negative battery terminal, the sensor sends the data to the classic. this gives us a couple of things - logging of the total power in and out of the system - state of charge calculations that the controller can use - calculation of battery health - and most importantly, the ability to end the absorption charge on an end amps setting, not just time. This gets us around the problem of the batteries charging differently when they are deep or shallow cycled. Without this bit of kit the classic controller can only see its own data, not the system as a whole. The last item is a morningstar RD-1 relay driver, 
this will be primarily used to switch loads in and out depending on battery voltage but I can use one of the 4 outputs to drive two SSR's as backup charge control. This is just in case the classic 150 needs to be removed and sent away for some reason. With some conservative voltage settings the batteries should run quite happily on the relay driver without balance charge voltages for a couple of months. If it becomes necessary to balance the batteries a pair of 12 volt chargers can be clipped to half a pack each and a manual balance can be done. That's a lot easier than finding a replacement controller at short notice or running a generator 24/7. This is one of the benefits of the LFP bank and the independent Battery Management System I did not foresee, the fact that they can be cycled in the 40% to 90% State Of Charge range for long periods with little or no damage to the cells and no danger to the pack from over or under voltage is a real bonus. I'm confused, no wait... maybe I'm not... |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
Just a note about the solar panel wiring while I think of it. I agonized about getting value out of the midnite classic and using it to its maximum potential for quite a few months when I first considered using them. it is supposed to handle 96 amps and high overvoltage conditions on cold mornings. In this situation I have decided to not push the ragged edge, there is really no need. We are above the charge rate we targeted for the batteries by a small margin and the fact that we have split the panels east / west we could potentially be at least doubling the controllers daily duty cycle. There is no peak at midday, it is just a solid constant availability of power from sunup to sundown. The panels are wired in series pairs (to keep the mppt voltage down)rather than in groups of three and the maximum output from the controller itself will be roughly around 80 amps. The solar banks on the SSR's supply the bulk of the power. Its funny, I still catch myself thinking in terms of squeezing the last drop of efficiency out of the panels and wondering about $ per KwH, even though I have known for a few years that it makes no sense to measure a modern off-grid system this way. cheers Yahoo I'm confused, no wait... maybe I'm not... |
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| Georgen Guru Joined: 13/09/2011 Location: AustraliaPosts: 462 |
Add a bit for daily connection fee and this way you can roughly calculate cost/savings. For me off grid would be bit too much worry, as should anything go wrong I would cope heaps. Personally I could adjust to power usage limitations, but some get used to luxury of having it 100% of the time. George |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi George I think back to the old days when we had three kero lamps and a Koolgardi meatcooler and where living with a wind up gramaphone and an old piano for music, then Grandpa put in a 32 volt lighting system driven off the milking machine and a 32 volt fridge he made, we thought we where king of the farms, then came a 32 volt radio magic to hear. Then came the washing machine with a villiers motor under it, when that died Grandpa replaced it with a 32 volt motor what a leap forward that was. We have progressed a long way from there in conveniences but the awe and appreciation has turned into a "must have" at all cost expectation, it is good in some ways but it costs a lot to buy and keep up with and run, and you loose the sense of adventure we had all those years ago, I call us spoiled but poorer for it. All the best Bob Foolin Around |
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| brucedownunder2 Guru Joined: 14/09/2005 Location: AustraliaPosts: 1548 |
Hi Bob and crew, Our mob had an ice chest ,nicely crafted out of polished cedar with big bright brass hinges and handle turning catch .. I remember dad used to pile us kids into the back of the ol Whippet (that was a flash car in them days-for you young whipper snippers), and off we'd go down to Woollongabba ice works for the weeks ice block. Our mob had a dairy farm up outside Toowoomba ,a place called Biddeston , and I remember the 32 volt lighting plant. Gee ,that fresh full cream milk straight from the chiller was great-- pure milk ,not todays junk!. Our Cooparoo streets were dirt in them days ,just Chatsworth road was tarred. Our fruit and vege man,Mr.Spence, had a horse drawn cart and he would enter the weeks take into his notepad and Mum would pay him on Navy pay day-even the local shop kept a book for Mums groceriers. People were dead set honest in those days . I remember hooking up my crystal set to the clothes line --a long wire strung between the house and our pointseanna tree , propped up with a prop we 'd cut down up at whites hill while catching Yabbies in the creek-all posh houses now. Cheers , Bob Bruce Bushboy |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Bruce et al Your experiences are much like mine at the time, we had it good on the farm as we grew everything we needed except for a few staples and every 3 months Grandma would hook up the horse and wagon and we would go to town, "Wangaratta" in Victoria it was a whole days trip in the wagon then stay overnight in the hotel for a few shillings off to the farmers coop