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JAP (Just Another Powerwall or Jesus Angel's Powerwall)
(08-16-2017, 09:01 PM)jesusangel Wrote:
(08-16-2017, 08:21 PM)owitte Wrote: yes, your packs look a little 'fragile'... I guess the weight is like mine, around 1kg per pack. You should not underestimate that. I fixed my terminals with zip ties, too, and most of them broke overe time, because I zipped them with too much tension. If you make them a little loose, they will hold the weight of the pack and you'll still be able to adjust the terminals on the bus bar bolts. If you want, I can show you detailed pictures of how I did it.

Have sun!

Of course Oliver, any tip will help, today I've made the busbars and tomorrow I will screw them to the wall and make the electrical installation waiting for the inverter that yesterday left Germany by dhl not dhl express so I supose tomorrow it will not be here as ebay said when I bought it.

Today I've bought too a bag of zip ties.

OK, I added some more pics of the building process of my packs in my thread, see here (also don't want to mix up pictures here). If you have any questions, feel free to ask Smile .

Cells tested: 6.072 (overall: 12.021 Ah, average: 1.980 mAh)
Cells in production: 2.940 (overall: 6.174 Ah, average: 2.100 mAh)
Wall bank: 7s420p, 882 Ah, 21 kWh
Project page
Live solar/powerwall values
Daily graph
Installed and charging, load not connected yet. Very ugly installation, first pack busbars a litle irregulars.

Finally I decided to change the setup to 7 serie tall so the busbar bellow was double side and only have 15 busbars for 14 packs, now I need 16 that is because I have 13 packs only.

Korishan likes this post
don't get it, you want to build a 14s powerwall with 13 parallel packs...?

and why you don't want to use the whole height of your wall? The 1st pic you posted looked good, 15 bus bars for 14 packs seemed to fit... with 2 x 7, you'll need one bar more and the space will only be good for half much packs... or did I miss something?

Cells tested: 6.072 (overall: 12.021 Ah, average: 1.980 mAh)
Cells in production: 2.940 (overall: 6.174 Ah, average: 2.100 mAh)
Wall bank: 7s420p, 882 Ah, 21 kWh
Project page
Live solar/powerwall values
Daily graph
I got the cooper pipe at work and this two weeks I'm on vacations, as you can see the holes at wall are done at the top right, just waiting the 16th pipe, the pack, and reconfigure the voltages.

This wall is of my garage (you can see to top of my car in the first picture) so while measuring real needs of height (18cm*14 = 252) I decided to get only the half of the wall to not install packs too close to the car or the grounding connection box you can already see at the botton of the picture or close to the roof , I usually touch the wall with the car while parking and cables installation goes close to the roof (notice the connections box used to connect to the main).

Now I have place for 28 more packs with the current pipes, when I need to expand just have to move the pipes a couple of centimeters, screw them to make a double size busbar and install new ones at the left.
Litle Update, working on BMS side.

ESP8266 with resistor divider to adjust 4.2v to 1v range, N-Mosfet and 2 x 0.820 Ohm in serie.

I will replace the DC-DC converter you see in picture with TP4056 with 5v out. So final cost of the balancer is 3€.


Configured data send to Graphana server and MQTT server that by now is in one internet server but in future will be a Raspberry Pi in same lan, so with MQQT can get alarms (as you see in console screen) and cut charge or discharge on alarms. 

In grafana and console you can see discharging until 19:00 when MPI 4K have programmed to start charging (off-Peak) then esp8266 starts to activate and deactivate the mosfet, with 1.6 Ohm at 4.2v makes a load of 2.6 amps, that, for a pack of 20Ah, makes decrease the voltage suddenly, in next loop the mosfet is deactivated and so on, with more packs or greater resistor this won't happens and discharged will be more sustained. Finally charge stops at +-21:00 and voltage stabilizes.


Now after 2 weeks of holidays I already have more cells holders from friend and I can build next 14 packs with 2KWh. Ordered too ESP8266 and TP4056 boards. I think enough work for next weeks. 

See you
cmg_george and owitte like this post
Those ESP8266 really are cheap... interesting ... going to follow Smile
18x 300Wp solar off grid and 10x 180Wp solar tracker grid-tie
10KW 3phase hybrid inverter. 40Kwh 18650 storage (for now)
My setup:
(08-28-2017, 06:58 PM)wim Wrote: Those ESP8266 really are cheap... interesting ... going to follow Smile
Yes I used for this test an old ESP12F  that makes all a litle dificult because of using DC-DC adapter from 8.4V to 3.3V, (2 packs for power it just 1 pack to measure and discharge) and soldering TTL to USB cable, I have ordered Lua NodeMcu that have usb converter and voltage regulator for 2.26€ each just need TP4056 for 0.26€, mosfet, resistors and some cable and a box to isolate a make it less ugly, so finally I think less than 4€.
owitte likes this post
yeah, I hate to solder these guys to a 2.5mm adaptor board. I now use the nodeMCU development pcb, includes everything you need, incl. power supply and USB-TTL adaptor. Much easier to handle Shy .

btw, nice busbars Big Grin .

Cells tested: 6.072 (overall: 12.021 Ah, average: 1.980 mAh)
Cells in production: 2.940 (overall: 6.174 Ah, average: 2.100 mAh)
Wall bank: 7s420p, 882 Ah, 21 kWh
Project page
Live solar/powerwall values
Daily graph
Finally I got my 14 single cell BMS with ESP8266, it is working for more than a month, but I finished to refurbish them last week, because of too low Ohm resistor and thin cable used that makes a high voltage's drop,  almost 0.1V, when the resistor was active (I have got only 40P packs with +- 70Ah). So this is my current setup

1- ESP8266 Nodemcu 2,24€
1- FQP13N06L N Channel Mosfet 0,57€
2- 2.2Ohm 10W resistor in serie 0,49€
1- 0.9V-5V to 5V DC-DC Converter. 0,98€
1- Switch 0,31€
1- Plastic Box  0,72€
1- Pin Header 0,15€
1- Proto Board 0,34€
2- Connectors 0,23€

Total cost, 6,03 € per BMS + cables, solder and a lot of time. 

The only problem I have now is that sometimes the ESP8266 hangs, don't know if it is the quality of board, the sketch made with Arduino IDE, or what, that's because I include the switch, I have got an ESP-12E since a couple of years to open my garage door and haven't any issue until now.

I already have tested cells for another 14 20P packs, this time with standad cell holders and XT30 connector (I will made it with flexible cable), so will need to double the wall bus bars. That is work for a couple of months . I still haven't any solar panel that's because you see a perfect discharge/charge graph every day.

In picture 1 you can see the effect of doubling the resistor, picture 2 balancing of yellow pack after 4 days, next pictures my BMS.

Hi @jesusangel, how is the balancer working?
Still having problem with ESP hang?

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