Zero Motorcycle Glossary

Every term this site uses about a Zero, defined once. The words come off the motorcycle’s own log files, out of Zero’s manuals, and out of the figures this site computes from both — so each entry says which of the three it is, and links to the page that goes further.

Last updated: September 12, 2026

Boards, platforms and hardware

The parts of the motorcycle that write, carry or act on the data.

MBB(Main Bike Board): The motorcycle’s main controller. It supervises the motor, the dash and the interlocks, and it writes the MBB log — the file that holds rides, faults and, on most generations, the odometer.More: How Zero logs work
BMS(Battery Management System)Wikipedia: The board inside the battery pack. It measures every cell, decides what charging and discharging the pack will allow, and writes its own separate log. A bike with two packs has two of them, each with its own log.More: Battery fundamentals
Cypher III: Zero’s third-generation platform — SR/F, SR/S, DSR/X and S/F, plus the S, SR, DS and DSR from 2024. It records to a different log format from the earlier bikes, which is why a Gen3 file and a Gen2 file are read by different decoders.More: Gen2 vs Gen3: log differences
Sevcon: The motor controller fitted to the earlier bikes. Its faults reach the log as controller cutouts rather than as a battery or a motor fault, which is why a cutout is catalogued under the controller and not under either end of it.More: Log error catalog
PDU(Power Distribution Unit): The Gen3 replacement for ten of the individual fuses a Gen2 bike carries. It is why there is no headlight fuse and no accessory fuse to find on an SR/F: those circuits are switched inside the unit, and a failure is reported as a dash code instead of a blown fuse.More: The 12 V system
DC/DC converter Wikipedia: The device that makes the 12 V supply out of the traction pack. A Zero has no alternator: lights, dash, ECU and the auxiliary battery all live downstream of this one component.More: The 12 V system
Contactor Wikipedia: The high-voltage relay that connects the pack to the rest of the motorcycle. It is the thing that opens when the BMS decides the pack must stop supplying current, and a welded one is a fault the log names explicitly.More: Log error catalog
Isolation fault: A measured leakage path between the high-voltage side and the chassis. The bike reports that it detected one; it does not report where, so a log can raise the question and never answer it.More: Buying a used Zero

Log files and decoding

What a Zero actually records, in what shape, and for how long.

Log file (.bin): The binary file a board writes and you pull off the motorcycle. It is not a text file and not a database: it is a stream of fixed-shape records, which is why it has to be decoded rather than opened.More: How Zero logs work · Anatomy of a Zero log
Ring buffer Wikipedia: A store of fixed size that overwrites its own oldest record once it is full, so a log always holds the most recent history and never the whole of it. A parked Gen3 bike fills its buffer in about three days, which is how a rider ends up with a log that shows no rides at all.More: Why your Gen3 log shows no rides
0xB2 record: The framing of a Gen3 log entry: a marker byte, a length, a type and then the payload. The length is what lets a decoder walk the buffer at all, and the type is what says whether the record is a ride sample, a charge sample or a state change.More: Gen3 log format: the 0xB2 record spec
Console dump: The same history as text, read out over the motorcycle’s serial console with a command such as eventlogdump and captured by the terminal program. It is the way through when the binary cannot be read, and it is a genuinely different source, not a rendering of the .bin.More: Console log extraction (PuTTY)
Log entry: One timestamped line: a message, a state change or a set of measurements. Every figure on this site is an aggregate of these, which is why a log with few entries produces few answers rather than wrong ones.More: Anatomy of a Zero log
Generation (Gen2, Gen3): Which hardware family a bike belongs to. It matters here because it decides the shape of the log, not because it grades the motorcycle — the two generations record different fields, at different rates, into different record layouts.More: Gen2 vs Gen3: log differences
Dash code: The number the instrument cluster shows the rider. It is one of three separate vocabularies: a Gen2 diagnostic trouble code and a Gen3 error code with the same number are unrelated to each other, and the words a log file writes are a third set again.More: Error codes guide · Log error catalog
VIN(Vehicle Identification Number)Wikipedia: The seventeen characters stamped on the frame and printed in every log. Positions 1-3 are the manufacturer (Zero uses both 538 and PAG), and the rest carry the model line, the motor, the pack and the model year. It identifies a motorcycle; it is not a secret and it is not a credential.More: Zero VIN decoder: all 17 positions

Battery, capacity and charging

The vocabulary behind every capacity and state-of-health figure on this site.

