Been following this forum from the shadows and quietly watching and learning. Finally I took the plunge!

Bought 120kg of laptop batteries ( areal leap of faith!), 3 Liitokalla Battery capacity tester, 4 lithium battery chargers, pliers, soldering gun, solder, PVC piping (initial battery holders), 5x4 18650 holders from china, 7s BMS from china, server cabinet, multimeter, glass fuses and the list goes on and on!

The hardware at hand was, 24V 2400W inline UPS and an unlimited amount of foolhardiness. I will post some pictures of the current temporary setup, was forced to put it in production to keep the lights on! The house has not burnt down just yet so i will push on in getting the system properly assembled and connected to the DB.

7 hours ago, Mad Mike said:

Been following this forum from the shadows and quietly watching and learning. Finally I took the plunge!

Bought 120kg of laptop batteries ( areal leap of faith!), 3 Liitokalla Battery capacity tester, 4 lithium battery chargers, pliers, soldering gun, solder, PVC piping (initial battery holders), 5x4 18650 holders from china, 7s BMS from china, server cabinet, multimeter, glass fuses and the list goes on and on!

The hardware at hand was, 24V 2400W inline UPS and an unlimited amount of foolhardiness. I will post some pictures of the current temporary setup, was forced to put it in production to keep the lights on! The house has not burnt down just yet so i will push on in getting the system properly assembled and connected to the DB.

Mad Mike sounds right.  Come on, don’t tease us, let’s see photos of this home made lithium battery.

its a 24v setup sound like, if you have 18650s in 7S setup?

10 hours ago, Elbow said:

Mad Mike sounds right.  Come on, don’t tease us, let’s see photos of this home made lithium battery.

its a 24v setup sound like, if you have 18650s in 7S setup?

 

 

Edited April 7, 20197 yr by Mad Mike
Better image

10 hours ago, Elbow said:

Mad Mike sounds right.  Come on, don’t tease us, let’s see photos of this home made lithium battery.

its a 24v setup sound like, if you have 18650s in 7S setup?

Yes it is in 7s setup. I did make 14 separate packs (80p) so that when the financial gods smile at me I will get a 48V inverter and reconfirm the packs and put them in series.

That is seriously impressive. Which invertor are you using. How are you charging these batteries ?

On 2019/04/08 at 8:04 AM, MorneDJ said:

That is seriously impressive. Which invertor are you using. How are you charging these batteries ?

I have the “Home UPS 3.6k” a 2400W continuous UPS. The UPS has a solar port that I am told is a 50A and 50V limit. 

i am using the inverter to charge the batteries using eskom power as I gather the financial manuals to buy a change controller and solar panels to get this system Free of Eskom.

the good times keep rolling! since my last update I have added a cheap Chinese BMS and 4 330W Canadian panels to the 2400W Home UPS 3.6k inverter.  I have cycled the setup literally everyday charging up to 26-27 volts and discharging down to 20V. that has been a manual process of turning the inverter own flipping the breaker and through interlocked contactors (so that I don't burn down my pride and joy) running one half of the house and security lights every evening for between 3- 5 hrs. this has run flawlessly and the packs have remained within 0.02V of each other so far. 

just finished cracking more laptop batteries, testing the cells and building another 7s 160p (built as 14 packages of 80p). I have dismounted the first 7s 160p set  i built in May this year, and currently have them all sitting on the floor connected in parallel slowing balancing themselves out. this now brings me to the grand total of 2240 cells averaged at 2000mAh each. There is a set of cells that range from 1600-2700mAh (average is approx 1800mAh) seating in the garage that would potentially give me a third 7s 160p pack but I have my doubts as to whether it will fit in my cabinet with the rest of the other 2 battery banks. for now it will wait.

the highlight of the day yesterday was letting the magic smoke out of two pack fuses by accidentally shorting the packs (nice spark!). That was a 90min job to redo 160 fuses but on the bright side I now know that the fuses work....

I hope to have them all balanced in a day or two before remounting the whole thing back in the cabinet over the coming weekend. then I think i will start the monitoring phase of this whole exercise and see how much money this whole exercise has cost and what it is saving me (apart from the drinking money saved by spending so much time in the garage soldering iron in hand!)

I will post a few pictures in the coming days.

@Mad Mike nice work there. Can you take some close photos how you solder the batteries together and the fuses, and the BMS that you are using. What was the price on the old battery packs?

1 hour ago, Gerlach said:

@Mad Mike nice work there. Can you take some close photos how you solder the batteries together and the fuses, and the BMS that you are using. What was the price on the old battery packs?

@Gerlach, I will post better images this evening for you. 

@Mad MikeLooking good. You must add some links and stuff from where you got all your stuff and what you are using and so on. 

1 hour ago, Gerlach said:

@Mad Mike nice work there. Can you take some close photos how you solder the batteries together and the fuses, and the BMS that you are using. What was the price on the old battery packs?

The BMS is very rudimentary, it has no user interface. The seller indicated that it top balances at 4.1 volts and cuts out at 2.8. I have charged beyond 4volts (28.7volts) and my inverter cuts out at 2.85 (20Volts). As for the balancing I think it works but to be honest the batteries were never out of balance when I run the system for a month without the BMS! 

For the first month I checked the battery packs twice daily (morning and evening) and everything was working well. I will say here that I used repakr to build the packs so they were for all intents and purposes all evenly matched.

7 minutes ago, Gerlach said:

@Mad MikeLooking good. You must add some links and stuff from where you got all your stuff and what you are using and so on. 

Since you have asked so nicely..... 🙂  I will. 

