My last battery-related entry was on TW560 getting a new battery pack.
(Finally, I have the time to write an entry after my epic 10-day TWIKE adventure across some of the highest passes of Europe with less charging stops. 🙂 )
This entry is dedicated to the previous’ pack’s second life as a stationary battery pack for a Swiss household.
The application they are going to be used in is very simple: Solar panel – charging circuit – battery – inverter – 230V-loads in household… grid. The idea is to keep renewable energy in-house and only send energy to the grid when all other options are exhausted. (The concept is simple enough that even Tesla themselves have entered this market 🙂 ) More on how this concept works in real life a little later.
The old pack consists of 5 larger blocks, weighing about 95 kg in total. Minutes after the blocks are extracted from TW560 to make place for their successors, Ralph rolls them into their 2nd-life production facilities.
All blocks have to be re-configured to fit new voltage requirements. In order to do so, the blocks which have been designed with re-usability and single-cell accessibility in mind have to be opened and re-usable cells are extracted.
I cannot stress this point enough: When purchasing a battery pack, if you can, ask your battery provider what will happen to your pack when it reaches its end-of-life as a traction battery and what it will take to re-use the batteries! You might be surprised!
(This is, again, one of the reasons why I chose dreifels’ pack over any other option 6 years ago!)
A few screws later, the first cover comes off and Jane can start removing the connectors linking individual cells.
TW560’s battery bay, in the past, had some issues with water/salt entering due to structural issues following to an (unforgettable) adventure crossing India in a TWIKE.
This is why every cell undergoes a visual check first. 240 of them made up TW560’s previous pack.
Some of the cells definitely show signs of abuse due to unusual operating environments!
Copper rust & traces of DC discharges towards the pack enclosure. (which lead to this problem)
Dust & small debris from our many adventures entered the pack and started to work its way into the cell cover.
No comment 🙂
Of 240 cells, 6 cells were beyond repair – part of them leaking electrolyte.
7 new packs @ 32 cells were created – the 10 remaining cells are used as backup.
As a last step, the packs are placed into an enclosure: Voilà , ready for deployment.
So, what’s going to happen with these new blocks? They are going to be placed into a “powerwall” of sorts. dreifels’ turn-key product.
Let’s have a look how the enclosure looks like from the inside, shall we?
No batteries yet, however, some of the controllers are present already.
Nowadays, it is important to offer complete access to all data, current and historical via the internet. The antenna and GPRS module offer this functionality. dreifels constantly monitors battery pack health and usage and changes parameters when required – prolonging battery life where possible.
After installing TW560’s former battery packs plus a few additional packs, this dreifels PowerCabinet will provide a total of 20kWh at a peak of 10kW on three phases.
Prior to any use, every single pack is charged and balanced by dreifels – I get an email letting me know that my regular balancing and general taking care of the packs is definitely showing with the batteries coming from my pack. (i.e. perfectly balanced cells!)
Then, finally, it’s time to fire up the whole system for real.
After starting up the inverter, a first set of information is shown on the display – solar power on the panels vs. energy consumed, delta required from the batteries.
For any self-respecting dreifels ‘PWRcabinet’ (better marketing name req’d) user, living fully off the grid is the goal – read about a dreifels customer testing his dreifels-System (in German).
First tests are promising – a smaller system supporting a ‘normal’ household is 100% grid-negative – this household won’t draw any energy from the grid, ever!
If you own a Tesla and want to use this product, you might want to consider buying a product with more than 20kWh 🙂 (which is absolutely possible, since there is no limit on installed pack size.)
The power of the sun is evident in this example – the pack is fully charged by midday. Any additional energy is ‘lost’ to the grid and cannot be used by the electric car charging throughout the night.
If you want to know more about this solution, click here.
If you want to support me getting TW560’s batteries installed at my 100 year old home – get in touch 🙂