The direct answer
Can two robot batteries be treated as interchangeable when nominal voltage and dimensions match? No. In this sample, seven of eight pack records publish SMBus, but only four publish both a protocol and Smart Battery Data Specification revision. Six publish an exact connector, mate and contact-function package. Seven publish a charger requirement or compatible model. None publishes a time-qualified pulse-discharge boundary, and none completes all ten RCI evidence fields.
Can a 21700 cell be compared directly with a removable robot battery? No. The three Molicel records are bare cells. Their charge voltage, cut-off, continuous current and temperature limits are useful for pack engineering, but the connector, fuel gauge, BMS, balancing, fusing, enclosure, thermal path and pack-level compliance do not exist at that boundary.
Zero does not mean the eight packs are incompatible or unsafe. It means public evidence is insufficient to issue a model-to-model drop-in recommendation without assumptions. The most common gap is universal: zero of eight packs publishes a time-qualified pulse-current limit in the selected evidence bundle.
Three hardware boundaries must not share one ranking
RCI’s eleven-record comparison originally mixed seven smart battery packs, one non-communicating pack family and three bare cells because all belong to robot power systems. RCI 019 preserves that discovery surface but separates the engineering boundary before making any compatibility statement.
| Boundary | Records | What exists at this boundary | What must not be assumed |
|---|---|---|---|
| Smart battery pack | 7 | Cells, protection, enclosure and a published digital pack interface. | Same SMBus name, pin count or footprint does not prove identical commands, alarms, authentication or charger behavior. |
| Non-communicating pack family | 1 | Protected rechargeable pack with multiple lead, connector and thermistor suffixes. | An unsuffixed family name is not a frozen connector or mechanical BOM item. |
| Bare 21700 cell | 3 | Cell electrochemistry and cell-level electrical, thermal and mechanical limits. | No pack connector, BMS, charger, fuel gauge, enclosure or pack certification. |
The eight complete-pack records
| Pack record | Voltage and discharge boundary | Connector evidence | Communication evidence | Charger and temperature |
|---|---|---|---|---|
| RRC power solutions RRC2054-2 Smart battery pack | 14.40 V nominal and 16.80 V maximum charge voltage; the selected source bundle does not publish a discharge cut-off voltage. 10.00 A maximum discharge current under pack protection and temperature limits. | Five contacts (+, C, D, T, −); RRC cable maps Bat+, SMBus-C, SMBus-D, SMBus-T and Bat−, and the product page lists exact MC20 mates. | SMBus; revisions not published SMBus is published, but no SMBus revision or Smart Battery Data Specification revision is attached to the current product page. | RRC-SMB-MBC is explicitly listed as suitable; charger communication and host power-path behavior still require system validation. Charge 0 to 45°C; discharge −20 to 60°C. |
| Inspired Energy ND2054HD29 Smart battery pack | 14.4 V nominal; the capacity test charges at 16.8 V and discharges to 10.0 V at 25°C. 4.0 A product-page current; pack protection and test conditions remain governing limits. | Exact AMP mating parts and terminal functions for positive, SMBus clock, SMBus data, thermistor and negative are published. | SMBus + SBDS revision published SMBus with Smart Battery Data Specification revision 1.1. | The specification requires a communicating smart-battery charger and the product page links compatible chargers. Charge 0 to 45°C; discharge −20 to 60°C. |
| Ultralife UBBL13-01 / UBI-2590 Smart battery pack | Series mode 20.0–33.6 V and 10 Ah; parallel mode 10.0–16.8 V and 20 Ah. No exact continuous-discharge current is retained in the selected product-page evidence bundle. | The BB-2590/XX90 interface is identified, but an exact host-side mate and complete contact-function table are not retained in this release. | SMBus + SBDS revision published SMBus 1.1 and Smart Battery Data 1.1 are published; multi-section or multi-battery hosts need an isolation or multiplexing design. | Official charging resources are linked, but this release does not pin one exact charger model to UBBL13-01. The product page publishes −32 to 60°C operating temperature, not a separate charge-temperature range. |
