PurePower Posted September 22, 2017 Share Posted September 22, 2017 Hi Gents, How feasible is this??? I've seen plenty of youtube videos and forum posts saying that its all possible. But in real terms... is it sustainable and safe for long term use? Check out the below links for more info... https://www.youtube.com/channel/UC0pBauLp63yzf6sVdEOIUbA https://hackaday.com/2016/09/29/homebrew-powerwall-sitting-at-20kwh/ https://motherboard.vice.com/en_us/article/kzz7zm/diy-powerwall-builders-are-using-recycled-laptop-batteries-to-power-their-homes https://greentransportation.info/ev-batteries/diy/18650-powerwall-clone.html There is an entire forum dedicated to this: http://www.diypowerwalls.com/index.php Has anyone in SA attempted this? Is anyone willing? This seems to be an interesting topic , comments will be appreciated. Quote Link to comment Share on other sites More sharing options...
Chris Hobson Posted September 22, 2017 Share Posted September 22, 2017 I was considering it. It is as safe as the BMS you use. There are instructions on a DIY BMS on the AEVA forum. Since @Coulomb was involved I willing to say it is top notch. The Karoo is a long way from a source of secondhand 18650 cells. I think the reason I eventually canned the idea was that you would tinker with it forever replacing cells as they age.Plus you going to spend a fair amount of Tom on all the fiddly bits. You will build it cheaply but need to factor in your time. With the rumbles of thunder I think I am about to get busy so instead I am now getting ready to raid the piggy bank for some Pylontechs. Quote Link to comment Share on other sites More sharing options...
PurePower Posted September 22, 2017 Author Share Posted September 22, 2017 I'm struggling to understand what the battery make up convention like 80p14s; does that mean 80 cells in parallel and then 14 strings? Totaling to 1120 cells? Quote Link to comment Share on other sites More sharing options...
Chris Hobson Posted September 22, 2017 Share Posted September 22, 2017 l 1 hour ago, PurePower said: I'm struggling to understand what the battery make up convention like 80p14s; does that mean 80 cells in parallel and then 14 strings? Totaling to 1120 cells? Looks about right. I know Pete from HBPowerwall had 80 cells in parallel and 7 packs in series for a 24V system. Charging to 4.2 V that would give you 58.8V. I would be inclined to charge to 4.1V or 57.4V. Yes you would have less capacity but just build a bigger bank. Quote Link to comment Share on other sites More sharing options...
Mazs Posted September 22, 2017 Share Posted September 22, 2017 There is a real risk of starting a fire. I would not dare try this in my house. Quote Link to comment Share on other sites More sharing options...
seant Posted February 8, 2018 Share Posted February 8, 2018 It's doable , very time consuming breakung up packs , charging , discharging, testing , waiting and then test again. It took me about about 4 months to put together a 182p14s 17Kwh battery pack. pilotfish 1 Quote Link to comment Share on other sites More sharing options...
pilotfish Posted February 8, 2018 Share Posted February 8, 2018 29 minutes ago, seant said: 182p14p 17Kwh battery pack. I am guessing 182s14p 182p14s... I would love to give that a go - where did you find 2548 cells, what did it cost, are you using a BMS, are you happy with the resulting performance? Quote Link to comment Share on other sites More sharing options...
seant Posted February 8, 2018 Share Posted February 8, 2018 On 2017/09/22 at 10:57 PM, Mazs said: There is a real risk of starting a fire. I would not dare try this in my house. But your cell phone and laptop etc all with diffrent lithium battery chemistries and no fire as of yet I take it. Talking about things that go bang what about the off gassing from the lead acid batteris in a small room . There is a potential for a lot of things to catch fire and worse. If it goes wrong Li-ion cause a nasty fire and there isn't too much you can do to stop it . Use a bit of common sense , like you said don't put it in your house , don't use dodgy batteries and keep an eye on the battery packs and all should be fine Quote Link to comment Share on other sites More sharing options...
seant Posted February 8, 2018 Share Posted February 8, 2018 It took quite some searching but I ended up getting a pile of the same cells from someonewho was scrapping some electronics. I haven't got a BMS yet but that's on my list. Fortunately as they are all of similar capacity the keep themselves quite well in balance within about 0.08v of each pack. As for the capacity and performance , I had a 48v set of batteries from a forklift and the Li-ion battery works extremely well compared. Chris Hobson 1 Quote Link to comment Share on other sites More sharing options...
pilotfish Posted February 8, 2018 Share Posted February 8, 2018 Any hints as to where to look for the cells? Quote Link to comment Share on other sites More sharing options...
seant Posted February 8, 2018 Share Posted February 8, 2018 Check with companies who recycle/scrap electronics. You'll probably pay some where between R20 and R50 an old laptop pack pilotfish 1 Quote Link to comment Share on other sites More sharing options...
Chris Hobson Posted February 8, 2018 Share Posted February 8, 2018 1 hour ago, seant said: But your cell phone and laptop etc all with diffrent lithium battery chemistries and no fire as of yet I take it. This is not quite true. Each chemistry has its own thermal runaway The earliest Lithium chemistry was Lithium cobalt and has a thermal runaway temp of 150°C . This low thermal runaway temperature, poor cycle life and the high cost of cobalt has resulted in this chemistry being replace by blending manganese with other active materials for the cathode Lithium manganese oxide was one of the first replacements of lithium cobalt with a thermal runaway of 250°C. Like lithium cobalt rapid charging can lower this figure. It also suffers from a shorter cycle life. Lithium Ferrous Phosphate with a thermal runaway of 270°C can safely be stored fully charged. It has excellent cycle life and is one of the safest chemistries. With a max charging voltage of 3.65V it does not have the same energy density of other lithium chemistries but that is not a major factor in the solar industry. Lithium Nickel cobalt aluminium oxide shares many characteristics of lithium cobalt but is cheaper and has a longer cycle life Thermal runaway is also about 150°C Lithium nickel manganese cobalt oxide (NMC) is one of the newer cobalt blends results in lowering of costs and better safety (thermal runaway of 210°C ) making it a favoured chemistry of the electric car industry. Lithium Titanate no thermal runaway problems and has a high cycle life but cost are high and is largely limited to the electric car industry. pilotfish, Coulomb and ___ 2 1 Quote Link to comment Share on other sites More sharing options...
