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JAP (Just Another Powerwall or Jesus Angel's Powerwall)
#11
(08-03-2017, 04:26 PM)jesusangel Wrote: So, if we need the same GND to Gate (esp32)  and Drain, we need at least all outputs to be pwm so we can send less voltage to mosfet connected to high series, there are bigger resistors too so can manage more  watts, but at these point I wonder if wouldn't  be easiest use relay boards, they are optoisolated  and only have to worry about the resistor connected to NO and send a high or low to port and you get a fix current drain.

I have been sniffing around for designs.

For me, I'm going with  something like this.  An ESP per battery pack.  The circuit provides a 1.2W dump, and voltage sensor.  If I want to add temp ill go with a Dallas 1-wire and which can be hooked directly to the MCU with a 4.7k pull up.  



To your question a relay board Yes and have seen this been done that way, or go with a opto isolated FET.

Cheers
cmg_george and goodnowm like this post
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#12
Never tested but I've readed maximum adc voltage for ESP8266 is 1v, so that voltage divider with R3 4 and R2 10 at cell max of 4.2V put 3V max at ADC pin. Zener is ok for 3v3 max too, ESP8266 have internal protection to overvoltgage until 5.8V, but over a 1V you will get 1024 readings.

About BSS308PE it is P channel and makes me wonder if the design was wrong, but found this:

https://www.baldengineer.com/p-channel-m...tages.html

and when is better use a P channel instead of N channel, good point.
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#13
(08-04-2017, 03:22 PM)jesusangel Wrote: Never tested but I've readed maximum adc voltage for ESP8266 is 1v, so that voltage divider with R3 4 and  R2 10 at cell max of 4.2V put 3V max at ADC pin. Zener is ok for 3v3 max too, ESP8266 have internal protection to overvoltgage until 5.8V, but over a 1V you will get 1024 readings.

About BSS308PE it is P channel and makes me wonder if the design was wrong, but found this:

https://www.baldengineer.com/p-channel-m...tages.html

and when is better use a P channel instead of N channel, good point.

Thanks for that, I'll redo the divider. Will also add a LED.
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#14
As we use to say here I started the house by the roof so I already ordered the inverter 

MPP Solar MPI Hybrid 4k

http://www.ebay.es/itm/4000w-Hybrid-sola...2749.l2649

Delivery date is next thursday  07/18, supposedly sent from Germany to Spain. 

Next question is the place, I will install it at garage that is the basement of my house and has a 8 meters wall and a good place for the inverter at the end of a little stairs. I'm building my powerwall like Oliver

http://secondlifestorage.com/t-There-s-a...any?page=1

I hope next few days have first 14s finished and wall busbars installed.

That's how I plan to do it.



About solar panels, I think the next summer or maybe before if I'm bored (I want to build bms, and graphana server before and keep collecting cells ) meanwhile I've moved to time discrimination rate with my energy provider and decreased the power to 2.2Kw. My plans is to charge at night with cheap rate and feed part of the house at day, I will move more parts of the house to the inverter when I had more storage capacity. By now only have 5 KWh of procesed cells and 1.5 kw packed.

 Stay tuned for more updates  Big Grin
owitte likes this post
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#15
First  1.5 KWh finished, tomorrow wall bus bars, inverter already traveling



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#16
On your packs where the wire curves over the edges and joined and soldered in the copper pipe, maybe you could take a zip tie and strap that last bend to the pack. This would give extra strength right there and help keep from stressing the fuse wires when you're connecting/moving the packs.

Nice setup, though! Smile
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#17
Thank you Korishan

Yes, zip tie will help, my pack will be connected vertically with negative bus bar down, so most the weight will be on that side that it is very strong, positive bus bar will give some flexibility and will make it easy to screw, somes fuses already broken while handling.

In last packs I've changed from 2 AWG 10 (6mm2) twisted cables to only 1, for a maximum of 20 amps per pack (10 per cable) is enough and easiest to turn, solder, etc
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#18
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!
Oliver

Cells tested: 5536 (overall: 10854 Ah, average: 1960 mAh)
Cells in production: 2940 (overall: 6174 Ah, average: 2100 mAh)
Wall bank: 7s320p, 672 Ah, 16 kWh
Box bank: 7s100p, 210 Ah, 5 kWh
Project page
Live solar/powerwall values
Daily graph
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#19
(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!
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.
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#20
I love that you are making 20p packs. I am also. It seems the smaller packs are not very common. I like that I can add as many parallel packs to the initial 14. So I can make a second string of 14s20p or 14s80p or whatever I want. I just wanted small packs for ease of handling and a lot less re soldering if I have a bad cell and need to rebuild a pack. And I'm poor! A smaller first string is more manageable within my budget. My accountant (read wife) is very keen to get a return on investment! Lol!

Thank you for sharing! Please keep updating. I love how this community is so open and freely giving of good advice.
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