When an off-the-shelf battery is enough
An off-the-shelf battery is the right choice when none of the five reasons for a custom build applies. That is the case when all four points hold at the same time: Installation space uncritical — the battery does not have to fit into a predefined geometry. Weight irrelevant to the application. Load profile moderate — no high continuous currents, no 1C–2C fast charging, no extreme cycle counts. No deep communication with a machine controller required — a simple SoC signal is enough.
If that is the case, a standard pack saves development effort — anything else would be over-engineered.
Five reasons that force a custom build
As soon as one of these points applies, standard ends — and in each case the reason is physical, not cosmetic.
Installation-space restriction: The bay in the chassis has a fixed geometry. A standard cuboid often only uses 60–70 % of it; a pack designed around the installation space reaches 90–95 %. That difference is directly usable capacity — and therefore range per charge.
Load profile and cycles: Multi-shift operation with high daily charge throughput over 8–10 years demands a cell selected for that profile and a BMS parameterisation that tunes charge rate, DoD and balancing accordingly. A standard parameterisation ages prematurely under this profile.
Temperature extremes: Cold-chain logistics at −30 °C or outdoor operation demand cold-capable cells and active preheating, because charging below roughly 10–15 °C at a high rate damages the cell through lithium plating. A standard pack without a heating concept cannot be operated here on a lasting basis.
Communication interface: AGVs and AGCs communicate via CAN bus, CANopen or proprietary protocols. The BMS has to be matched to the object dictionary and the fault behaviour of the machine controller; a standard pack with fixed mapping cannot be adapted.
Certification and product liability: Whoever builds a battery into their machine carries the product liability. A custom battery with its own technical documentation and a CE declaration of conformity from the battery manufacturer separates the liability cleanly and relieves the OEM.
From practice: ROBOT-40
An example that shows the sequence: for the ROBOT-40 by GKS/Georg Kramp, an autonomous heavy-duty AGC for up to 40 t that has been in service worldwide since 2013, no off-the-shelf battery fits the vehicle to this day. The installation space was predefined, the load profile at 40 t payload is harsh, and the system had to run without long standstills at the charging point. We therefore developed two custom batteries with a purpose-built enclosure and a battery-swap system that decouples charging time from vehicle availability. No catalogue product could have met these four restrictions simultaneously. That is exactly the normal case with special-purpose vehicles, not the exception.
The path from requirement to series from unit 1
A project runs in four phases: requirements capture (load profile, installation space, interfaces, certification target), prototype, field test at the customer under real conditions and series production. Decisive for special-purpose vehicles and small series: the series starts at unit 1. You do not have to commit to a minimum order of hundreds of units to get a suitable pack; we have manufactured from Lower Austria since 2004, from the very first unit, in LiFePO4 and Li-NMC.
The return on investment comes over the service life, not over the unit price
A custom pack costs more in development than a catalogue part. But the comparison that counts is not the purchase price, it is the cost over the service life. A pack designed for the load profile, that keeps the cells within the temperature window and balances them cleanly, reaches its specified cycle count instead of going into the workshop after 14 months. For a vehicle whose downtime costs money by the hour, the additional effort pays off through avoided failures and the later replacement.
Decision rule
Installation space, weight, load profile and communication uncritical: choose an off-the-shelf battery. One of the five reasons (installation space, load profile, temperature, communication, certification) applies: custom build. Calculate on lifetime cost, not on the unit price. For special-purpose vehicles and small series: the series starts at unit 1, no minimum quantity required.
If you are unsure whether your use case goes beyond standard, that can be clarified against the five reasons in a single conversation. We are happy to discuss the design.