JAP (Just Another Powerwall or Jesus Angel's Powerwall)

[owitte]

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 youdetailed pictures of how I did it.

Have sun!
Oliver

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, seehere (also don't want to mix up pictures here). If you have any questions, feel free to ask .

 

[jesusangel]

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.

 

[owitte]

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?

 

[jesusangel]

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.

 

[jesusangel]

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 MQQTcan 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 ofholidays I already have more cells holders from friend and I can build next 14 packs with 2KWh. Ordered too ESP8266 and TP4056boards. I think enough work for next weeks.

See you

 

[wim]

Those ESP8266 really are cheap... interesting ... going to follow

 

[jesusangel]

Those ESP8266 really are cheap... interesting ... going to follow

Yes I used for this test an oldESP12F that makes all a litle dificult because of using DC-DC adapter from 8.4V to 3.3V, (2packs for power itjust 1 pack to measure and discharge) and soldering TTL to USB cable, I have orderedLua NodeMcu that have usb converter and voltage regulator for 2.26 eachjust 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]

yeah, I hate to solder these guys to a 2.5mm adaptor board. I now use thenodeMCU development pcb, includes everything you need, incl. power supply and USB-TTL adaptor. Much easier to handle :shy: .

btw, nice busbars .

 

[jesusangel]

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- PlasticBox 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.

 

[cmg_george]

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

 

[jesusangel]

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

Yes, not very often, maybe one balancer per week or less, but some time when it hangs the mosfet keep activated and if I don't reset it it unbalances this pack, I have grafana alerts on Telegram so I have a message if a balancer stop sending data or goes out of UV or OV limits so not a big problem.

 

[Klommer]

Hey there,

as im looking for an idea of an bms i like the ESP-version you build up.

Why dont you integrate a external watchdog to the esp? You could simply add it to one of the left ios and if the WDT doenst see the timer comming it will toggle the reset pin. Many different things available in SOT-23 or SO8 like these folks here

http://www.ti.com/lit/an/slva039/slva039.pdf

Some of them are also available with programmingresistor for the wdt-period


regards

Carsten

---

After i read the fully thread i would like to give the advice that the ESP8266 is taking at me (As a Node-MCU in Openhab Smart-Home) 80mA @5V. So thats 1,92Ah over a day. And thats without all the losses in boost-converter, voltage divider etc.

If you will achieve your pack with your 800 cells @ 2Ah with 14s youll get ~ 115Ah per block. That means youll get 1,7% discharge by the ESP per day...

 

[jesusangel]

Hey there,

as im looking for an idea of an bms i like the ESP-version you build up.

Why dont you integrate a external watchdog to the esp? You could simply add it to one of the left ios and if the WDT doenst see the timer comming it will toggle the reset pin. Many different things available in SOT-23 or SO8 like these folks here

http://www.ti.com/lit/an/slva039/slva039.pdf

Some of them are also available with programmingresistor for the wdt-period


regards

Carsten

---

After i read the fully thread i would like to give the advice that the ESP8266 is taking at me (As a Node-MCU in Openhab Smart-Home) 80mA @5V. So thats 1,92Ah over a day. And thats without all the losses in boost-converter, voltage divider etc.

If you will achieve your pack with your 800 cells @ 2Ah with 14s youll get ~ 115Ah per block. That means youll get 1,7% discharge by the ESP per day...

---

Yes even a 555 would solve the problem but I won't unmount the 14 balancers and redo them. I already made it once. The 14 ESP consume 134 watts every day, 0.4w ESP/hour. The MPP Solar Inverter comsumes 200 time more, more than 80w/h, not very optimized hardware in both cases, you must dedicate a couple of panels only to feed the whole system.

Regards

 

[Klommer]

y thats right, the perfect system was not made at all...

 

[jesusangel]

Building next 14 Packs, this time with XT60 connectors and some fexible cable.

I've made my packs with very basic tools, so even a simple hole is not at the right position, or the twisted busbars have measurement differences. To mitigate the problems that this causes I will connect with flexible cable and hang the packs from the wall busbars in other way, a couple of hooks or similar.






No much time recently so will take some time.

Regards

 

[daromer]

I can see some issues on that pack. Your fuses are crossing each other and even the legs are. Thats not very good. They should all be firmly and nicely attached with no contact

 

[jesusangel]

Not a good picture, no fuse makes contact with other in the inner side. So there is only a path from positive side of every cell to the fusible part of one single fuse, from that part to the busbars yes some can be making contact with others and finally even 4 are solder in same place of the busbar.

 

[Korishan]

You should shorten the legs on the fuses. Even if the legs are 2mm long, that's long enough to make contact

 

[jesusangel]

Picture updated

 

[daromer]

You should rearrange them somewhat. The rings show where i meant its way to close. No need to keep them tangled like that. Its just extra work the day you need to work with it.

Cut off the legs and put them all in same direction kind of and it will work.