| RRC power solutions RRC2040-2 Smart battery pack | 10.80 V nominal and 12.60 V maximum charge voltage; no discharge cut-off voltage is published in the selected current page. 10.00 A maximum discharge current under protection and temperature limits. | Five contacts (+, C, D, T, −), exact cable signal mapping and exact MC20 mating accessories are published. | SMBus; revisions not published SMBus is published without an exact protocol or Smart Battery Data Specification revision. | RRC-SMB-MBC is explicitly listed as suitable for RRC2040-2. Charge 0 to 45°C; discharge −20 to 60°C. |
| Inspired Energy NH2054HD34 Smart battery pack | 14.4 V nominal; capacity test charges at 16.8 V and discharges to 11.0 V. 8.0 A product-page current and an 80 W continuous-power boundary. | AMP 5787422-1 or 5787446-1 mating parts, keying and positive/clock/data/thermistor/negative terminal functions are published. | SMBus + SBDS revision published SMBus with Smart Battery Data Specification revision 1.1. | The exact product page lists compatible CH- and CR-series charger models; the specification also requires Level II or III smart charging behavior. Charge 0 to 45°C; discharge −20 to 60°C. |
| RRC power solutions RRC2057 Smart battery pack | 7.20 V nominal and 8.40 V maximum charge voltage; no discharge cut-off voltage is published in the selected product page. 9.50 A maximum discharge current under protection and temperature limits. | Five contacts (+, C, D, T, −), exact cable signal mapping and exact MC20 mating accessories are published. | SMBus; revisions not published SMBus is named, but the exact SMBus and Smart Battery Data revisions are not published. | RRC-SMB-MBC is explicitly listed as suitable for RRC2057. Charge 0 to 45°C; discharge −20 to 60°C. |
| Inspired Energy NL2024HD22 Smart battery pack | 14.4 V nominal; the specification charges at 16.8 V and discharges to 12.0 V in the capacity test. 8 A maximum continuous discharge and 80 W maximum continuous power. | AMP 5787422-1 or 5787446-1 mating parts and positive/clock/data/thermistor/negative terminal functions are published. | SMBus + SBDS revision published SMBus with Smart Battery Data Specification revision 1.1. | The exact product page lists compatible CH1000/4000/4040/5000/5050/5555/6555/7000 and CR12 chargers. Charge 0 to 45°C; discharge −20 to 60°C. |
| Ultralife UBBL24 family Pack family; suffix not fixed | 7.2 V average, 5.0–8.4 V operating range; 8.4 V constant-voltage charge boundary. 3 A maximum continuous pack discharge at 23°C. | FL uses red/black leads, C1 uses JST VHR-2N and C2 uses Molex 22-01-3037; the catalog record does not freeze one suffix. | No pack protocol published No SMBus, CAN or other pack data protocol is published in the selected datasheet; thermistor-equipped suffixes are distinct orderable variants. | Ultralife UCH0037-S and UCH0037-I are published as optional chargers. Charge 0 to 45°C; the datasheet gives −20 to 60°C as the operating/discharge environment. |
The three current RRC packs publish a shared five-contact cable map and exact charger family, but their current pages stop at the name “SMBus” and do not attach a protocol or Smart Battery Data revision. Their maximum charge voltages are published; a discharge cut-off voltage is not. RCI therefore marks communication and the full voltage envelope partial.
The three Inspired Energy packs publish terminal functions, mating connector parts, SBDS 1.1 and a communicating charger boundary. NL2024HD22 is still not a simple default choice: the manufacturer labels it a legacy design and recommends alternatives for new products. UBBL13-01 publishes the versioned smart-battery protocol but leaves the selected connector/charger evidence partial. UBBL24 publishes distinct connector suffixes; the unsuffixed catalog record does not identify which one is being purchased.
Connector shape, contact order and SMBus are three different checks
A connector can mate mechanically while placing power, clock, data and thermistor on different contacts. RCI counts an exact connector package only when the source bundle identifies the mate and contact functions at the audited product boundary. Six of eight packs pass that field: three RRC and three Inspired Energy records.
