Choose the cell and format
Start with the lithium-ion cell format that fits the application, including common cylindrical formats such as 18650 and 21700 cells.
Battery engineering tool
Custom Battery Pack Builder
Configure a custom lithium-ion battery pack using 18650, 21700 and other supported cell formats. Set the series and parallel arrangement around your target voltage, capacity and current, then submit the configuration to Voltaplex for engineering review.
Interactive configuration
Build Your Custom Battery Pack
Use the battery builder to configure a lithium-ion battery pack around your target voltage, capacity, current and cell format. After configuring the pack, Voltaplex can review the requirements for prototyping or production.
How it works
Configure a Battery Pack Around Your Requirements
Set series and parallel groups
Use the series count to establish pack voltage and the parallel count to scale capacity and available current for the required duty cycle.
Review the pack configuration
Check the resulting voltage, capacity, energy and cell count, then send the configuration to Voltaplex for an engineering and manufacturing review.
18650 configuration
18650 Battery Pack Builder
Configure an 18650 battery pack for the voltage, capacity and current your application requires. The final pack performance depends on the selected 18650 cell, series/parallel arrangement, BMS limits, thermal design and mechanical packaging.
21700 configuration
21700 Battery Pack Builder
Build around 21700 cells when the project benefits from a larger cylindrical format. Compare cell capacity, current capability and pack geometry before choosing the final configuration for engineering review.
Battery configuration guide
Series vs. Parallel Battery Configuration
Battery packs are commonly described with an S/P configuration. Series groups primarily determine pack voltage, while parallel cells increase capacity and can increase the current available from the pack when the selected cell and BMS support it.
Series (S)
Cells connected in series increase pack voltage. A 10S configuration contains ten cell groups connected in series.
Parallel (P)
Cells connected in parallel increase pack capacity. A 4P configuration uses four cells in each parallel group.
Example: 10S4P
A 10S4P pack uses 10 series groups with 4 cells in each group, for 40 total cells. Actual voltage, capacity and current depend on the selected cell.
What to evaluate
Key Battery Pack Requirements
A useful battery configuration should account for more than cell count. Review these requirements before moving from an initial calculator result to a manufacturable pack.
Nominal voltageTarget operating voltage of the configured pack.
Maximum charge voltageFull-charge voltage based on chemistry and series count.
CapacityPack amp-hour capacity based on the selected cell and parallel count.
EnergyTotal pack energy expressed in watt-hours.
Continuous currentCurrent capability must stay within cell, interconnect and BMS limits.
Total cell countSeries count multiplied by parallel count.
BMS requirementsProtection and control should match voltage, chemistry and current.
Mechanical designDimensions, enclosure, cooling, connectors and mounting matter.
From configuration to production
Need Voltaplex to Review or Manufacture Your Pack?
The battery builder is a starting point. A production-ready pack also needs appropriate cell selection, electrical protection, BMS design, interconnects, thermal management, mechanical packaging, validation and application-specific requirements.
Battery builder FAQ
Battery Pack Builder Questions
What is a battery pack builder?
A battery pack builder helps you define a starting configuration for a battery pack,
including the cell format and the number of cells connected in series and parallel.
The resulting configuration can be reviewed against the voltage, capacity, current,
dimensions and application requirements of the project.
How many 18650 cells do I need for a battery pack?
The number of 18650 cells depends on the required series and parallel configuration.
Multiply the number of series groups by the number of cells in each parallel group.
For example, a 10S4P pack contains 40 cells.
What is the difference between series and parallel cells?
Increasing the number of series groups increases pack voltage. Increasing the number
of parallel cells increases amp-hour capacity and can increase available current when
the selected cells, conductors and BMS are designed for it.
Can I build a battery pack with 21700 cells?
Yes. The battery builder can be used to plan packs around different cell formats when
supported by the app. The final design should account for the specific 21700 cell’s
electrical limits, dimensions and thermal requirements.
How is battery pack voltage calculated?
Pack nominal voltage is determined by the nominal voltage of the selected cell multiplied
by the number of series groups. Maximum charge voltage should be calculated separately
using the cell chemistry’s full-charge voltage.
How is battery pack capacity calculated?
Pack amp-hour capacity is primarily determined by the selected cell’s capacity multiplied
by the number of cells in parallel. Series count changes voltage, not amp-hour capacity.
Does a custom lithium-ion battery pack need a BMS?
Many rechargeable lithium-ion battery packs require a battery management system or other
protection electronics appropriate for the chemistry, voltage, current and application.
The required protection architecture should be confirmed during engineering review.
Can Voltaplex manufacture the configuration I build?
The builder provides an initial configuration. Submit the target voltage, capacity,
current, cell preference, dimensional constraints and application to Voltaplex so the
configuration can be reviewed for prototype or production requirements.
