dogeTune

WORKSHOP & PROCESS

How we build a battery.

We follow one pack, a Razor 20S8P, from the first drawing to the finished case. Most photos are of that pack, taken in our workshop while we built and tested it. Where a step wasn’t photographed on the Razor, the caption says so.

RAZOR 20S8P · 160 CELLS · TWO SLOPED 10S8P MODULES · BUILT APRIL 2026

01 Design
02 Cut
03 Sort & measure
04 Holders
05 Insulation rings
06 Spot weld
07 BMS
08 Wrap & case
09 Load test

01 · DESIGN

Drawn in DogeTune Builder

The Razor’s battery space is a box with a sloped end, so a plain block of cells won’t fit. In DogeTune Builder, our own battery design software, we drew two 10S8P modules that follow the slope, then joined them into one 20S8P pack.

Builder checks that all 160 cells are placed and that the series chain is valid before anything is cut. Then the 3D preview shows the pack in layers: cells and busbars, the FR-4 wrap, and the metal case.

20 SERIES × 8 PARALLEL · 160 / 160 CELLS PLACED · PACK VALID · 259 × 177 MM FOOTPRINT

DogeTune Builder showing one sloped Razor 10S8P module marked Pack valid
The Razor project in DogeTune Builder: one 10S8P module, 80 cells, marked “Pack valid”.
Cell layout of a sloped Razor module, each cell numbered 1 to 10 by series group
The sloped module, each cell numbered by its series group.
3D preview of the Razor pack showing cells and busbars
Cells and busbars
3D preview of the Razor pack inside its FR-4 wrap
FR-4 wrap
3D preview of the Razor pack in its sheet metal case
Sheet metal case

02 · CUT

Busbars and sheets cut to the drawing

The busbars are cut to the shapes from the drawing, so each one lands on exactly the cells it’s meant to join. The FR-4 insulation sheets are cut on our CNC with the same slope as the pack.

A pile of cut copper and nickel busbars on the bench
The Razor’s busbars, cut and ready.
Sloped shapes cut into a yellow FR-4 sheet on a CNC bed
Sloped FR-4 sheets cut on our CNC.

03 · SORT & MEASURE

Every single cell sorted and measured

Before a cell goes anywhere near the pack, we measure it and sort it, on the tester and on our automatic cell sorter, so each group of eight is made of cells that match. It’s slow, and it’s the step most cheap packs skip.

Purple-sleeved cells being measured with a meter on the workbench
Measuring the cells before they’re grouped.
Automatic cell sorting machine with blue cells in its chute and sorting bins below
Our automatic cell sorter, here on another batch of cells.

04 · ASSEMBLE

Cells placed in their holders

The sorted cells go into holders (we call them crates) made for this layout, row by row, so every cell sits in the spot it was drawn in. The sloped FR-4 sheet goes alongside.

Purple cells lined up in a holder beside a sloped yellow FR-4 sheet
Razor cells in their holder, with the sloped FR-4 sheet beside them.
Workbench line with rows of purple cells and several Razor packs wrapped in FR-4 beside their cases
The Razor batch on our line: cells laid out, packs wrapped, cases waiting.

05 · INSULATE

Insulation rings pasted on

Before welding, an insulation ring is pasted onto the end of every cell. It’s a small part that’s easy to skip, and skipping it is how packs short out later.

Blue cells in a holder, some ends already fitted with green insulation rings and some still bare
Rings going onto bare cells before any busbars (another pack).
A sheet of green insulation rings beside a partly welded Razor module
A sheet of insulation rings next to the module, with rings on the cell ends under the busbars.

06 · SPOT WELD

Busbars spot welded on

The busbars are spot welded onto the cells one by one, joining them into the 20 series groups from step one. The modules are then joined into the full pack.

Spot welder firing sparks over copper busbars on a pack held in a jig
The spot welder firing on another pack.
Spot welder above a Razor module with nickel strips and a copper plate on ringed cells
The welder over a Razor module. The ringed cells at the top are next.

07 · WIRE UP

BMS wired in

The battery management system (BMS) is mounted on the pack and wired to every series group and to the main leads. It’s what watches the cells while you ride and charge.

Then we check every series group on a cell voltage tester. On this Razor, all 20 groups read between 3.528 V and 3.531 V.

Hands running white balance leads across the Razor modules on a turntable
Running the balance leads on the Razor.
Cell voltage tester screen showing all 20 series groups between 3.528 and 3.531 volts, next to the Razor BMS
Every series group checked: all 20 between 3.528 V and 3.531 V.

08 · WRAP & CASE

Wrapped, then cased

The modules are wrapped together in FR-4 insulation sheet, so nothing inside can rub or short against the case. Then the pack goes into its sheet metal case, the same one you saw in the 3D preview.

The Razor pack wrapped in yellow FR-4 with its balance leads out, on a turntable
The Razor in just its FR-4 wrap.
The FR-4 wrapped Razor pack beside its open black sheet metal case
The wrapped Razor next to the case it goes into.

09 · LOAD TEST

Load tested before it leaves

Last, the finished pack is wired to our load bank and tested, and we check the result on its BMS before it’s handed over.

The finished Razor pack with test leads attached and its BMS app open on a phone
The finished Razor wired up for its load test, with its BMS app open on the phone.
Coiled resistor load bank with a breaker and red test lead
Our resistor load bank.

FROM THE BUILD ARCHIVE

Shapes we’ve built

Same parts, different space. A step, a slope, a narrow bit below. See how the layout changes to fit the bike.

All builds

Awkward space or a demanding setup?

Send the usable dimensions, bike or equipment details, and whatever battery, charger and controller labels u have. We’ll talk about the whole build, not just a bigger number on the outside.

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