Why this happens
Battery changes are gradual and easy to miss day to day, and single readings are affected by weather and riding style. A log turns scattered observations into a trend you can see on a chart. It also gives the service centre useful evidence if you need to make a warranty claim.
What you need
Tools
- Phone or computer with any spreadsheet app
- Plug-in energy meter (optional)
- Digital multimeter (optional)
Materials
- Your vehicle's odometer and charge gauge
- Battery label details
Before you start
- Do not take readings while riding; stop safely first.
- If you take voltage readings for the log, only measure at external connectors with the vehicle off and keep probes apart.
- A log helps spot trends but is not a substitute for professional diagnosis of a fault.
Step by step
- 1
Create the sheet and columns
Open a new spreadsheet and add these columns: date, odometer reading, charge level before charging, charge level after charging, charging time, energy from the wall in kWh (if you have an energy meter), ambient temperature, riding mode, notes. Add a separate tab for monthly checks such as resting voltage and connector temperatures if you do those.
- 2
Record battery details once
At the top or on a separate tab, record the battery's nominal voltage, Ah, energy in kWh, chemistry, serial number, purchase date and warranty period. Add the charger's output voltage and current. These details make your calculations easier and help with any warranty claim later.
- 3
Log every charge
Each time you charge, fill in a row before you plug in and finish it when you unplug. It takes under a minute. If you forget to note the starting level, leave the cell blank rather than guessing; gaps are better than wrong data.
Tip: Keep the sheet as a shortcut on your phone home screen so logging is quick.
- 4
Add calculated columns
Add a column for distance since the last charge, calculated as this odometer reading minus the previous one. Add a column for percentage used, before minus the previous after. Then estimate kilometres per full gauge by dividing distance by the fraction of gauge used. If you have energy readings, divide wall Wh by distance to get Wh per km.
- 5
Filter out unfair rows
Very short trips, unusual loads, long hill climbs or a pillion rider can make one row look odd. Add a yes or no column for typical use and filter on it when looking at trends. Note heavy rain or very hot days, which also affect range.
- 6
Chart the trend
Create a line chart of kilometres per full gauge or Wh per km against date, using only typical rows. Add a trendline if your spreadsheet offers one. Look at monthly averages rather than single points; seasons will cause a gentle wave in the line that is not damage.
- 7
Review monthly and act on changes
Once a month, look at the chart and the notes. A gradual decline is normal ageing. A sudden step down, much longer or shorter charging times, or rising connector temperatures are reasons to inspect the vehicle or book a service. Export the sheet as a PDF to show the service centre if needed.
How to tell it worked
After a few months you have a chart showing your real range and efficiency over time, with clear evidence of normal ageing or an early warning of a problem.
Stop and call a technician if
- The log shows a sudden large drop in range or energy between consecutive charges.
- Charging time becomes much shorter or longer than usual without explanation.
- Any physical sign of battery trouble appears, such as swelling, heat or smell.
Questions
How long before the log is useful?
Two to three months of regular entries usually show a clear pattern, and a full year shows the seasonal effect of heat and monsoon.
Do I need an energy meter?
No. Distance and gauge percentage are enough to track range. An energy meter adds Wh per km and charging cost, which makes the log more precise.