Seven packs name SMBus. Only the three Inspired Energy packs and Ultralife UBBL13-01 state a versioned Smart Battery Data boundary. RRC’s official cable page is unusually useful because it maps Bat−, SMBus-T, SMBus-D, SMBus-C and Bat+ and names the compatible pack families. That still does not publish the current packs’ Smart Battery Data revision.
Multi-battery systems add another layer. UBBL13-01 contains two sections and can present series or parallel output. Ultralife’s integration guidance calls for SMBus isolation or multiplexing when multiple smart-battery nodes share a host. A bus name therefore cannot replace an addressing and power-path design.
Charging and temperature cannot be inferred from nominal voltage
Seven of eight packs publish a charger requirement or compatible model. The three RRC records name RRC-SMB-MBC; the Inspired Energy pages list compatible charger models or a communicating Level II/III smart-charger requirement; UBBL24 identifies UCH0037 variants. UBBL13-01 is partial because the selected release does not freeze one exact compatible charger.
Seven packs also separate charge and discharge temperature limits. UBBL13-01 only publishes a generic −32 to 60°C operating range on the selected page. That range must not be interpreted as permission to charge at −32°C. For RRC and Inspired Energy packs, the public boundary is typically 0 to 45°C charge and −20 to 60°C discharge.
Pulse load remains the largest cross-sample gap. Motors and actuators can create short current peaks, yet zero of eight pack records publishes a time-qualified pulse-current limit in the selected source bundle. A maximum or continuous-discharge number does not reveal pulse duration, recovery time, voltage sag, state-of-charge dependence, ambient temperature or protection trip behavior.
The three bare cells answer a different question
| Cell | Published cell boundary | Pulse / independent evidence | Why it is not a robot pack |
|---|---|---|---|
| Molicel INR-21700-P45B | 3.6 V nominal, 4.2 V charge voltage and 2.5 V discharge cut-off. 45 A continuous cell discharge with an 80°C cut-off under the datasheet condition. | The datasheet publishes 10-second power values; they are cell test boundaries, not a pack pulse-current guarantee. No exact-cell independent application dataset is selected in catalog v0.4.5. | A high cell-current rating cannot be transferred to a robot pack without cell matching, interconnect, BMS, fusing, thermal design, enclosure and pack-level validation. |
| Molicel INR-21700-P50B | 3.6 V nominal, 4.2 V charge voltage and 2.5 V discharge cut-off. 60 A continuous cell discharge under datasheet thermal conditions. | No separate time-qualified pulse-current limit is retained in the selected source bundle. No exact-cell independent application dataset is selected in catalog v0.4.5. | The cell’s 60 A headline is not a robot-pack continuous-current guarantee and cannot substitute for thermal, interconnect or pack certification work. |
| Molicel INR-21700-P42A | 3.6 V nominal, 4.2 V charge voltage and 2.5 V discharge cut-off. 45 A maximum continuous cell discharge under datasheet conditions. | An independent dataset publishes high-C pulse/GITT protocols, but it is not a manufacturer pulse-current design limit. Forty-five cells were screened and twelve were characterized at 5, 25 and 40°C; this validates the dataset scope, not pack compatibility or every production cell. | Exact-cell laboratory evidence narrows one cell boundary; it does not validate a robot pack, charger, connector, BMS or high-current enclosure. |
P45B is the only record in this release with a manufacturer-published 10-second cell power boundary. P42A is the only record with selected exact-model independent evidence: the dataset screened 45 cells and characterized 12 at 5, 25 and 40°C. Its pulse/GITT protocol is valuable cell evidence, but it is not a manufacturer pack current limit or a validation of one robot battery design.
Transport and safety documents do not prove electrical interchangeability
All eight pack records link or identify exact-product transport or safety documentation. The three cell pages list UL, UN, IEC and SDS resources, but the catalog boundary does not pin one exact report and revision, so RCI marks them partial. Either way, the evidence answers a different question from drop-in compatibility.
