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New to harvesting
#1
hi all.

I am new to harvesting cells.
Are there any good places to start ?

I understand the basics but I'm looking to further my knowledge to start building a power wall safely and want to learn how I should be charging and testing cells properly so I dont kill them.

I have been keeping a distant eye on a diy powerwall group on Facebook and picked up 4 shoto sda 10-4850 units free that I would like to test the batteries in them and hopefully bring a few of them back to life to use.

They have a lithium pouch cells but I haven't even started to strip them to see the details. They all have there own bms but the person I got these from killed a bms when they opened it.

Any help would be great.
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#2
The Opus BT-C3100 is a great place to start for testing the cells. Set it to the "Charge Test" function and select 1000mA current. It will charge the cells fully, discharge them and report the stored capacity, then charge them back up to full again. After capacity testing, leave them sit for a few weeks and re-check the voltage. If any of them dropped substantially, such as below 4.10V, they're self-discharging at a high rate and should be recycled.
CHEAP! 2200mAh Sanyo Cells for Salvage, Only $0.17/ea!!
^ Use discount code "BATTERY" for 10% off!
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#3
Welcome. You are in the right place.

If you don't mind me asking, but do you have any past experience with lithium batteries? Perhaps with RC toys that might accelerate the learning process.

A good place to start is to by learning the fundamentals about lithium battery and saftey first. Also to obtain the right tools to provide support during the process.

This includes:
Gloves / PPE, reliable multimeter, soldering station, cell chargers / tester, cutters / hand tools...

Its also good to know what your build goals are, or if you are just a general tinker that is playing around that is fine too!
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#4
Thanks for the reply.

My background is in the automotive industry where I have done a fair bit of electrical wiring work mostly installing car audio. Also since I was fairly young I have been tinkering with computers. so I would say i have a bit of experience with electrical already but keen to learn more.

Im looking to move towards building battery storage for my house. I am in Australia and I have solar on my house which in this country can be useless unless you can store the power to use later.

I already have a small arsenal of tools at my disposal but I'm looking to get the right equipment so I can give this a crack. As I'm hoping that between the 4 units I can get 3 of them back up and running to start towards powering my house.
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#5
Great, and good to know.

I can understand the eagerness to want to hit the ground running, and you will likely spend a ton of time processing cells and learning as you pass that time.  If I can give you one piece of advice is don’t rush the process, grow it organically and at your own comfort level.  Don’t expect you will get it right the first time either, especially if you don’t make the investment in both time and equipment.

I say this more from the standpoint of safety and long term performance.  It is important to note that stuff is dangerous, and doing it on a larger scale only compounds the risk.  Poor process and procedure in testing is going to lead to quality problems, downtime, additional time and maintenance cost.  To be honest these things actually need to be looked after.

This is already a respectable undertaking even with brand new batteries.  To make matters more challenging, we are building with recycled cells of unknown quality. 

I highly recommend building a proof of concept first.  Could be a test bench setup, could be a portable battery pack, or even an RC car to get you more familiar with the general charging/balancing/discharging/storage-maintenance practices. 

I love RC equipment so much in this hobby because its literally identical in practice, and my past experience with it REALLY help set the foundational groundwork for these types of projects.  I highly recommend you get a good one as it is the Swiss army knife of battery work; it will become such a valuable tool (pack maintenance, capacity testing, charging, balancing, discharging, internal resistance testing, and a lot more)  It’s a great tool to validate the results from your bulk testing gear. 

There are so many ways to accomplish this that you might change your ideas/design depending on what you learn.  I feel like my project never really finish, they just evolve. 

Either way, hope that wasn’t too much all in one go.  Go crack into some packs and start collecting cells, but don’t be in a rush to actually slap it all together and get it into production.

Also, you mentioned you already have solar?  Is this a professionally installed grid tie system?  The charger/inverter combo, panel voltage, and other things are all going to be important in system design and equipment selection.  And don’t forget to research BMS system like Batrium or many of the other DIY systems people have created.  There really is no set standard to how this is done…

For a proof of concept type build, I made a little battery board as a BMS testing bench, but it could also serve as a learning tool.  The 2nd part ill actually be using it to test BMS boards.



Here is some of the chargers and gear I like.  Obviously find whatever works for your budget.  Plenty of options from $20 and up.



You are going to have plenty of "B Grade" or "C Grade" cells that might not make it into your powerwall.  You can always make a smaller project and practice soldering, spot welding, PCB, or whatever route you decide to go before jumping off the deep end.



Don't forget that EV cells are for the most part a larger 18650's.  If you can gain access to those, then its another very valid way of building.  I have some EV car cells that I plan to use myself.  This is where the RC chargers really shine as they have better power handling and can better process "modules"



Hope that wasn't too much all in one go.  Enjoy, have fun, and stay safe.
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#6
Yeah this is why I'm keen to start with these units I have just slowly process the pouch cells and see what needs replacing to get a premade system back up and running to show proof of concept to my partner.

Honestly when it comes to the main house system I need to change my inverters and id like to go to leaf battery setups to power my house.

But thanks for the videos ill crack in to them over the weekend
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#7
Do I need to be charging all the cells on there own?

The units I am recycling have 3p cell setup can I charge them all together will it work like that or do I need to desolder them and do them all on there own.

Is it possible to test the unit complete. So as these units have a bms can I use a power source and charge it up to the full spec leave the unit sit then open and test what cells are looking voltage or will it trickle the other cells to keep it balanced.
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#8
You really should charge each cell individually if possible, it only takes one bad cell to make a battery pack itself considered bad. When you think about it, if one cell is a vamp cell, it will drain whatever power it can from all others connected to it in parallel.
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#9
How old are they? Paralell cells AGE pretty darn Close and can be tested as such. Its just that in most cases its easier to dissassemble Them because of the form factor

Series cells must Always be dissassembled!!
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#10
Parallel testing should not be done, no advantages except a little extra time gained.
The actual testing time is nearly the same as if you would test them separately since you still have to fully charge and discharge them for a relevant test.

If you have 3 parallels and they are in good shape, a testing could end up good and should not be much difference between cells, but in the case of one bad or average cell, the whole pack will obtain a lower result even with 2 perfectly good cells. If you have a pack with 3 average-shape cells you may get the same result as one with a bad cell and 2 good, or other such variations.
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