A guide to lawn mower batteries
Tom Vondrasek | 13th Dec 2023 | 5 minutes to read
With so much land in Australia, ride-on lawn mowers are extremely popular. They can cut large areas of grass and scrub and have the flexibility of going around trees, bushes, and garden beds.
With Australia being known for its bushfires they are also a great way of keeping the land clear around houses to help decrease the risk of fire danger. A ride-on mower is like a small tractor, so much so that tractor companies like John Deere and Kubota offer them in their range. Most are petrol or diesel driven, though pure battery-powered electric (EV) ride on mowers are on the increase.
Petrol or diesel mowers, just like cars and boats, need a start battery to fire or start the engine.
The battery is a plastic box with 2 terminals (+ & -) that contains an acid (electrolyte) and lead plates. This box generates electricity and is a standard lead acid battery (wet cell). Once it starts the alternator/generator, which runs off the engine, starts providing the electrical power. It also has the function of recharging the battery, so it is topped up and ready to go when you next turn the key or push a button to start the engine.
Below are some important things to understand when looking for a lawn mower battery:
Start Batteries Explained
Electronics
Start batteries have one primary role and that is to start the engine. In a modern vehicle their secondary role is to keep the electronics alive before the engine is restarted. Even a ride on mower is not immune from having electronics control the engine. The good part is there is no central locking or other ancillaries that make changing a battery more complex.
The electronics draws very minimal power compared to starting the engine. It will eventually flatten the battery, with a ride-on lawn mower’s battery usually lasting around four weeks if left unused.
As lawn mower batteries are not always used regularly, a good idea is to use a battery charger to keep the battery topped up. Clever chargers these days monitor the battery and charge it only when necessary.
In terms of replacing the battery, the lifespan of a ride-on lawn mower battery can be anywhere from three to five years, so if your mower is getting on a bit and the battery isn’t holding charge, it might be time to replace it.
Battery Power (CCA)
The power required to start an engine is massive. The battery normally only needs to supply it in short bursts if your engine is healthy. A few rotations and the engine bursts into life. When that is not the case and the engine is cranked for a longer period, then it takes a toll on the battery. After a few attempts you can hear the starter motor slow down as the battery begins losing its edge. This is why short starting attempts are better for the battery.
This massive power is measured in CCA or Cold Cranking Amps. Breaking it down:
- Cold – The engine is cold or has not been started. This takes more power than a warm engine.
- Cranking – Rotating or turning over the engine
- Amps – The Ampere is an electrical measurement for current flow. The greater or higher the number of Amps, the more electricity flows down the cable.
Start batteries all have this rating (they are tested on it). It is the amount of current a battery can supply for 30 seconds at 0 degrees Fahrenheit.
Generally speaking, you’ll likely want a ride-on mower with a minimum CCA of 145, so make sure you check the specifications on the manufacturer’s website or in-store when purchasing a battery for your mower.
Engine Size, Petrol, & Diesel
The bigger your engine the larger the battery you need to start it. This makes sense as a larger engine will take more power to rotate the moving parts than a smaller engine. Even in the case of a single cylinder engine, a larger size engine needs more effort to rotate it.
A diesel engine runs a higher compression ratio. This means it compresses its fuel/air mixture to a greater degree than a petrol engine. This high compression causes a lot more resistance for the starter motor to overcome when rotating the engine to start it. The result is a diesel engine that is 2 litres in capacity requires a more powerful or higher CCA rated battery to start it than a 2-litre petrol engine.
Selecting the Correct Battery for Your Lawn Mower
Ride-on lawn mower batteries come under different group battery sizes that are given by the Battery Council International (BCI), with most batteries coming under the Group U1 title.
Positioning of the terminals is important to note as well, with Group U1 offering two variations: U1L and U1R, indicating a terminal position of the top left of the battery and the top right respectively.
It’s crucial that the positioning is the same so that the cabling will fit correctly.
These two features, along with the CCA of the battery, and whether you have a 6 volt or 12 volt battery (most ride-on mowers are 12 volt) are the most important features to look for when replacing your lawn mower’s battery.
When it comes to replacing a lawn mower battery always check your owner’s manual. Most are extremely simple and straight forward, requiring basic hand tools to take out and replace the battery. Checking the manual makes sure it is straight forward and there is nothing special you need to do.
Replacing Your Lawn Mower Battery at Repco
The best course of action when replacing your battery is to simply bring your old one into a Repco store and the store staff can change it over for you. This way, you can be sure you’re getting the correct battery for the job and your old battery gets sent off to be recycled.
If you already know the specifications for your lawn mower battery, then you can simply buy online from the comfort of your home.
