Private betarequest access ↗

Find the hot cell before it finds you.

Browser-native pack design with real electrical and thermal simulation.

Open the editor →See an example pack ↗
A hex cluster of seven 21700 cells viewed at a 3/4 angle, with the central cell glowing warm amber and dramatic side-lighting casting long shadows across warm paper.

P-group·7 × 21700·sim 0.34 s·peak 62 °C @ 8 m

Real electrical simulation

MNA solver for voltage, current, and resistance, the whole loop, end to end.

Lumped thermal modeling

Heat flow, hotspots, and cooling under your actual load profile.

Runs in your browser

No install, no licence. Open the editor and design.

Inside the editor

Cells in 3D. Strips on both faces.

Hex-snap placement, top-and-bottom-face nickel routing, fold lines, series groups, all addressable in 3D, all in the browser.

The battery-builder editor with a 3S7P pack: 21 cells in three series groups, 20 nickel strips welded across the top face.

Simulate

Run it under your load. See where it gets hot.

MNA electrical solver and lumped thermal model. The simulation flags hot cells, voltage sags, and strip overloads before the welder fires.

The battery-builder editor in VALIDATE mode after running a simulation. Cells are heat-map coloured, the hottest cell highlighted.

Export

The artifact you take to the bench.

A printable build sheet with cell IDs, strip routing, dimensions, and the BOM. PDF or CSV. Open it on your phone, weld the pack.

My Pack build sheet

REV 1 · 11 May 2026

Topology

3S7P

Nominal

10.8V

Capacity

29.4Ah

Energy

318Wh

Bill of materials

CELL-01Molicel INR-21700-P42A21€7.49 / unit
STR-01Pure nickel strip 8 × 0.15 mm2062 mm avg
HLD-013D-printed holder (3S7P, PETG)2printable.stl
BMS-01JBD Smart 3S 30A common-port1€18.20
LD-0110 AWG silicone lead, 15 cm2red & black

Build order

01Spot-weld P-group strips, top faceS1 → S315 welds
02Flip pack, weld bottom face stripsS1 → S35 welds
03Solder balance leads to P-group tapsB1, B2, B33 taps
04Connect BMS, verify cell voltagesall groupswithin 0.05 V

Pricing

Free for builders. Paid when you sell.

The editor and simulator are free for personal use. Pay only when you start shipping packs to customers.

Hobbyist

Freeforever

For your own packs, your own bench.

  • 3D editor, hex-snap placement
  • Electrical + thermal simulation
  • Build sheet export (PDF, CSV)
  • Cloud save, up to 5 packs
Open the editor →

Workshop

€19/ month

When you're building packs for customers.

  • Everything in Hobbyist
  • Unlimited packs and revisions
  • Customer-ready build sheets, your branding
  • Pack version history and change-logs
  • Priority email support

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