Here's what I've been up to since last update:
I decided to buy unused old stock samsung 29E to reach the 80p which means I'll have ~10kwh powerwall.
These cells costed me ~0.80 EUR/cell, so that gives ~75 EUR /1kwh, that's quite good considering it's cells with original capacity.
My laptop processing results are 40% good cells, which at around 1EUR per laptop pack gives ~37EUR/1kwh.
So basically I come to the conclusion that paying 2x more per 1kwh is worth since the laptop batteries are of unknown state-of-life, and these are theoretically new, and don't have to spend time opening the laptop packs.
I have at the moment ~5kwh from laptop cells, and 5kwh from unused old stock, which means that total cost of cells for my
10kwh is ~600 EUR.
That's quite good I think. Let's see how long they last, hoping for at least 5 years if I treat them nicely.
So moving forward with this I soldered all the cells:
prepared the bus bars:
had to buy a torch to solder the lugs:
I'm quite happy with the end result:
Then I started building some kind of holders to keep the packs in the wall.
I kind of followed Pete's design,but did itwith just wood andaluminium, so it's kind of DIY of the DIY
It's an incredible feeling to see all the 14 packs up in the wall.
When I started this endeavour a year ago and open up my first laptop packI didn't dream that I would come this far, I was thinking maybe a 1kwh powerpack of some kind for charging small electronics, but a house powerwall seemed to me like something out of my reach. Thanks to all youtube videos of Pete's/Daniel's/Joe's and others, and with the help of the forum, I slowly become confident it will be possible even for me to do it
This DIY community is awesome!
I bought a ABB shunt trip, the same as Wim and Danielso I'm hoping it will work nicely with Batrium's Watchmon (or at least Daniel will come up with a way to make it work nice, I'm counting on him
).
So the current state is that I'm soldering the glass fuses:
I'm using the 1.5amp version, hoping that voltage drop at small loads per cell will not be relevant.
Still have to connect the longmons.
In next few weeks I'll have them ready to connect them up to the PIP.
I'm thinking to test each packs capacity to try and make sure they're within very close capacity to each other, but testing something like 200ah packs with an icharger 5amp discharge will take almost 2 days per pack, and I don't know if even my icharger 106b will be able to measure/show above 99,999mah.
Otherwise I'll just connect them to Batrium and see if they are somewhat close enough that will not cause to much bypass at top.
Feeling quite excited because I start to see the light at the end of tunnel, after so many hours of working on this.
Also thinking about purchase another 3 solar panels to have at least 1.5kWp. Maybe even more if winter sun hours are not enoughto charge 10kwh powerwall given 2 days of sunnywinterweather.
I'm also impatiently waiting for Daniel's new soft for the Batrium/MPP, since I want to controll PIP AC charging from raspberry ( will probably need to use custom firmware fromhttp://forums.aeva.asn.au/).
Basically I want to charge a bit the powerwall (if SOC it low)during nightly cheap tariff IF weather forecast for next day doesn't predict too much sun hours.
This way I hope to never again have to pay peak tariff from grid even when a few winter days without sun.
Also I tested emoncms for calculating KWH from power samples, and given they're 10seconds it's a bit off compared to SDM120 kwh.
So I'm thinking still on how to precisely calculate kwh for a few things: 1) PCM solar charging 2) battery IN/OUT.
Daniel says that with influx queries some kind of value is possible, but not the best way. I'll look into that.
And also the new shunt from batrium maybe it will be able to calculate kwh besides the ah for daily charge/discharge.
That used in conjunction with the SDM120 meters, would allow to have daily kWh values available for all of these: