Battery Building Tools Plan & Design

18650 Battery Pack Calculator and Planner

Plan a custom battery pack with live cell lookup, pack sizing math, runtime estimates, and BMS recommendations.

Configuration14S4P
Pack energy605 Wh
Pack capacity12.00 Ah
Suggested BMS14S 30A
1Select your cell

Search the cell database

Search by manufacturer or part number to prefill the core voltage and capacity fields.

If your exact cell is missing, enter the datasheet numbers manually and continue with the planner.

2Single cell information

Cell specs

These values drive everything downstream. Pull them from the datasheet or your own tested cells.

Single cell results

Watt hours (Wh)
10.80 Wh
Time to charge / discharge one cell
2 hours
3Pack configuration

Pack level information

Set the series and parallel counts, then confirm voltage, capacity, and current before moving on.

Quick pack presets

Pack results

Number of cells in the pack
56 cells
Nominal voltage of pack
50.40 V
Minimum pack voltage
39.20 V
Maximum pack voltage
58.80 V
Max discharge current
6.00 A
Estimated capacity of pack (Ah)
12.00 Ah
Estimated capacity of pack (Wh)
604.80 Wh
Estimated capacity of pack (kWh)
0.60 kWh

Pack voltage window

39.2V to 58.8V

Current headroom

WARNING: Load requires more amps than your pack and cells can safely supply. Add more cells in parallel or lower the load.

Runtime sanity check

0.60 hours estimated at 1000W draw.

4Runtime & load

Virtual battery life calculator

Estimate runtime at a fixed load to get a rough sanity check before you build anything.

Runtime results

Estimated run time
36 minutes
Pack discharge rate Warning
19.84 A

Estimated pack discharge rate is higher than the rated max discharge rate for the planned pack

5BMS & components
Pack Capability Warning

WARNING: Load requires more amps than your pack and cells can safely supply. Add more cells in parallel or lower the load.

BMS recommendation

Based on your current planner inputs, target a 14S 30A BMS.

Nominal pack voltage50.40 V
Minimum pack voltage39.20 V
Maximum pack voltage58.80 V
Pack max output6.00 A
BMS needs to handle25.51 A
Recommended class30 A
6Cost & weight

Pack weight and cell cost

This estimates only cell weight and cell cost. BMS, structure, nickel, wire, and enclosure still add overhead.

Cost and weight results

Cell cost of pack
$196
Weight of pack (g)
2,576 grams
Weight of pack (lbs)
5.68 lbs