___ Posted February 8, 2018 Share Posted February 8, 2018 2 hours ago, Chris Hobson said: Lithium Nickel cobalt aluminium oxide Some car manufacturers are looking at this one because of the lower cost. It does however sport lower energy density as well, so NMC is still preferred. For house applications, the top contenders remain NMC (I believe the Daimler and Tesla batteries are NMC) and LFP, although again a case can be made for NCA, because NCA is cheaper than NMC but has better energy density than LFP. Or at least... that's how I understand it. Chris Hobson 1 Quote Link to comment Share on other sites More sharing options...
Mark Posted February 8, 2018 Share Posted February 8, 2018 2 hours ago, Chris Hobson said: This is not quite true. Each chemistry has its own thermal runaway One of my friends brother was fiddling with a small PV system with old laptop batteries... don't have technical details so can't comment on what happened but in short... his house (the whole thing) burnt down in November! ... the wife just managed to get out in time. They lost everything! So rather more careful than not... if you watch the HBPW and the other Auzzy guys they all have a battery shed apart from the main house - for good reason. Chris Hobson and ___ 2 Quote Link to comment Share on other sites More sharing options...
Guest Posted February 8, 2018 Share Posted February 8, 2018 5 hours ago, seant said: But your cell phone and laptop etc all with diffrent lithium battery chemistries and no fire as of yet I take it. O nooo. After a 2 sec Google, for I remember the drama about cellphone batteries and fires and explosions recently. https://www.cbsnews.com/news/lithium-battery-fire-risk-samsung-galaxy-note-7/ Quote Link to comment Share on other sites More sharing options...
___ Posted February 8, 2018 Share Posted February 8, 2018 8 minutes ago, The Terrible Triplett said: After a 2 sec Google, for I remember the drama about cellphone batteries and fires and explosions recently. The Bee had a really really good satirical article on it. Can't remember the last time I laughed so hard. I figure I can post that here seeing as we do occasionally venture over to that side... and I love humour of all kinds. If you can't joke about yourself... why bother? Mark and Chris Hobson 2 Quote Link to comment Share on other sites More sharing options...
seant Posted February 8, 2018 Share Posted February 8, 2018 I've seen a cellphone battery explode while being charged, the phone ended up up on one side of the room and the battery casing embedded in ceiling. And people still charge them next to their beds when going to sleep. Still there is tons of info out there on how to build your own powerwall and make it relatively safe. Recycle and reuse a stack of batteries that would otherwise have ended up in a land fill and have a relatively cheap Li ion battery pack, that suits me quite well. Quote Link to comment Share on other sites More sharing options...
SilverNodashi Posted February 14, 2018 Share Posted February 14, 2018 So, how's your lithium battery holding up? Quote Link to comment Share on other sites More sharing options...
seant Posted February 18, 2018 Share Posted February 18, 2018 So far very well. Six months down the line the packs all stay well balanced and it hasn't burst into flames . It delivers the power I need and I couldn't ask for more Quote Link to comment Share on other sites More sharing options...
SilverNodashi Posted February 18, 2018 Share Posted February 18, 2018 6 minutes ago, seant said: So far very well. Six months down the line the packs all stay well balanced and it hasn't burst into flames . It delivers the power I need and I couldn't ask for more please send me some more details about your battery pack? Quote Link to comment Share on other sites More sharing options...
seant Posted February 18, 2018 Share Posted February 18, 2018 8 minutes ago, SilverNodashi said: please send me some more details about your battery pack? Sure, I built a roughly 17Kwh 48v battery pack from 18650 batteries which I recovered from used battery packs , there are 14 packs in series and each pack is made up of 182 batteries in parallel. Each 18650 cell has a capacity of approximately 1800mAh. Each cell is soldered to a buss bar with a fuseable link . As soon as the budget allows I'll add a BMS but in the mean time I keep a close eye on the battery pack voltages. Quote Link to comment Share on other sites More sharing options...
Mars Posted February 19, 2018 Share Posted February 19, 2018 Maybe you can post some photos for full pack and close ups ? Are you using inverter for charging ? Axpert ? Can you share settings ? Quote Link to comment Share on other sites More sharing options...
seant Posted February 23, 2018 Share Posted February 23, 2018 Here are a few photos of my diy powerwall. PurePower, ibiza and Youda 2 1 Quote Link to comment Share on other sites More sharing options...
seant Posted February 23, 2018 Share Posted February 23, 2018 At the moment I use a flexmax80 as a charge controller and a salvaged 5kva APC ups. The UPS is a bit power hungry but it works . I'm still deciding what brand of inverter to buy . I don't like the voltronic products they seem temperamental and prone to a variety of problems. I kind of fancy the Outback Radian hybrid inverter but I can't find much local support for it, so the search continues. Quote Link to comment Share on other sites More sharing options...
seant Posted February 23, 2018 Share Posted February 23, 2018 The start of the pack resting on top of my old set of traction batteries. And then the box all closed up. Youda 1 Quote Link to comment Share on other sites More sharing options...
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