Original equipment manufacturers (OEMs) looking to power mid-sized to large non-road mobile machinery (NRMM), electric transportation, and other equipment face the challenge of outfitting the products with larger batteries and more powerful chargers. But these machines often contend with space limitations due to their compact designs.
That said, OEMS can easily overcome spatial challenges by stacking chargers—providing greater charging power and achieving faster charging times. Below, we’ll break down how stackable charging works, its benefits, and additional considerations OEMs need to know.
What is Stackable Charging?
Stackable charging enables OEMs to flexibly achieve minimum charging power requirements for their machines to meet operators’ needs via multiple units. Because mid- and large-sized NRMM generally require more power and larger batteries, OEMs must choose between three options for charging solutions:
- Use the same charger as smaller machines with longer charge times.
- Install larger chargers to provide sufficient charging power and meet target charge times.
- Install multiple chargers that collectively provide sufficient charging power and meet target charge times.
The first option is anything but a solution and not viable. And the compact designs of mid-sized and large NRMM generally prohibit the second option—accommodating a singular charger capable of meeting the machine’s requirements might necessitate a complete systems reconfiguration.
Instead, OEMs can leverage stackable charging to place multiple chargers either directly together (if space allows) or in parallel throughout the machine.
Determining Charging Power Requirements for Stackable Chargers
OEMs can easily determine how many on-board chargers they need to stack to meet machines’ power requirements with a simple equation:
Battery size (Wh) = Charging time (h) x Charging power (W)
So, OEMs merely need to divide their machines’ battery size by how long charging should take—generally between 8 and 12 hours (i.e., “overnight”) at a maximum. Then, divide the total charging power required by an individual unit’s output to determine how many must be installed.
For example, each XV3300 charger produced by Delta-Q Technologies can provide 3.3 kW of charging power. Therefore, an 8 Wh battery would require a stack or parallel series of three chargers.
How Stackable Charging Functions
Stackable charging depends on the battery management system (BMS), charger software, and a CAN bus communications protocol (i.e., CANopen or SAE J1939).
One of the stacked chargers must be designated as the “primary charger” by installing a jumper wire on the COMM connector that transmits CAN bus data. This allows all charge management to function through the primary charger, such as:
- Load sharing in constant current modes
- System efficiency and optimization
- Thermal regulation
- AC current limit control (configurable)
- Faults and alarm monitoring
This integrated operation requires the BMS to identify the stacked or parallel units as a single charger, with “secondary” chargers transparent to the CAN system (i.e., not transmitting data). However, this system also supports seamless swapping between primary and secondary chargers if needed, as only the jumper wire connection needs to be changed.
Additional Benefits of Stackable Charging
Aside from scalable charging power, stackable charging provides OEMs with benefits such as flexible configurations, charger redundancy, and better margin opportunities.
Flexible Charger Configuration
Multiple chargers inherently provide OEMs’ design and engineering teams with greater flexibility for systems configuration. And for compact NRRM, this flexibility is crucial. Placing a single large charger on-board may not be feasible if other systems can’t be reconfigured.
However, it’s significantly easier to create smaller pockets of space within machines’ designs. For example, rather than needing to find 1200 cubic-inches (~19.5L), OEMs can utilize three separate spaces of roughly 400 cubic-inches (~6.5L) to provide equivalent charging performance.
Charger Redundancy
Multiple chargers provide NRMM with backup options should any individual units fail. With one charger out of commission, charging times will be slower. However, operators and fleet managers can still restore batteries to full capacity—either enabling work to continue on job sites or charging the machine enough to facilitate transportation for servicing.
This redundancy is especially crucial for operations that may place machines in work locations further removed from easy access (e.g., agriculture and outdoor power equipment (OPE)), as field calls for servicing quickly become expensive.
Higher Margins for OEMs
Stacking multiple chargers allows OEMs to deliver performance operators and fleet managers will be more willing to invest in.
Providing different battery or charger options for more range or faster charging, respectively, traditionally adds inventory management and configuration challenges (if using different charger models). And these may prove more troublesome than the obvious upsell opportunities different performance ranges create.
However, if OEMs design and engineer a machine to support multiple battery chargers, they can still benefit from those upsell opportunities. For example, suppose a machine requires a 3 kW charger but provides space to support up to two more units. With minimal complexity, that same machine can be sold as three different SKUs with varying performance levels. And because they all rely on the same charger, there are no inventory management issues to contend with.
Alternatively, even if minimum power requirements don’t necessitate larger or more chargers, OEMs can achieve substantial performance advantages over competitors via stacked chargers and the faster charging capabilities they provide.
Stackable Charging Configurations for OEMs
OEMs considering a stackable charging system should keep the following considerations in mind when seeking charger partners:
- Connectors – Greater charging power output requires connecting chargers to greater inputs. This necessitates connection to an industrial outlet or electric vehicle supply equipment (EVSE) for most NRMM. OEMs must ensure that the chargers they choose support compatible connections if the machine’s power requirements exceed 3 kW.
- Charger access – Whether OEMs design panels or choose another method, a stackable system’s ability to swap master and secondary chargers will require access. This is especially true when relying on charger redundancy if the master charger is the unit needing service or replacement.
- Configuration restrictions – Adequate protection will place some limits on stacked charger configurations. For example, passively cooled and fan-cooled units must be mounted correctly and with enough surrounding space to facilitate heat dispersal. Similarly, units mounted near areas exposed to liquids, solid particle sprays, and other work environment conditions will require higher IP ratings.
Stack and Scale Charging Power with Delta-Q Technologies
Delta-Q Technologies provides multiple chargers capable of stacking or parallel configurations, including the XV3300, the RC Series, and the ICL Series.
The XV3300—which recently entered full production—will provide machines with roughly 10 kW when stacking the maximum three units, and the liquid-cooled option supports greater configuration flexibility as it doesn’t limit mounting options. And with EVSE compatibility, the XV3300’s charging accessibility suits myriad applications, from NRMM to e-Mobility.
Contact Delta-Q Technologies to learn more about how stacked charger configurations can power your machines and devices to new performance levels.