and load the wagon in the morning and head home. I was only four at the time but remember it vividly it was a real adventure for a toddler, Uncle had a T model ford but grandma and grandpa didn't drive so used the horse and wagon. This was not all that long ago 1949 / 50. She would take the .22 rifle to get a few bunnies on the way to eat or trade at the coop. When I look at whats available to us now as compared to Grandpa's time, we have so much potential to live a simple life with modern conveniences, but unfortunately the keep up with the Johnson's syndrome is actively promoted by advertising of the latest and greatest wiz bang gizmo that lasts two days longer than it's warranty. Everything is better now, roads, cars, technology, communications, but the moral values have fallen away, now we lock and bolt down things and fit security systems to protect our treasures, when in the old days the dog was the security and not to attack anyone, just to act as a door bell cause we didn't have one, no locks on the doors keys rusted into the ignition lock of the car. We had a 5 valve radio HMV made in Australia as we where to far from town to get a crystal set to work, grandpa cut timber for a whole week to buy that radio and it was still going in 1978 when they rebuilt the house, Uncle got married so needed more space. The good old days that have gone but we still have the good days now if we do things in a organized way. All the best Bob Foolin Around |
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| Georgen Guru Joined: 13/09/2011 Location: AustraliaPosts: 462 |
In NSW you get fined if Police finds unlocked car. So it is assumed that thieves are around and you must protect yourself or else. George |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi George Police will use any excuse to extract money from you, it is a shame that we have progressed very well in the technology and learning fields but regressed badly in moral and life skills. We should be talking about how we can use the available technology to increase our independence and hopefully in some way to lessen the cost of survival, the LIPO batteries is a good opportunity for this and I wait for a realistic proven examples of cost effective time trials, after all the initial cost is only a starting point and it boils down to the usage over time to establish real world costs. In our lives we waste thousands of dollars on throw away products from the latest sound system or TV to out shiny chariot and think nothing of it but quibble over a few watt dollars on our life support system. namely our battery systems. All the best Bob Foolin Around |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
I have taken the opportunity on a cold and miserable day to swap the old PWM solar controllers out and replace them with the Classic 150 and whizbang junior. the higher voltages with the cold weather was making me nervous. I figure disabling the temperature compensation on them is just not worth the effort. It was a good day because the cloud and intermittent sun meant I could sit and watch and tweak things under a variety of conditions. A pretty trouble free install, replaced a few cable lugs and lengths of heavy wire that was not long enough to reach where it was supposed to. I rolled through the settings menus in about 5 minutes, disabled the temperature compensation, enabled the external shunt monitoring. I got slightly caught finding where to set the battery size and charge efficiency, there is a screen hidden behind the whizbang shunt status screen called setup, it is not in the main menu tree....and I had to look up the manual to get and explanation of how to set the "return to charge from float" (called rebulk). I switched a bank of north facing panels on, the controller come out of resting mode and straight into absorb, I think I looked away to zero my clamp meter and when I looked back it was in float. Oops! well the batteries are full so I switched the panels off, fired the inverter back up and switched a heap of things on in the house to make a bit of room in the batteries to have a play with the voltage settings.
The first thing I found when I connected the north facing panels and the east / west panels at the same time, I was getting some backfeeding through the east/west panels. I didn't leave it running and have a poke around to see exactly where it was going because it was upsetting the classic 150, the charging amps were cycling up and down and dropping to zero and restarting every ten seconds or so. I had a bit of a think about it and probably the easiest fix is to solder in some diodes where the wires from the separate banks of panels come together at the PV circuit breaker enclosures. So after some testing the volt settings are now Absorb 27.9 (3.4875 per cell) timer 2 hours or 4 amps endpoint on the whizbang shunt. float 26.8 (3.35 per cell) rebulk 26.0 volts Just before I left this afternoon we got a bit of decent sun and I got a complete cycle from bulk to float on the data logger. The voltage rose very rapidly above 27.55 volts so it looks like the Absorb volts could go lower, somewhere in the 3.44 - 3.45 V per cell range could give me the margin below 100% SOC that I am looking for. The 4 amp end point is well below the recommended 20 amps (0.05C) that the EV guys use but it reaches this point in less than a minute after the charge controller starts limiting voltage. I guess I will tweak it again if I lower the charge voltage. I watched it in float for 15 minutes after the volts drifted down and there was no charge or discharge on the battery bank, all the loads were supplied directly from the panels so I am very happy with that setting ATM. I haven't programed a balance cycle on the EQ settings, we have decided to manual balance for the time being, the next one is in two months when the BMS and contactors are next due to be cycled and checked. 