UN Manual of Tests and Criteria, subsection 38.3 governs lithium cell and battery transport testing. IEC 62133-2 covers safety requirements and tests for portable sealed secondary lithium cells and batteries. Neither standard supplies a robot’s contact map, SMBus data-set revision, charger protocol, pulse-load envelope or mechanical latch validation.
The ten-field pack disclosure matrix
“Published” means the selected evidence states a usable value at the exact audited boundary. “Partial” means a family, generic operating range, protocol name or standards list exists but does not close the field. Bare-cell connector and communication fields are excluded from the pack table below.
| Disclosure field | Published | Partial | Not published |
|---|---|---|---|
| Exact product / ordering-code boundary | 7 / 8 | 1 | 0 |
| Charge and discharge voltage limits | 5 / 8 | 3 | 0 |
| Continuous-discharge boundary | 7 / 8 | 0 | 1 |
| Time-qualified pulse-discharge boundary | 0 / 8 | 0 | 8 |
| Exact connector, mate and contact functions | 6 / 8 | 2 | 0 |
| Communication protocol and data-set revision | 4 / 8 | 3 | 1 |
| Charger requirement or compatible model | 7 / 8 | 1 | 0 |
| Separate charge and discharge temperature limits | 7 / 8 | 1 | 0 |
| Exact mechanical envelope | 7 / 8 | 1 | 0 |
| Exact-model transport or safety document | 8 / 8 | 0 | 0 |
Transport documentation is the only field published for all eight pack records. Seven publish an exact product boundary, continuous-discharge limit, charger boundary, separate temperatures and exact mechanics. Six publish the full connector/contact package. Four publish a versioned communication data boundary. Zero publish a time-qualified pulse-current boundary; therefore zero complete the matrix.
What to request before approving a battery substitution
- Identity: manufacturer, exact ordering code and suffix, hardware/firmware revision, cell revision and production-date boundary.
- Voltage: nominal voltage, charge ceiling, discharge cut-off, protection thresholds, state-of-charge range and allowable hot-swap voltage difference.
- Current: continuous current and a pulse table that states amplitude, duration, repetition, recovery, temperature, state of charge and end voltage.
- Connector: exact battery and host mating parts, polarization, latch, contact functions, current per contact, mating cycles and cable assembly.
- Communication: SMBus/CAN revision, data-set revision, address behavior, required commands, alarms, authentication and multi-pack arbitration.
- Charging: exact compatible charger or charge algorithm, temperature gates, precharge, termination, balancing and aged-pack behavior.
- Mechanics and environment: toleranced drawing, mass and center of gravity, retention, ingress, shock/vibration and separate charge/discharge/storage temperature ranges.
- Lifecycle and compliance: exact transport-test summary, safety certificate, shipped configuration, change-notification policy, approved source and counterfeit controls.
- Robot validation: start-up, regenerative events, motor peaks, brownout, cable loss, hot swap, fault handling and worst-case thermal duty on the production robot.
Method and limitations
RCI audited the eleven records already in the robot-battery comparison group as of 2026-08-10. The ten fields were selected to test public drop-in evidence, not general product quality. A field earns “published” only when the selected exact-product source states the boundary. A standards logo, generic family page, connector family, SMBus name or operating-temperature range earns partial disclosure when it leaves a material integration choice open.
Complete drop-in evidence is calculated only for pack records; a bare cell cannot pass by treating missing pack interfaces as not applicable. The audit does not test hardware, validate safety, confirm live inventory, establish regulatory approval for a destination or recommend a substitution. Manufacturer revisions can change, so every procurement decision must re-open the linked current documents.
Download the record-level data
Download the immutable research dataset as JSON or CSV. Stable current aliases are /data/research/robot-battery-compatibility.json and /data/research/robot-battery-compatibility.csv. The source catalog remains available as v0.4.5 JSON and its claim CSV.
For selection rather than audit detail, open the battery and cell evidence table and the six-layer battery compatibility guide.
Suggested citation: Robot Component Index, “Robot Battery Compatibility: 11 Records, 8 Packs, 0 Complete Drop-In Evidence Packages,” RCI 019, research dataset v0.1.0 and component catalog v0.4.5, 2026-08-10.