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JAP (Just Another Powerwall or Jesus Angel's Powerwall)
(11-01-2017, 12:24 PM)jesusangel Wrote: 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.

can you pls give a bit more insight about your esp approach? 

I can imagine, that you measure all packs and compare them. then you put 4.2v on under voltage packs and charge them until they are even with the rest or so...

Currently i am workung on an esp solution that measures voltage of each pack and temperature, just for controlling purposes

Hi, Yes the ESP have as default overvoltage 4.1v but have conenction to mqtt server to overide this value, and yes when that value es reached the mosfet is activated and the resistors waste some energy (4.1v/4.4Ohm=0.93Amps max. So the rest of packs can reach the max allowed voltage, currently this happening every day because I have a pack that must have some bad cell. In optimal conditions packs must reach the same voltage when charging because we use top balancing.

Appart of this I'm not very happy with this solution, ADC readings fluctuates a lot, until I disable wifi while measuring voltage. And I don't know if it is because enabling and disabling wifi that after some days it hangs. Yesterdays I change the router firmware and after this the ESP measures keep stuck and I must reboot it too. So finally I'm thinking in other solution to monitor the battery.

Maybe you have better luck, I made it with arduino IDE.

@jesusangel i'm wondering if usign Analog Digital Multiplexer like: /> will give better result. I order some... i will let you know in 1-2 months Big Grin
Korishan likes this post
Ok, i see. It is a pretty simple but effective way...

I like espeasy due to its simplicity (no programming skills needed) and it supports multiplexed adc and 16x gpio which could be easyly used to measure voltage and switch on mosfet or even control it via muxed pwm...

I like it!

Long time with nothing to tell, but tomorrow if everything goes fine will start solar production for first time. 12 SW290 panels are wating to be installed.

14 packs ready to install at wall, and cells for another 14 waiting after capacity test to check voltage after resting for some weeks.

More Pictures tomorrow.

Korishan likes this post
More than half of the work done, but only had time to install 6 panels due to few problems, untill next weekend I have 1/2 of power.
We end at 18:00 and solar radiation was low and only get 0.4kw of 1.74Kw peak.

Not too much but happy to see my first solar watt.

DK100 likes this post
Work done, I forgot to take a picture once everything is over, just one in the middle of the process.

My roof have one only inclination perfectly oriented to the east, so I use some alluminium supports at 45º, my optimal inclination is 34º, but in the south of Spain in the summer have enough radiation so better get some more Kw in the winter.

Tomorrow is the day of the batteries, I must enlarge the busbars so I can upgrade 3x my storage power and add 2 more Kwh, today I've only obtained 7Kw because of lack of storage. 

Ibiza and Korishan like this post
Litle update, almost 4 months without issues,  installed 14 active balancers and updated to 14s100p, enough to run almost all night, no more than 5 hours of air conditioner in the bedroom. So some days I had to take some watts from grid, but the invoices of the 3 months fo summer almost equals, only hired power, +-30 Kwh and taxes, 15€/month.

Winter is comming and I dind't like the way the panels was fixed to the tiles so I improved today with what we call here "winds". 

Follows general picture not included last time, and detail of improvements

120 batteries bought at ebay (I hope 5 more kWh), I think a good deal, and he has more, it can interest you, from Poland only send to Europe.
Korishan likes this post
(09-23-2018, 06:13 PM)jesusangel Wrote:

Have to login before we can view the page Huh
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Certified 18650 Cell Reclamation Technician

Please come join in general chit-chat and randomness at Discord Chat (channels: general, 3d-printing, linux&coding, 18650, humor, ...)
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(09-23-2018, 06:16 PM)Korishan Wrote:
(09-23-2018, 06:13 PM)jesusangel Wrote:

Have to login before we can view the page  Huh

Fixed, sorry I pasted my summary of orders instead of seller's list of products
Korishan likes this post

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