48 V Battery from VDA 355 Modules: Series Config Guide
Short answer: A 48 V battery built from VDA 355 modules uses either three 1P4S modules in series (43.9 V nominal, 33.6-52.2 V window) or two 2P6S modules in series (44.0 V nominal, 33.0-52.2 V window at operating temperature). Neither configuration produces a fixed 48 V; the equipment must accept the full voltage window from empty to fully charged.
Automated guided vehicles, industrial working machines and smaller marine vessels share a common electrical architecture: a nominal 48 V bus, a load that draws substantial current, and a pack that must fit a constrained envelope. VDA 355 modules, originally developed for passenger-car platforms, translate well into these applications because the format is mechanically standardised and the cell configurations are documented to a level that makes system calculations straightforward.
This article works through the numbers using catalogue data for two VDA 355 configurations: the 1P4S and the 2P6S. All figures are derived directly from those datasheets.
What the voltage window actually means
A VDA 355 module does not operate at a single voltage. It has a nominal voltage (a representative mid-point), a maximum voltage when fully charged, and a minimum voltage at the end of discharge. The equipment connected to the pack (charger, inverter, motor controller) must accept every point in that window, not just the nominal figure.
For a VDA 355 module in the 1P4S configuration, catalogue data gives: - Nominal voltage: 14.64 V - Voltage window: 11.2 V to 17.4 V - Energy: 2.59 kWh - Mass: 11.85 kg - Rated continuous current: 174 A
For the 2P6S configuration: - Nominal voltage: 22.02 V - Voltage window: 16.5 V to 26.1 V (0 °C to 55 °C operating range) - Low-temperature window: 13.2 V to 26.1 V (-30 °C to 0 °C) - Energy: 2.55 kWh - Mass: 12.2 kg - Rated continuous current: 116 A
When modules are connected in series, nominal voltages and window limits add directly. Energy content adds directly. Rated current remains that of a single module; it does not increase with series connection.
Worked configurations for a 48 V system
Three 1P4S modules in series
Three 1P4S modules placed in series produce: - Nominal voltage: 3 x 14.64 V = 43.9 V - Voltage window: 3 x 11.2 V to 3 x 17.4 V = 33.6 V to 52.2 V - Total energy: 3 x 2.59 kWh = 7.77 kWh - Module mass: 3 x 11.85 kg = 35.6 kg - Rated continuous current: 174 A (string current, unchanged) - Continuous power at rated current: 43.9 V x 174 A = approximately 7.6 kW
The charger must reach 52.2 V to charge the string fully. The motor controller or inverter must continue to operate down to 33.6 V at the end of discharge. Any equipment specified only to 48 V nominal without an adequate window margin will either cut off early or never reach full charge.
Four 1P4S modules in series
Four modules in series shift the window upward: - Nominal voltage: 4 x 14.64 V = 58.6 V - Voltage window: 44.8 V to 69.6 V - Total energy: 4 x 2.59 kWh = 10.36 kWh
This configuration tops out at 69.6 V, above what much equipment labelled as 48 V accepts. Use it only where the drive and charger explicitly accept that window.
Two 2P6S modules in series
Two 2P6S modules in series give: - Nominal voltage: 2 x 22.02 V = 44.0 V - Voltage window (above 0 °C): 33.0 V to 52.2 V - Total energy: 2 x 2.55 kWh = 5.1 kWh - Rated continuous current: 116 A
At temperatures below 0 °C the lower cell limit drops, and the string minimum falls to 26.4 V. If the application operates in cold environments, the equipment must either tolerate that lower cutoff or the BMS must impose a higher discharge cutoff to protect the cells and keep the bus voltage within the equipment's input range.
Configuration comparison table
| Configuration | Modules | Nominal voltage | Voltage window (operating temp) | Energy | Module mass |
|---|---|---|---|---|---|
| 3 x 1P4S in series | 3 | 43.9 V | 33.6 V - 52.2 V | 7.77 kWh | 35.6 kg |
| 4 x 1P4S in series | 4 | 58.6 V | 44.8 V - 69.6 V | 10.36 kWh | 47.4 kg |
| 2 x 2P6S in series | 2 | 44.0 V | 33.0 V - 52.2 V (0 °C to 55 °C) | 5.10 kWh | 24.4 kg |
| 2 x 2P6S in series (cold) | 2 | 44.0 V | 26.4 V - 52.2 V (-30 °C to 0 °C) | 5.10 kWh | 24.4 kg |
The 3 x 1P4S string offers more energy and higher continuous current than the 2 x 2P6S string at comparable nominal voltage, which suits higher-power duty cycles. The 2 x 2P6S option is lighter, which may matter in a compact AGV chassis.
