Skoolie glossary

The vocabulary, in plain language. 30 terms.

AFF: Above finished floor. The height a fixture is mounted, measured from the floor you will actually walk on rather than the bare metal. Used throughout the floor plan designer.
Amp-hour (Ah): A measure of battery capacity: one amp drawn for one hour. Compare banks at the same voltage, or convert to watt-hours (Ah x volts) to compare fairly across 12V, 24V and 48V systems.
Black tank: The holding tank for toilet waste on a bus with a conventional flush toilet. Must be emptied at a dump station.
BMS: Battery management system. Electronics inside or alongside a lithium battery that prevent over-charge, over-discharge and, critically in a bus, charging below freezing.
Boondocking: Camping without hookups, off grid, usually on public land. The scenario that drives solar, battery and water capacity decisions.
Buildable length: The floor length you can actually build in, once the hood, cowl and any engine bay are subtracted from overall length. Always the number that matters, never the advertised length.
Cowl: The structure between the hood and the windscreen on a conventional bus. Part of the dead space ahead of the entry door.
Curb side: The right-hand side of a US bus, where the entry door is, so passengers step onto the pavement. The opposite of the driver side.
DC-DC charger: A device that charges the house battery from the engine alternator at a controlled rate. Essential with lithium, which will otherwise draw more current than an alternator can survive.
Depth of discharge (DoD): How much of a battery's rated capacity you actually use. Lithium tolerates deep discharge; lead-acid does not, which is why a 200Ah lead bank gives far less usable energy than 200Ah of lithium.
Dump station: A facility for legally emptying black and grey tanks. Finding them is a real constraint on how you plan water capacity.
Grey water: Waste water from sinks and the shower. Rules on where it may be discharged vary enormously by jurisdiction — check locally rather than assuming.
GVWR: Gross vehicle weight rating. The maximum the vehicle may legally weigh fully loaded. Subtract curb weight to get payload, which is what a conversion has to fit inside.
House battery: The battery bank that runs the living space, kept separate from the engine starting battery so you cannot strand yourself by running the lights all night.
Hydronic heat: Heating that circulates hot coolant through a loop to radiators, a heater core or in-floor tubing, rather than blowing hot air directly. Can also make domestic hot water.
Inverter: Converts battery DC into household AC. Rated for continuous output and a higher surge figure — size for the surge, or motors will trip it.
LiFePO4: Lithium iron phosphate. The dominant house battery chemistry in conversions: long cycle life, deep usable capacity, and safer than other lithium chemistries. Cannot be charged below freezing without internal heating.
MPPT: Maximum power point tracking. A solar charge controller that converts excess panel voltage into usable charging current, typically recovering 20-30% more energy than a cheaper PWM controller.
Payload: GVWR minus curb weight: what you can add. On a small Type A bus this is the number that decides whether a full build is even viable.
Peak sun hours: The number of hours per day equivalent to full-strength sun at your location. Used to convert a solar array's rated watts into realistic daily watt-hours. Varies by season and latitude.
Roof raise: Cutting the roof off and lifting it to gain standing headroom. The single most transformative and most structurally serious modification, and one that must be decided early.
Rub rail: The horizontal steel ribs running along the outside of a bus body. Useful landmarks: they mark the floor line and the seat line inside.
Shore power: Mains electricity from a campsite pedestal or a house, fed into the bus through an inlet and usually a converter or charger.
Shunt: A precision resistor through which all battery current passes, letting a monitor report true state of charge. Far more reliable than guessing from voltage.
Skirt: The lower body panels below the floor line, outside the frame rails. Often where rust starts, and where underslung tanks and battery boxes get mounted.
Skoolie: A school bus converted into a home or camper, and by extension the community around doing so.
Type A / B / C / D: School bus classifications. A is a body on a cutaway van chassis (narrow). B is full width but short. C is the classic conventional with a hood. D is flat-nosed with the best length efficiency.
Wet bath: A bathroom where the shower is not separated, so the whole room including the toilet gets wet. Space-efficient, and it constrains which toilet types are sensible.
Wheel well: The intrusion of the rear axle into the floor, typically about a foot on each side. Plan the bed, seating or cabinetry around it rather than fighting it.
Wheelbase: Distance between front and rear axle centres. Within one model, wheelbase largely determines overall length, which is why used listings quoting only the model name tell you little.