Batteries, charging and classroom use

Nothing ends a robotics session faster than four robots that will not turn on. For a household this is an annoyance; for a classroom or a club it is the difference between a lesson and forty minutes of troubleshooting.

These are the specifications nobody looks at and everybody regrets.

Rechargeable or replaceable

Rechargeable robots are tidier and cheaper to run, and they are unavailable while charging. Replaceable cells mean a flat robot is working again in thirty seconds, which for a group is decisive.

For one robot at home, rechargeable. For six in a classroom, cells — or rechargeable with a charging rack.

Charging time versus run time

The useful ratio is how long a full charge lasts against how long it takes to reach it. Two hours of use from a two-hour charge is workable; forty minutes from a three-hour charge is not, for anybody running consecutive sessions.

Where a manufacturer states both figures, they are on our listings.

How many cables

A set of robots that all charge from one cable is a set that charges one at a time. Multi-port charging or a rack changes a session from a scheduling problem into a routine.

Worth budgeting for at the same time as the robots.

Battery doors

A door that needs a screwdriver stays shut. A door that clips stays shut until it is dropped. For any environment with more than one child, screws are worth the inconvenience.

It is also the most common repair on this shelf.

Firmware and updates

Some kits require an occasional update over an app. Doing this once, in advance, for every unit is a job worth scheduling rather than discovering. Kits that never need it are simpler to run and are worth preferring for group use.

Where updates are required, it is stated by the maker.

Pairing and identifying units

Six identical robots in one room means six devices that all look the same on a pairing list. Labelling both the robot and its entry in the app is the standard solution and takes ten minutes once.

Screen-free robots avoid this problem entirely, which is one of their quieter advantages.

Cards, mats and spares

Cards get lost, mats get torn and small parts disappear. Buying one spare set of cards per three robots is cheaper than a session where one group cannot work.

Check that spares are sold separately before committing to a system.

Storage between sessions

A box per robot with its cards, cable and mat is far more robust than a shared bin. It also makes it obvious immediately when something is missing rather than at the start of the next session.

Stackable clear boxes are the usual answer.

Floor surface

These robots are calibrated for hard floors. Carpet changes step distance and turning angle, which makes programs unreliable and looks like a fault. A mat solves it, and a mat is cheap.

Worth knowing before concluding a robot is inaccurate.

Noise in a room of six

One beeping robot is charming and six are not. A mute or volume option is a genuine feature for group use, and its absence is a real consideration.

It rarely appears in specifications and is worth asking about.

What to buy spares of

Cables, cards, and cells. Those three cover most failures. Motors and controllers rarely fail and are rarely worth stocking.

A small spares box costs very little and saves whole sessions.

Where to look

Robots and their accessories are on screen-free coding robots and app and remote robots; coding learning kits covers the electronics side.

The shop is on Harvard Avenue and can be phoned on the number on the contact page; the FAQ covers delivery and returns.

A checklist for the day before

Most session failures are preparation failures, and nearly all of them are caught by a five-minute check the day before rather than five minutes before. Turn every robot on. Confirm every one drives forward and turns. Count the cards in each box against the number that should be there. Check the mats are in the right boxes and the cables are with the units that need them.

That check finds the flat unit, the missing card set and the robot somebody left paired to a device that has gone home — all of which are trivial the day before and session-ending on the day. Clubs that adopt it stop having bad Tuesdays, and it is by some distance the highest-value habit on this list.

Keep the checklist physically with the boxes rather than in a document somewhere. A laminated card taped inside the lid of the storage crate gets used; a file on a laptop does not, particularly when the person running the session is a volunteer who did not write it.

Buying spares before you need them

The parts that fail on this shelf are entirely predictable: charging cables, instruction cards and battery cells, in that order. None of them are expensive and all of them stop a session dead. One spare cable per three robots, one spare card set per three, and a box of cells covers almost every interruption a club will meet in a term.

What is rarely worth stocking is a spare robot. Controllers and motors on established ranges very seldom fail, and a club that has budgeted for a spare unit would usually have been better off buying more mats. If a robot does fail inside its warranty, the manufacturer is the right route rather than a replacement purchase.