Parallel strings: more capacity, more coordination
Running two strings in parallel doubles capacity and current capability. It also introduces requirements that must be addressed in the system design. Strings should be at equal voltage before they are connected; a significant voltage difference between strings at the moment of connection produces a current surge that the cells were not designed to absorb. The BMS architecture must account for each string independently, with protection and balancing applied at string level. What the BMS covers, and how strings are managed, is defined per project rather than being a fixed scope of the module itself.
Compliance considerations
Safety requirements differ by voltage class, and the applicable standard depends on the application. A marine installation, an AGV operating in a logistics warehouse and a mobile working machine each fall under different regulatory frameworks. The voltage window of the assembled pack determines which class applies; the relevant standard for the specific application is the governing reference. EU regulation covering lithium batteries sets broader requirements on documentation, traceability and end-of-life handling that apply across applications regardless of voltage class.
Transport of lithium cells and modules is governed by UN 38.3, published by the United Nations Economic Commission for Europe (UNECE), which sets the testing protocol that cells must pass before shipment. This is a pre-condition for logistics, not a system-level safety certification.
Practical notes for integrators
VDA 355 modules were developed for automotive platforms. That origin means the format is defined by its outer dimensions, which is one of the main advantages of the VDA 355 format for pack builders. Terminal positions and thermal interfaces still differ per product, so check them against the datasheet before you design the pack structure.
For AGV and marine applications, thermal management deserves attention. The 2P6S low-temperature window shows how significantly the usable voltage range can shift in cold operation. In sub-zero environments, a heater circuit or a BMS-imposed discharge floor is one way to keep the bus voltage inside the equipment's operating range.
For current sizing: the 174 A rating on the 1P4S and 116 A on the 2P6S are continuous ratings. Peak currents during acceleration or regenerative braking must be checked against the module's pulse rating, which is stated per product in the datasheet. Do not use the continuous rating as a proxy for pulse capability.
Avantis Energy lists VDA 355 modules in both 1P4S and 2P6S configurations.
Frequently asked questions
How many VDA 355 modules do I need for a 48 V battery?
Three 1P4S modules in series give 43.9 V nominal and a 33.6 V to 52.2 V window, which is the closest match to a 48 V bus. Two 2P6S modules in series give 44.0 V nominal with the same upper limit. Four 1P4S modules in series produce 58.6 V nominal, which exceeds most 48 V equipment limits at full charge.
What voltage must my charger and motor controller accept for a 3 x 1P4S string?
The charger must reach 52.2 V to fully charge the string. The motor controller or inverter must operate down to 33.6 V at end of discharge. Equipment specified only to a fixed 48 V without that window will either fail to charge fully or shut down before the cells are empty.
Does cold temperature affect the voltage window of VDA 355 modules?
Yes. The 2P6S module has a lower voltage limit of 16.5 V above 0 °C, which drops to 13.2 V between -30 °C and 0 °C. In a two-module series string, the pack minimum falls from 33.0 V to 26.4 V in cold conditions. Equipment must either tolerate that range or the BMS must impose a higher cutoff.
Does connecting modules in parallel increase the current rating?
Yes. Two strings of 3 x 1P4S in parallel double the available continuous current and double the energy, while nominal voltage and voltage window remain unchanged. Strings must be balanced to equal voltage before connection, and BMS architecture must manage each string independently.
Are VDA 355 modules suitable for AGV and marine use?
VDA 355 modules were designed for automotive platforms but are applied in AGVs, working machines and smaller vessels because the standardised format suits compact pack design and multi-source procurement. The integrator must verify that the full voltage window, thermal range and applicable safety standards for the specific application are met in the system design.
Specify your 48 V pack
Discuss your pack requirements with Avantis Energy to confirm module selection and string configuration for your application.