September 4, 20205 yr Author The beast is complete and charging! Sparky didn’t show his face once to let me know that I had messed up the connections .... good thing. so on to the cabinet to and some dubious welding.
September 5, 20205 yr That is just plain awesome! I’ve been catching myself watching guys on YouTube making these battery packs and it’s fascinating!
September 6, 20205 yr Author Another busy day. Got the material to build the battery rack inside the cabinet (I will be honest and I have gone overboard on the structural strength end of thinks !) I thought I would do a sketch of the plan but that didn’t happen. The plan has remained between my ears and is finding expression as I go. I will hope for the best.
September 6, 20205 yr Very impressive Mike! Thanks for sharing. Missed your build last year so I'm happy to read it now!
September 6, 20205 yr Author 1 hour ago, RikH said: Very impressive Mike! Thanks for sharing. Missed your build last year so I'm happy to read it now! @RikH thanks, the build has definitely been a great deal of fun. I look back at what was a battery to extend the UPS on the computer, then after watch a zillion youtube videos then thinking to myself I will build just a small 24V system to keep the gate and alarm system powered... well I am now at a 48V system and asking myself if I shouldn't just build a battery shed to fit a small 100kWh battery, cover the entire roof in solar panels...... just a few mods that the wife will not notice!
September 8, 20205 yr Author I little progress has been made with painting the battery racking system. As usual the word over done comes to mind; I went to town with applying undercoat paint to the steel which was wiring brushed, then acid cleaned and finally the grinding disc was used. with the undercoat done another 2 coats of brilliant white (door frame paint) was used. Why the undercoat and door frame paint I hear you ask! Well because both tins have been sitting in my garage for nearly 2 years and surprising seem to be in okay condition. tomorrow I will throw on another coat just to polish of the paint. Edited September 8, 20205 yr by Mad Mike
September 19, 20205 yr Author Well it has been a week of slow progress but finally the beast is back online. We have Gotten so intimate that I had to name it! Stima it is, 320P 14S 18650 pack with an average Individual cell capacity of just over 2000mAh. i am done with this battery and will be turning my attention to the other inverter.
September 19, 20205 yr On 2020/09/04 at 2:19 PM, Mad Mike said: Did you change your BMS that you used. The BMS that you showed last did not have any comms from what I can see, while this picture does show data from the BMS. Why I am asking is that this looks like the Apple app for the BMS I wrote the Venus OS Serial-Battery driver for. Nice work on getting the battery completed. Looks like something that will take a lot of time and effort.
September 19, 20205 yr Author 3 hours ago, Louisvdw said: Did you change your BMS that you used. The BMS that you showed last did not have any comms from what I can see, while this picture does show data from the BMS. Why I am asking is that this looks like the Apple app for the BMS I wrote the Venus OS Serial-Battery driver for. Nice work on getting the battery completed. Looks like something that will take a lot of time and effort. @Louisvdw I did change the BMS (same manufacturer, upped the max current added the Bluetooth module). The BMS is from China so I would say no your work being “borrowed” without permission! the battery has taken some time to build...about 18months. The battery is actually 4no. 80P 14S each built And commissioned to the same Goodwe inverter separately with the end goal of shoving it all Into the server cabinet.
September 20, 20205 yr 15 hours ago, Mad Mike said: I would say no your work being “borrowed” My driver is free to use. It just means that if you ever "upgrade" to a Victron system, then you can use the driver for the battery to talk to the Victron system. The driver was written for the LLT Power smart BMS. The app is called XiaoXiang BMS. https://apps.apple.com/us/app/xiaoxiang-bms/id1375405426https://play.google.com/store/apps/details?id=com.jiabaida.bms&hl=en
September 20, 20205 yr Author 28 minutes ago, Louisvdw said: My driver is free to use. It just means that if you ever "upgrade" to a Victron system, then you can use the driver for the battery to talk to the Victron system. The driver was written for the LLT Power smart BMS. The app is called XiaoXiang BMS. https://apps.apple.com/us/app/xiaoxiang-bms/id1375405426https://play.google.com/store/apps/details?id=com.jiabaida.bms&hl=en @Louisvdw you are swearing at me “upgrade to the blue yonder” ! I am a yellow line “Goodwe” man! You would have my lifelong gratitude if you wrote a driver for the goodwe..... be a good sport and write the code for the Goodwe. i cannot be the difficult really, a line of code here a little grey hair there😇......
September 20, 20205 yr LOL! I only have Blue stuff to test on. There is nothing Yellow in my house. If someone can write code to talk the yellow inverters, then I can assist with the battery part.
September 20, 20205 yr Author 24 minutes ago, Louisvdw said: LOL! I only have Blue stuff to test on. There is nothing Yellow in my house. If someone can write code to talk the yellow inverters, then I can assist with the battery part. Hen’s teeth and honest government will come first I fear! But I live in eternal hope that you will see the error of your blue ways and come over to the yellow side (drivers, cables and battery bits in hand) amen!
