Welcome to the forum. I can give you some basic info, do
check out the FAQ section (clickable link) where
@Korishan did a huge job in organizing the knowledge base.
For testing the cells your basic tools are surely:
- A
decent DMM with a certain degree of accuracy/precision, a basic one can be found on AliExpress (my fav for many things!) for around 10/15$. You want to check voltages, continuity in wires when working with your 18650 cells.
- An
IR Tester, I bought the cheapest YR-1030 and I'm very happy with it. For each cell you'll want to know the Internal Resistance and compare it to the datasheet. The older / more used cells will have a higher IR, over a certain limit the cell may be considered "too much used". Over 75mOhm my cells degrade very quick, year after year, so I consider them 2nd grade, which means I'd use them for leds, lights, low current powerbanks, but not for high-current applications. You can search datasheets in the
Cell Data & Specifications forum.
-
A 18650 charger, choices to begin with are LiitoKala 500S (4 cells) or, even better, a nice Opus device. I got myself the cheaper LiitoKalas (In 3 years I bought 3 of them for around 15$ each). You'll use these to determine the cell's capacity by doing a full C-D-C cycle (charge/discharge/charge) cycle, called NOR test on the Liitokala.
A decent
soldering iron. I used my 15$ cheap 60W iron for years, then I bought a nice 150W big iron on Ebay. What's important is to buy good quality tin/solder, avoid AliExpress for that because their tin is usually very impure. I buy german tin on Ebay.
Youll probably start wanting to solder more cells together, in series and/or in parallel to increase Voltage (in series) or Capacity (in parallel). So there you'll probably start looking for enclosure boxes and BMS boards (mandatory), and eventually decide to try
spot-welding and
nickel strips. Again, for my low budget lab
for my Birthday I got myself a Sunkko709AD, I love it, around 180$ on Aliexpress, shipped from the EU to Italy (no extra taxes). It's not the most professional device but it's solid, you can do thousands of solder points in a session, only rest it for 5 minutes when it starts to get very hot. Avoid the 10-20$ tiny spot-welding units, they simply can't do the job.
What's important for you, in every moment keep in mind
security. So your first in-depth researches must go in that direction. High-temperatures, fire, water, short-circuits,
personal security devices (gloves, glasses, etc) and electrical security devices must be your first concern. Please do ask! What I found out after my first months of welding was to protect my eyes, after getting tiny solder balls (TWICE!) in my eye!
That's my DIY concept, perfectly in line with Second Life Storage
