Understanding why your motorcycle won’t start after winter


Understanding why your motorcycle won’t start after winter


Understanding why your motorcycle won’t start after winter

The motorcycle battery is a crucial component in the bike’s triangle of power.


Triangle of Power

The triangle of power consists of the starter motor, alternator and the battery itself.

If any of these components are not performing to specification your bike will not start.

On a typical bike, the battery has five basic power supply functions:

Starting – Supplying power when cranking the engine.
Lighting – Delivering steady power before engine start.
Ignition – Supplying power to the ignition system during engine cranking.
Charging – Operating as a voltage stabiliser to absorb fluctuations in the electrical systems.
System Support – Supporting security systems and ECU memories whilst the ignition is switched off



Removing your old battery

Switch off your bike’s ignition, then detach the negative terminal, positive terminal, fixing bracket and exhaust tube (if applicable) in this order. Finish up by giving the area your battery sits in a good clean.

Fitting your new battery

Double-check that the new battery is the correct specification for your bike here.

Securely fix the battery using the bike’s bracket making sure that it is firm and will not move or vibrate excessively.

Attach the terminals, positive first, and re fit the terminal cover. If your battery came with a vinyl exhaust tube securely insert it into the battery’s exhaust elbow making sure that any vented electrolyte will avoid the rider’s leg and other components.

Why do bike batteries fail?

Remember, a battery is a consumable item. Just like brake pads or tyres its performance will naturally deteriorate over time until it needs replacing.

There are however several conditions that can lead to serious damage and premature battery failure. The following should be avoided at all costs:

Excessive Heat

Battery temperatures of over 50̊ C dramatically reduce service life. For every 10̊ C rise in temperature the battery’s natural self-discharge rate doubles meaning that it will discharge much faster.


Continuous discharging, low state of charge or low electrolyte levels can lead to a condition known as sulphation. This is where lead sulphate crystals build up on the lead plates reducing their surface area. Make sure your battery is properly charged and has correct electrolyte levels to prevent this.


If a battery is rattling around or vibrating excessively its internal elements could be damaged leading to short circuits and premature failure. Regularly check your bikes mounting equipment to make sure your battery is fully secure.


Yes, a battery can freeze, but usually only if it’s not charged adequately. When a battery is discharged it’s the acid in the electrolyte turns into water which can freeze at 0̊ C. If it freezes, replace the battery as damage and cracking to the case and internal components may have occurred.

If your battery is full charged you have nothing to worry about and it can be stored at sub-zero temperatures without issue.