Free printableElectrical and wiringTSP-EL-02FLAGSHIP
Battery and charging system test sheet
Three voltage readings diagnose most electrical faults on these machines. Two thresholds are sourced; the rest is direction of change.
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TSP-EL-02 · version v1.0 · September 2026. Opens in your browser's PDF viewer, where you can print directly.
The problem it solves
A flat battery gets replaced, goes flat again, and gets replaced again — because the question was never which of three quite different faults was causing it. A battery that will not hold charge, a charging system not producing, and something draining it overnight all present identically and are found with the same meter in about twenty minutes.
Almost every electrical fault on these machines can be narrowed with three readings: what the battery reads rested, what it reads with the engine running and revved, and how much current is flowing with everything switched off.
The awkward part is that the reference numbers people quote for those readings are unreliable. When we traced the familiar state-of-charge chart back to a battery manufacturer, only the fully-charged row was actually a rested open-circuit figure — the rest were measured under load, which makes them depend on how much current is being drawn. And charging voltage figures for these machines disagree with each other inside a single forum thread.
So this sheet prints the two thresholds that are defensible, and for everything else asks for the direction of change, which needs no reference number to be useful.
The mistakes this sheet exists to prevent
- Measuring the battery straight after a ride or a charge, which reads high and means nothing.
- Replacing a battery that reads full. A full battery that will not crank is a connection fault.
- Concluding the charging system is fine because the voltage is above 12V with the engine running. What matters is whether it rose.
- Fitting a bigger battery to cure a drain, which buys a few days and finds nothing.
- Ignoring bulbs that keep blowing, which is a corroborating sign of overcharging.
Who it is for
- Anyone on their second or third battery in a year
- Owners whose machine goes flat if it stands for a few days
- Anyone who has been told the stator, regulator or CDI is at fault and wants to check first
What is on it
- Rested voltage thresholds, from a battery manufacturer, with the caveat that matters
- Charging behaviour as three observations rather than a target number
- The parasitic draw test with a sourced acceptable figure
- A running record so a fault that comes back is visible as a pattern
How to use it
- 01Take the rested reading before the first start of the day, or after several hours standing.
- 02Take the charging reading at the battery terminals, engine running, then revved.
- 03For the draw test put the meter in series with the disconnected negative lead, key off.
- 04Record every reading including the normal ones. A normal reading is evidence.
Also in a pack
Use it with the registry
Other sheets you may want
- Scooter starter clicks but will not turn overOne mechanical check first, then three electrical ones. The click itself tells you more than most people realise.
- GY6 wiring colour and continuity notes sheetThere is no universal wiring colour standard on these machines. This sheet records the one your machine actually uses.
- Scooter fuse record and circuit mapWhat fuse protects what, on a machine whose wiring diagram does not match anybody else's. Plus the blade fuse colours, from the manufacturers' datasheets.
Free to print, copy, and share — including in forums, clubs and workshops. If you find a mistake on this sheet, tell us and it gets corrected. Quote TSP-EL-02 and the version so we know exactly which sheet you mean. All printables.