What causes a Motorcycle Battery to go flat: what can we do to detect and prevent this?

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I have been experiencing issues with my Motorcycle Battery constantly going flat. Why is this happening?

Nothing is more irritating than getting ready for a ride and your Motorbike won’t start. Why does my Motorcycle Battery keep dying? It is a question we get asked often in our Workshop, so we have put together some information to save you from Flat Battery Frustration!

Which Motorcycle Battery do I have?

Before we can get into the ins and outs of best practices and things to check on your Motorcycle and Battery, it’s essential to understand the differences between Motorcycle Batteries and which one you currently use on your Motorbike.

Standard Type Battery

  • A Standard Lead Acid Motorcycle Battery. These are the original type of Motorcycle batteries. 
  • They are an Lead Acid Battery and require filling up with acid after purchase. 
  • If this is the type of Battery you are using, you will see a clear window allowing you to view fluid levels. 
  • You can also open this chamber and top up the fluid.  
  • If your Battery is dry, then the Battery will not hold a charge. 
  • Check that you have acid/electrolyte in the Battery.
  • The first thing we would do with a Battery at this stage is top it up with distilled water and charge the battery fully.
  • Now you can Test the Battery: hopefully, a quick and straightforward fix.

Maintenance Free Battery

  • This type of Battery is still a lead acid battery, but it has been designed not to be opened, thus reducing the opportunity for fluid loss and creating a Maintenance Free Battery.   
  • This type of Battery is filled from a fresh acid pack from the point of sale ( it will have a strip on it that says do not open)
  • Maintenance Free Batteries do not allow you to check the fluid contents.  
Maintenance Free Motorbike Battery

Gel Type (AGM) Absorbed Glass Mat) Battery

  • These batteries are pre-filled at the factory and made to be leakproof. It’s not possible to check the fluid level.

All three of these motorcycle Batteries mentioned above are considered Lead Acid batteries.

Maintenance Free Battery

Lithium Battery

  • These batteries are similar to the ones used in phones, laptops, and power tools. They are lightweight, with a higher cold cranking amp (CCA) rating for their size compared to other types of batteries. It is important to note that these batteries cannot be load tested using carbon pile testing and require digital versions for proper testing.

Motorcycle Battery Life

Like other types of batteries, motorcycle batteries do not have an infinite life. The most usual reason for a flat Battery is that it has come to the end of its life. A dead battery will not charge properly.

Check the condition of the Battery Terminals.

Other probable causes of a Battery being dead are corrosion of the battery terminals and a bad ground connection. A quick check of the terminals on your Battery to ensure no corrosion or dirt could fix your Flat Battery issue.  

We will problem-solve in this order if these simple checks do not get you anywhere.

One significant indicator of a battery issue is the timing of when it loses its charge.

If question number 1 or 2 of the statements below is confirmed, a battery cell is likely faulted. 

  1. My motorcycle battery is losing its charge overnight.
  2. My Motorcycle’s battery is dead as it has been sitting idle for a few weeks.
  3. I’m having issues with my motorcycle battery draining while riding it. (read further down)

In order to determine this, it is necessary to conduct a Battery Load Test.

The load test will determine whether the Battery is functioning correctly or if there may be an issue with the Motorbike.

What is a Battery Load Tester, and what is it used for?

  • A Carbon Pile Load Test will tell you if your Battery is holding a charge.  
  • There are two types of carbon pile load testers.
  • Variable and Fixed Load. 
  • A variable load test can be set to the batteries’ CCA (cold cranking amps).
  • A fixed load tester has a set load.
  • Both simulate trying to start the vehicle by drawing a large current from the Battery; they will have an analogue display.
  • Digital load testers that use virtual loads are available but are not as good for diagnostics.

How do I use a Battery Load Tester at Home?

  1. You will need a battery load tester (this example is for a variable load tester), a digital multi-meter, safety goggles, gloves, and a well-ventilated area. 
  2. Prepare the Battery: Charge it fully and let it rest for a few hours to stabilize before testing. 
  3. Connect the load tester: Connect the load tester to the battery terminals, following the manufacturer’s instructions. 
  4. Set the load: Set the load on the tester to the desired level, typically 50% or 100% of the Battery’s rated capacity. 
  5. Monitor the temperature: Keep an eye on the battery temperature throughout the test. If it starts to overheat, stop the test immediately.
  6. Monitor the Voltage: Use the digital multi-meter to monitor the battery voltage during the test. The Voltage should remain stable for the duration of the test. 
  7. If the needle holds the voltage constant during the test, the Battery is ok. 
  8. End the test: Once the battery voltage drops to the cutoff point, end the test and record the results.