SOC(State of Charge)Wikipedia: How full the pack is right now, as a percentage. The logs record it as a whole number, so a ride that really used 1.4% is written down as 1 — which is why a percentage this small cannot carry a capacity estimate on its back.More: Battery fundamentals
SOH(State of Health)Wikipedia: What the pack holds now against what it held when new, as a percentage. The number is only as good as its denominator, so this site states which one it used — the badge, the usable-when-new figure, or a measurement.More: Battery health & degradation
Maximum capacity (the ZF number): Zero brands its packs by maximum capacity: the ZF number is the pack maximum in kWh, so a ZF6.5 is 6.5 kWh at maximum. It is the badge on the bike, not an amount of energy a rider can draw.More: Battery catalogue
Nominal capacity: The same charge valued at nominal cell voltage instead of peak — roughly 0.87 to 0.88 times the maximum, so a ZF6.5 is published as 5.7 kWh nominal. Zero publishes both figures and uses the word “usable” for neither.More: Battery catalogue
Usable capacity: What a rider can actually draw, which is lower than either published figure: a BMS keeps a reserve at both ends of the pack. This site values it at 0.88 of the badge — the ratio backed by all 22 packs in Zero’s own catalogue, which run between 0.8750 and 0.8929.More: Battery health & degradation
Measured capacity: The pack’s own full-charge figure, read out of a BMS register. It exists only on the generations that record it, and it is a reading rather than a calculation — nothing about your charging habits can change it.More: Battery health & degradation
Estimated capacity: The figure computed from your own charge sessions: energy in, divided by the state of charge it bought. It is an INDEPENDENT quantity from the measured one and the two are not rivals — their expected ratio is the same 0.88, so a departure from it is the diagnostic signal, not a disagreement to average away.More: Battery health & degradation
28S(28 cells in series): The architecture of every pack in this catalogue: 28 cells in series, about 102 V nominal and about 117 V fully charged. The 2026 light line (LS1, XE, XB) is a different architecture at 74 V.More: Battery catalogue
Z-Force Li-Ion: Zero’s own name for the traction pack — “Z-Force Li-Ion Intelligent Power Pack” in the owner manuals. It names a product line, not a chemistry.More: Battery fundamentals
NMC(Nickel Manganese Cobalt)Wikipedia: A lithium-ion cathode chemistry, and — for a Zero — a community attribution rather than a specification. Zero’s manuals name neither the cathode nor the cell supplier for the traction pack, though they do print the chemistry of the 12 V auxiliary battery, so the silence looks deliberate. Treat it as what somebody worked out, not as what Zero states.More: Battery fundamentals
Power Tank: An additional pack that stacks onto a main pack rather than replacing it, so the bike carries more energy under the same badge. A bike with one has a nameplate that understates it — which is exactly the case where a measurement should outrank the badge.More: Battery catalogue
CC/CV(Constant Current, then Constant Voltage)Wikipedia: The two phases of a lithium charge: current held steady while the voltage climbs, then voltage held at the ceiling while the current tapers. The taper is why the last few percent take a disproportionate share of the time.More: Charging explained
Onboard and supplemental charging: The charger built into the motorcycle, and anything added alongside it. They appear in a log as different power levels on the same session, and a pack that stalls near the top on one and completes on the other is saying something about the pack, not about the chargers.More: Charging explained
Cell balancing: The BMS bleeding charge off the cells that are ahead so the rest can catch up. A pack is only as usable as its weakest cell, so imbalance costs range before it ever becomes a fault.More: Battery fundamentals
Derating: The bike deliberately reducing what it will allow, to protect something. Temperature is the common cause and the two limits are not the same: charging stops around 50 °C while riding continues to about 60 °C, so a hot pack can refuse the wall and still ride.More: Temperature limits and derating

Rides, sessions and derived figures

Numbers this site computes rather than reads, and what each one is measured from.

Regen(Regenerative braking)Wikipedia: The motor used as a generator, putting energy back into the pack while slowing the bike. In a log it is current flowing the same direction as charging, which is why current alone cannot tell a regen from a wall charge — the rest of the record has to.More: Riding & regen data
Ride session: A single journey as detected from the log: switch-on to switch-off, with the distance, energy and temperatures that fall inside it. It is derived, not recorded — the motorcycle stores events, not trips.More: Reading your logs
Charging session: A single charge as detected from the log, with the energy integrated over its own window. Because the energy and the window are the same measurement, a session with an impossible window has no usable energy figure either.More: Charging explained
Inferred charge: A charge recovered from a jump in state of charge rather than from charging current, for the bikes whose logs record the current too sparsely to see it. It is labelled as estimated and is kept out of every capacity figure, because a charge deduced from state of charge cannot then be used to measure state of charge.More: Charging explained
Odometer: The motorcycle’s own distance counter, read straight out of the log. It is a different quantity from the total of the rides this site detected: on a bike whose buffer has wrapped, the rides are a sample and the odometer is the whole history.More: Why your Gen3 log shows no rides
Efficiency (Wh/km): Energy out of the pack per kilometre covered. It is the honest comparison between two rides — speed, wind, weight, cold and elevation all land in it, which is why a single figure is a summary of a ride rather than a property of a motorcycle.More: Range calculator
GPX Wikipedia: The standard file a phone or a GPS app writes a track to. A Zero has no GPS receiver of its own, so route, elevation and cornering can only ever come from something you carried with you.More: Record a ride with your phone

Reading a log of your own

These words are worth more against a real file. Reading your logs works from a symptom to a conclusion, Anatomy of a Zero log annotates real extracts line by line, and the browser decoder reads a file without it leaving your machine.