So there you have it! Not as exciting as watching paint dry but it had its fleeting moments I guess.  I'm confused, no wait... maybe I'm not... |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
Hi George, It really pains me that you have spent three and a half years on this forum and still fall for dodgy accounting. The DIY ethos here is all about adding value and quality to your life on a budget not just finding the cheapest short term fix. Do you see those adverts on the TV, $49.99 for some gadget, if you are the first 90 callers you get an extra one free. the first reaction is AH-HA $50 divided by two is twenty five dollars each, that is half price. But if you think about it a little longer, -You have still paid $50, they still have your money, -what are you going to do with a second one that actually adds value to your life, and lastly, if their production and marketing costs work out to 20 cents per item their additional costs for this wondrous offer is more like 0.04% so even one hundredth of a percent increase in sales from this marketing hype on a $50 item will net them a tidy profit. It is the same with a fully integrated solar system, only the opposite way around. I quoted a job 3 years ago and planned a total strategy that would cost them $11,000 of capital expense and increase the cost of electricity for them from 29 cents per Kwh to 31 cents per Kwh over ten years. That does not make any sense at all does it? Spend all that money and the price of power goes up! Looking at the data 3 years later, their combined financial cost for the capital and electricity bill is $1600 per year, down from $5880/yr for electricity beforehand. They are still running a heated indoor pool, 5 TV's etc, etc, etc and no gas or wood used for cooking or heating so their standard of living is the same or better than it was, plus they now have an extra $4000 in their pocket every year. Here is some light reading from Jack Rickard about the reality of fossil fuels and cars Vs solar power and electric transport and how the current business model works. Where the sun dont shine He can be an abrasive pain in the bum BUT he knows how business works, in this post he is giving us a little glimpse at the future. He sees the same thing I see, the business model for centrally distributed power is flawed and ultimately will not survive the battle with solar energy. No argument against solar power will stop the inevitable because the alternative is worse! You dont have to have panels on your roof and an electric car in the drive, you just need to be aware of how the money that comes out of your pocket on a regular basis shapes the world around you and see the REAL value that it brings. That is all it takes to change the economy, faced with two options, you chose the blue pill instead of the red one.
Go and have a wander down the aisles of a big chain store and look at all the poor value products on offer. Is any of your superannuation money financing this business structure? Look at all the business models that prey on poor people with ongoing debt and tricky repayments. Look past the piece of furniture or white-goods and think about the repayment plan or the concept of payday loans. Sit in the bar of a pub that is run as part of a chain and look at racing on the wall of TV's and listen to the sound of pokies from the next room, think about where the revenue is going. Think about what it means for a spud grower to not dig his potatoes and sell them at six cent/kg when the price in the supermarket is $2.44/kg. How many growers do you bankrupt before the business model collapses altogether? The current thinking is there will always be someone to take his place so it can carry on. Does funding health care for diet related chronic disease make more financial sense than offering an alternative that prevents the condition in the first place? In our modern thinking it is cheaper per person to treat three million people with metabolic syndrome/diabetes than if there was only ten thousand sufferers, prevention is not even a budget item in the equation. Do you truly believe that digging up iron ore and gas at ever increasing amounts and selling it at bargain basement prices on borrowed money is going to end well for Australians? Ultimately it is your and my money that funds all this. Contrary to Bob and Bruce, I think that the "good ol days" are still here, you just need to dig a little harder, crunch the numbers properly, do a little research and make some sensible choices and scrutinize how your hard earned $$ are being spent (and think just a little outside of the conventional box occasionally). cheers Yahoo I'm confused, no wait... maybe I'm not... |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Yahoo2 There are many issues to be faced in our present environment, most of which are in our own expectations, and keeping up with the tread wheel we all place ourselves in, that's been carefully generated by advertising and peer pressure created expectations from within, this is a steady insidious progression of our society, and I have to agree with you that the good old days are still here for this generation, when they look back over their life in the future,they will also see these days as their good old days, but you must remember we look back at our good old days some fifty years or more in the past, I bought my first house for 5K my son bought his first house for 450K, got out of work and lost it in the first 2 years, and we see our good old days for what they where, a simple and manageable and affordable way of life, I am sure that the young ones will look back at simple way of life as they perceive it to be now, some fifty years in the future again. Looking at the struggles of my children and grandchildren to make a comfortable place for themselves in society, it really makes me sad to see how their efforts and expectations are being used by commercial interests to fleece them of everything they have worked for, they have lost the opportunity for self advancement, and unless they have a uni degree in something will remain poorpers for the rest of their lives without the pleasure to experiment with various ways to help themselves and their families as we have been able to enjoy over our lifetime. You hit the nail on the head when you mentioned crunching numbers as that is the new survival regime in these good old days. And the ability to think outside the box is depleted by rules and regulations and the need to do extra work to generate the dollars needed to support their must have life style. A new BMW that will depreciate 30K when you take delivery of it and it is more essential than buying a set of batteries and some solar panels to save some of their hard earned cash. But I am just an old dinosaur they tell me, what would I know about their situation, must have a new 3d TV to watch the sh*t in 3d and must have a pool in the back yard, it only costs a hundred dollars a week to run you know. and the bank gave them the money because they have a bit of equity in their house, "Caused by Inflation" but it is getting hard to feed the kids on two wages have to do some night work to make up the extra dollars. This is their good old days? All the best Bob Foolin Around |
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