September 20, 20205 yr Author @Louisvdwnow that I have you on the line, the app has a limit on the Ah that the battery can be..... my little battery Has put on a little weight and now has a theoretical Ah of just over 9400Ah. Any chance that your next update to the software would accommodate us outliers? Pretty please!
September 21, 20205 yr S 17 hours ago, Mad Mike said: Any chance Sorry Mike. That is not my app. But I do see you can log issues for that app on their Github page. https://github.com/smagicld/xiaoxiangBMS/issues
September 21, 20205 yr Author 39 minutes ago, Louisvdw said: S Sorry Mike. That is not my app. But I do see you can log issues for that app on their Github page. https://github.com/smagicld/xiaoxiangBMS/issues Thanks for pointing me in the right direction! I will definitely go and whine and complain there.
September 23, 20205 yr Well done. That is some super work. Did you ever do a calculation of the cost - materials, time spent on making that battery bank? Would be interested in seeing the cost compared to a ready made lithium solution.
September 23, 20205 yr Author 39 minutes ago, randomwalsh said: Well done. That is some super work. Did you ever do a calculation of the cost - materials, time spent on making that battery bank? Would be interested in seeing the cost compared to a ready made lithium solution. I have actually done the cost on the project and let's just say that it isnt cheap.... Let's Assume an R450/hr labor rate Shelling the laptop batteries and cleaning the 18650s 14hrs (here I assumed that even the low capacity cells were going into a low capacity powerwall eventually) = R6,300 Capacity testing (just the loading and unloading into the testers and labelling 1 min a cell - actually timed this...) 18hrs =R8,100 Soldering batteries packs 28hrs =R12,600 Cost of 18650s @R5 No 4480 = R22,400 Miscellaneous (welding cable, soldering guns, solder, fuses, 18650 battery holders, server cabinet, rack, busbars, BMS) R=10,000 so for my theoretical 33kWh ( have conservatively derated this to 28kWh) powerwall I am R59,400 in the hole and counting! if you take out the labour of love and pain cost..... If you look at Revov for secondlife batteries 10KWh is R45,000 so 30Kwh would be R135,000. It is a toss up as to whether zero warranty (ie you are the warranty) is worth paying a third... so far I would have to say i am pretty happy with the outcome so much so that I am prepping for my next build. I definitely want to build several Tesla type (in form factor) powerwall to use on my second Goodwe inverter.
September 24, 20205 yr Author I have been asked how the battery pack has been behaving thus far and i think the only way to really show this is to share the inverter logs from Goodwe. I have shared from the 20th of this month the day after I put the system back online. Just a few notes to make; the house has been split into two main circuits (that job was a revelations of the rat's nest of wiring I had in the ceiling and original DB) with two independent inverters. This DIY battery pack supports 50% of the house and all the security and perimeter lights the second inverter supports the living space and kitchen, that one I haven't made any changes to yet. so that said the DIY battery has been chugging away nicely and the supported load have been 100% solar and battery supplied (ESKOM has been officially given notice to vacant that space!). I am extremely happy with the outcome and now I am truly motivated to tackle the second battery pack. I think I will have a "lightly used" pylontech battery for sale within the year! PV status.pdf
December 23, 20205 yr Truly amazing project! It seems from the pictures that you have directly soldered onto the battery cell terminals, is the Lithium cells OK with handling the soldering temperatures? Take it that, based on the performance of this mega battery, that the cells seems OK with the temperatures.
December 23, 20205 yr Author Let’s just say that the batteries haven’t don’t anything in the way of burning their fuses, pulling the packs out of balance or burn down the house in protest (knock on wood). the exercise of soldering the individual fuses still brings back flashes of hours spent bent over swearing at each cell and the accompanying fuse! when I win the lottery I will be buying the kweld to spot weld the fuses on....
December 23, 20205 yr 36 minutes ago, Mad Mike said: 36 minutes ago, Mad Mike said: the exercise of soldering the individual fuses still brings back flashes of hours spent bent over swearing at each cell and the accompanying fuse! 😀 can imagine! Hopefully it was lead-less solder wire!
December 23, 20205 yr I missed this build.. (the title wasn't that accurate..) This is on my list of 'things to do...' Not to compare but I stumbled on this DavidPoz video:
August 20, 20214 yr Author Finally got my second Powerwall nearly done, need to tidy up the wiring and fabricate the panels to enclose the battery then to roll it into its new home in a little fire proof should it loss its mind and go nuclear on me! But so far so good. As with the first Powerwall it is a 14S setup but only 240P. the usual... finding of the used 18650s, testing them, soldering and fusing every one of the cells brings tears to my eyes and sweet words for each cell done! I will hopefully find a few more of the pictures taken at various stages through the last 12 months and post them here. IMG_2526.heic
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