Great stuff. I thinking to take something on like this to. I spotted this BMS this morning. ZAR 544.63 8%OFF | smart display 16S-32S 300A lithium battery protection board balanced management system BMS Coulomb Counter https://s.click.aliexpress.com/e/BkJKTdA

10 hours ago, Mad Mike said:

Since you have asked so nicely..... 🙂  I will. 

@Gerlach , you will have to forgive the untidy soldering!

the battery holders are also off AliExpress. I used the 4x5 pieces. Lost 2 orders courtesy of the post office. I did get a full refund from AliExpress but the time lost and exchange rate losses....

that some hard work and dedication there with all that soldering work.  Do you maybe have a lick for the small fuses, i did a search but cant seem to find them. 

53 minutes ago, Gerlach said:

that some hard work and dedication there with all that soldering work.  Do you maybe have a lick for the small fuses, i did a search but cant seem to find them. 

I believe a search for glass fuses should do the trick. There is a wide selection from 0.5A going up. I opted for 3A fuses just because I didn’t planned to push the cells hard . My please was to draw less than 0.3A per cell at peak. So the 3A was to protect again a cell going into reversal or self discharging spontaneously.

 https://m.aliexpress.com/item/32856407960.html?pid=808_0000_0109&spm=a2g0n.search-amp.list.32856407960&aff_trace_key=54b2b84d62464e49aca10a79cc6fa149-1566282451495-03342-UneMJZVf&aff_platform=msite&m_page_id=8998amp-v3eOzPG_HFh-lg0NQMce2g1566282476878

14 hours ago, Mad Mike said:

@Gerlach , you will have to forgive the untidy soldering!

the battery holders are also off AliExpress. I used the 4x5 pieces. Lost 2 orders courtesy of the post office. I did get a full refund from AliExpress but the time lost and exchange rate losses....

I stopped buying from Alibaba cause they using SA post office. I switched to  Amazon. Their prices look higher than Alibaba but Amazon do the custom charges for you, they deliver the goods to your door step so their price contain everything you need to pay. and they are very fast. I had to wait 8 month for the battery testers  and "kissed them good bye"ordering from Amaxon get them within one week..

5 minutes ago, ibiza said:

Amazon do the custom charges for you

There is some nonsense now about only being allowed to do an import twice a year or something like that, otherwise you must register with SARS as an importer. I don't know to what extent this applies to Amazon, perhaps you do? It's something I will probably have to do some time.

My purchases might go under the radar as they are so small 😀. I  bought several things already with no problems.

Edited August 20, 20196 yr by ibiza

Also got several packages from Amazon and Banggood this year. Plus a few other obscure Chinese sellers. No issues. 

On 2019/08/19 at 11:49 AM, Mad Mike said:

The BMS is very rudimentary, it has no user interface. The seller indicated that it top balances at 4.1 volts and cuts out at 2.8. I have charged beyond 4volts (28.7volts) and my inverter cuts out at 2.85 (20Volts). As for the balancing I think it works but to be honest the batteries were never out of balance when I run the system for a month without the BMS! 

For the first month I checked the battery packs twice daily (morning and evening) and everything was working well. I will say here that I used repakr to build the packs so they were for all intents and purposes all evenly matched.

After a lot of trial and error I think I have a plan packing the batteries together. I have built 7 boxes to hold 320P. This will allow me to fit everything back into the server cabinet I have on hand.

Next I need to attach busbars to which battery bank apply the covers. Once this is done it is fingers crossed the boxes will fit and the system goes back online this weekend.

The busbars are  cut and drilled! The system is back up and running. Suffice to say that it was much easier in my head that it turned out to be.

 

still need to tidy up the BMS wiring. The solar system has been running now 5 hrs powering my lights so I am as happy. Tomorrow will see how it charges up. 

Afew lessons learnt for the next build! This system I think I will leave alone to do its thing for a while. 

I like the server cabinet and i will definitely build the next battery pack to fit more space effectively in it! So now I start the hunt for 4000 odd cells to build that battery (a year plus effort unless I fall into a solid source of used batteries!)

it has been year since I posted anything about this DIY 18650 powerwall. suffice to say despite my best efforts it has killed me,  not exploded and burnt down the house, it has not caught fire and (again) burnt down the house, it has been surprising maintenance free and actually boring! so you add some spice into our relationship I decided to add a few more cells... the powerwall as of this weekend will have been official 320P 14S with any average cell capacity of 2200mAh. 

I have moved the powerwall temporarily out of the file server cabinet and onto shelving in the garage as I plan a "new" layout to accommodate all these additional cells.This setup is current 280P 14S and it is up and running thanks to ESKOM's insistence on gifting us loadshedding.

Before I am shot by all safety loving persons i will say in my defence that I have locked down the garage so the inquisitive elves in my house do not wander into the garage to investigate my toy! The powerwall should be back in the cabinet in the next two week all going well.

I will hopefully post some pictures of this monstrosity on the coming week and of the new layout out in the cabinet (if I can actually learn how to stick weld.....

Finally the last of 4 80P 14S packs is now done. I have posted a few pictures showing the individually fused cells. As done on the previously built packs I used 3Amp glass fuses soldered onto the positive side of each 18650 . The fuses come with long tails that have to be trimmed, so before soldering began I had to trim one side of each fuse to shorten it before attaching i to the 18650. The other side is then soldered onto the busbar. once I solder the fuse to the busbar I then trimmed the excess fuse tail to tidy uo the look. 

tomorrow is that day to get the 320P 14S setup in its temporary position and see out it behaves. This weekend I risk life and limb to try weld a frame together that will hold the whole pack up inside the server cabinet....