Get My Battery Load Tested at MK1 Motorcycles.

Most Motorcycle Workshops will have a Battery  Load Tester that can easily and quickly tell you your Battery’s state.

We offer this service in our Motorcycle Workshops at Carrum Downs and Hastings. Book your Battery Testing by calling us at  9775 1299 or requesting a booking online.

Can I Load test a Lithium Battery?

No, a lithium battery can not be load tested. You can purchase a digital cold cranking amp tester, which will give an idea of how the Battery is fairing. 

Our workshop team can take care of this for you.

Digital Battery Tester

Ok so your Motorcycle Battery is testing fine during Load testing, but you are still experiencing flat battery issues? What Now?

1. One possible cause of this problem is a Parasitic Electrical drain:

This may occur due to aftermarket accessories or damage to wiring. We recommend conducting a Parasitic Drain Test to check for any current draw while the ignition is switched off. Although not common, this issue can occur and should be ruled out.

2. Another potential cause of a Flat Battery while riding is a malfunctioning charging system in the Motorcycle:

Undercharging fault

The Battery will not charge correctly while the Bike is being ridden. The charge drawn from the Bike’s electrical components will cause the Battery to go flat while riding.

Overcharging Fault

An Overcharging Fault can cause damage to the Battery, which may eventually result in the Battery no longer holding a charge.

Testing the Charging System of Your Motorbike

  • It is necessary to perform the test in a workshop unless you have a multimeter.
  • The test will be conducted with the Motorcycle both off and on.
  • If the Voltage does not increase, the Motorcycle is not charging.
  • If the Voltage rises and then plateaus at around 14 volts (depending on the vehicle’s charging system) as you bring the revs up, the Bike is charging correctly.
  • If the Voltage continues to increase, it is a sign that the Bike is overcharging. If there is a fault in the charging system, it could be due to a generator or regulator/rectifier issue.

Things to check when fitting a new Motorcycle Battery for the first time.

  1. Set up your new Motorcycle Battery Correctly.
  2. It’s essential to take the necessary steps to ensure its longevity and functionality. 
  3. Most batteries come with a small charge and can start your Motorbike, but it’s important not to cut corners. 
  4. A memory effect could occur if you do not FULLY charge a Lead Acid Battery, whether it’s a standard battery, a maintenance-free Battery, or a Gel Type AGM.
  5. It may never charge up past its original point, causing it to lose its charge altogether.
  6. Gel Type Maintenance-free batteries are particularly vulnerable to this effect. 
  7. Lithium batteries do not experience a memory effect, but it’s still best practice to charge them thoroughly before use.

Some tips for properly maintaining your Motorcycle Battery:

  1.  To ensure the best lifespan for your Battery, it is important to use it regularly and allow it to go through its discharge and charge cycle.
  2. However, if you plan on not using your Motorcycle for an extended period, it can be detrimental to the Battery’s health. 
  3. Purchase a charger that can run the Battery through the cycle is recommended.
  4. For lithium batteries, you should opt for a lithium-specific charger or a charger that enables you to switch between different battery types
  5. Lithium Batteries DO NOT need to be run through cycles.
MK1 Motorcycles or our sister shop, K1 Motorcycles in Hastings, will happily fill and pre-charge any Battery before you pick it up and after you have purchased it from us. That way, you can ensure your Battery is set up correctly and ready to use.If you need to have your Motorcycle or Battery tested, feel free to let us handle the diagnostic process for you.

Our workshops have a wide range of motorcycle battery brands available for purchase. These include , Rev Plus, and Motocell Lithium Gold.


Melbourne’s best Motorcycle Workshop is in Carrum Downs. We proudly serve Carrum Downs, Frankston, and neighbouring suburbs such as Sandhurst, Cranbourne, Seaford, and the Mornington Peninsula.

MK1 Motorcycles excels in seamlessly blending professionalism with a family-oriented approach. Our expert Bike Mechanics have extensive knowledge of Dirt and Road Bike Service, Repair, Diagnosis, Roadworthy Certificates, and Motorcycle Tyre Supply and Fitting.

Enjoy the convenience of our affordable pick-up and drop-off services. Unlike dealerships, we prioritise quality over quantity, ensuring personalised service marked by consistent communication and punctual work delivery.