Battery Testers

The "is this used 18650 worth keeping?" instrument family. A cell tester charges and discharges a battery on a known profile, measures real-world capacity (mAh / Wh), and (on the better ones) internal resistance. Pair with Electronic Loads for higher-power pack work, Multimeters for spot voltage/current checks, and USB Power Testers for USB-output power-bank testing. For salvaging cells from packs see Soldering Stations (you'll spot-weld, not solder, when assembling cells).

Slot-style 18650 / Li-ion cell testers

• ★ Litokala Lii-500 / Lii-600 / Lii-PD4 — the hobbyist standard. 4 independent slots, capacity test, fast charge, internal resistance (Lii-600 and PD4 have IR mode). ~$50–$80. The default "first cell tester."
• Opus BT-C3100 v2.2 / BT-C2400 — the perennial alternative to Litokala. 4 slots, same feature set, slightly more accurate by community measurement.
• Vapcell S4 Plus / YR-04 — newer hobby tier; some models do active cooling on slots, useful for high-rate cells.
• Xtar VC4S / VC8 / Dragon VP4 Plus — primarily chargers but with capacity-test mode; OK for non-precision use.
• Nitecore D4 / UMS4 — OK chargers; capacity test is approximate.

Pack / high-power testers

• ★ ZKE Tech EBC-A20 / EBC-A40L / EBD-A20H — see Electronic Loads. Up to 40 A discharge, full charge cycle, USB logging. The hobbyist pack-tester standard. ~$150–$400. Closed Windows software (EBTester) plus FOSS Python libs.
• Tomometer / TBC battery loads — Chinese marketplace e-bike battery testers; YMMV.
• Foxwell BT-705 / Ancel BST-200 — automotive battery testers; CCA/SOH for car batteries, not lab-grade.
• Hioki BT-3554 / 3563 — premium battery internal-resistance meters; lab-grade, expensive.
• GW Instek GBM-3300 — bench battery analyzer; serious money.

E-bike / EV pack testing

• For EV / e-bike packs (>50 V, >10 A), bench battery testers are insufficient — you need a bench-grade DC load (Itech IT8500/8800, Chroma 6310x) and a high-current PSU. See Electronic Loads and Power Supplies.
• Pack-level BMS testers (Daly / JBD / EngSpec) — for verifying smart BMS behavior; usually USB-paired with the pack's own BMS.

Internal-resistance specifics

• YR1030 / YR1035+ — pocket 4-wire IR meters; ~$80–$130. The hobbyist-favorite handheld IR meter. Important: 18650 IR depends on SoC, frequency, and temperature; spec your test method or your numbers don't compare.
• Hioki BT-3554 — premium 4-wire AC IR meter; the lab reference.

Software / data

• EBTester (ZKE Tech) — official Windows logger for EBC-A* loads. Closed. Bluetooth/serial protocol.
• Litokala / Opus — display only, no PC export. Take a picture or write the number down.
• OpenBatteryTest / repacker / cellsorter community Python tools — for batch-processing salvaged cells; FOSS, niche.
• IR / capacity vs. cycle plotting — typically done in Python after CSV export from EBC-A* / Litokala photos.

What to actually measure

• Capacity (mAh / Wh) at a defined discharge rate (commonly 0.5 A or 1 A for 18650).
• Internal resistance at a defined SoC (commonly 50% or "after rest at full charge").
• Self-discharge (rest the cell for 24–72 h after charge, measure voltage drop). Most testers don't automate this; it's a "set up four cells, come back later" workflow.
• Cycle life is rarely measured at home — too slow, too hot — but for a single salvaged cell, capacity + IR + self-discharge tells you 90% of what you need.

License / pricing notes

• Litokala / Opus / Vapcell chargers have closed firmware; protocols are mostly undocumented. Take readings off the screen.
• ZKE EBC-A has a documented USB protocol; FOSS Python libs on GitHub.
• YR1030 / YR1035+ are closed; no PC interface.
• Hioki / GW Instek speak SCPI / proprietary protocols.
• Cell safety: any 18650 tester can fail; never run a battery test unattended in a flammable environment. Use a LiPo-safe bag or metal box.

Pick this if…

• First cell tester, $60: Litokala Lii-500 or Opus BT-C3100.
• Better IR + cooling for high-rate cells: Vapcell S4 Plus or Litokala Lii-600.
• Pack discharge tests up to 40 A: ZKE EBC-A40L.
• Pocket IR meter: YR1035+.
• Lab-grade IR / capacity: Hioki BT-3554 or Keithley 2461 SMU + Python.
• Salvaging hundreds of 18650s from packs: four Litokalas + spreadsheet workflow + LiPo-safe bag.
• EV / e-bike pack: see Electronic Loads; a cell tester is the wrong tool.