LabBench grew to 9 tools, and I shipped a second product

A few weeks ago I turned four free browser-based engineering demos into LabBench — a suite people could actually use, not just look at. This week it grew again, and I also launched something completely separate. Two new LabBench tools (7 → 9) EV Battery Management Simulator — a 4-cell pack model with real coulomb-counted state of charge, an OCV + IR-drop voltage curve, a lumped thermal model that trips a simulated BMS above 70°C, and passive cell balancing you can actually watch converge over time. Smart Energy Meter Dashboard — toggle household appliances and watch real vs. apparent power, power factor, a source-impedance voltage sag model, breaker-trip current logic, and live kWh billing, all computed from scratch. Both reuse the same Supabase-auth + Pro-gated save/load pattern as the rest of the suite. Try them: https://labbench-hub.vercel.app/ A second, separate product: PrepBench Not ECE this time — general aptitude-exam prep (Percentage, Profit & Loss, Time & Work, Speed-Distance-Time, Number System, Probability, Squares & Cubes, Geometry, Data Interpretation). Free interactive reference + practice drills with instant feedback and a live streak/accuracy tracker, no sign-up needed, plus a paid cheat-sheet PDF bundle. Try it: https://prepbench.vercel.app/ Both are open source under a source-available license — code's on GitHub if you want to see how any of it works: https://github.com/Dhananjay-ku-seth Feedback welcome, especially on the battery thermal model — first time modeling BMS behavior client-side.