Layout parameters
1 mm leaves little convection path between wraps. 3 mm is usually the smallest spacing that clears the limit at higher currents.
Battery Building Tools Analyze & Validate
Find the hotspot before you weld it in
Interior cells have nowhere to send their heat. Set your spacing, current and cooling, and see which cells cross their limit — including the ones you'd never be able to touch once the pack is closed.
Hottest cell63 °C
Cell S2·2, dead centre. The limit is 60 °C — 15 cells are over it.
Per-cell current8.0 A40 A ÷ 5 parallel
Coolest cell48 °CCorner cell S1·1
Spread across pack15 °CAim for under 8 °C
Cells over limit15 of 35All interior, all unreachable
Estimated cell temperatureSteady state at 8.0 A per cell, 25 °C ambient
Temperature
≤ 40°
45°
50°
55°
60°
60°+
✕Over its own limit. The ring and ✕ are the verdict; the fill is only the temperature.
Hover a cell for its temperature and limit
15 cells cross the 60 °C limitFix requiredS2·2 – S6·4
What's wrong
At 8.0 A per cell with this spacing and cooling, the marked cells reach 63 °C — over the 60 °C discharge limit.
Why it matters
They are all interior cells: once the pack is welded and wrapped, they are unreachable and their heat has nowhere to go but the neighbours.
How to fix it
Add spacing between wraps, move to active cooling, or lower the continuous current until every cell sits under the limit.
Re-check runtime at a lower load →15 °C spread between centre and cornerWorth a lookS1·1 vs S2·2
What's wrong
The interior runs 15 °C hotter than the corners. Aim for a spread under 8 °C.
Why it matters
Hot cells age faster than cool ones, so a wide spread makes the pack drift out of balance long before any single cell fails.
How to fix it
Even the spread with airflow channels through the middle of the layout, or a wider grid with fewer rows deep.
Lay it out in the Designer →