How to maintain a Lawnmower Battery

← Go back

Battery Care & Maintenance

The right care is essential to maximise the life of your Lawnmower or Lawn Tractor battery

Typically, a lawnmower or lawn tractor battery should last between three and five years, but to achieve this it is important you regularly maintain the battery. People often think when they’re not using their lawnmower or lawn tractor that the battery will remain charged and be ready for when they next use them. The truth is batteries will naturally discharge even when you’re not using them. That’s why you should ensure they are kept topped up with charge, using the correct battery charger, so the next time you want to mow your lawn you won’t be disappointed. During this help section we will refer to “lawnmower” but remember this can include “lawn tractors” for ease of explanation.

Regularly checking the level of charge in your battery is good practice to ensure you achieve the best possible battery life.

When it comes to lawnmower battery maintenance, you will first want to establish what type of battery technology you have. For instance do you have a standard wet flooded battery? Or may be you have the more modern and popular AGM battery? You might find you have a Lithium battery, while the basics are the similar we will help establish a basis for you to maintain your lawnmower battery.

Wet Flooded Battery

Your standard wet flooded (12 volt) battery will have six filler caps at the top, which is where the electrolyte (acid) is added when the battery is activated when new. When you have a wet flooded battery you have to make sure the acid level is between the lower level and the upper level marked on the battery, if you need to top up the battery, use distilled water (not tap water) and use the filler caps to do so. During your maintenance, you want to keep the battery clean and make sure the terminals are free of corrosion, as this can lead to many problems. If you find any corrosion or damage to the battery cable or terminals, you may want to seek professional advice as they are likely to need replacing. If you need to clean the battery and the terminals then a mixture of water and baking soda will be needed, it is also an ideal time to clean the battery tray from any residue acid that may be present, this can be done when the battery is removed to charge it during your maintenance schedule.

Regularly check the level of charge in the battery and recharge as required on the appropriate battery charger, if you are using the lawnmower regularly, then it’s likely you may not need to charge it as much. If you are planning on storing your lawnmower, perhaps over the winter, then you will want to remove the battery from the lawnmower (keep the battery inside, ideally in a garage), check that there is sufficient acid by using the levels marked on the battery and fill if required. Prior to storing your battery you want to make sure the battery is clean and free of damage, ensuring the terminals are free of corrosion and fully charge the battery.

If you happen to use your lawnmower all year round then sticking to the above will help get the most out of your lawnmower battery, however if you are planning on storing your lawnmower over the winter then please see storing a lawnmower battery.

AGM Battery

When it come to maintaining your Lawnmower battery that has AGM technology, you’ll be pleased to know there isn’t as much maintenance to do as with a wet flooded battery. This is because AGM (Absorbed Glass Mat) batteries are fully sealed and so once they have been activated from new, they are closed and as such they don’t require any electrolyte or water. All of that said, you will still need to regularly check the charge level in your battery and charge as required. Also keeping your battery and terminals clean and free of corrosion will prevent many problems from occurring. When cleaning your battery, terminals or the battery tray then using water and baking soda is a great solution.

Lithium Battery

As with the AGM battery, there is relatively little maintenance to do on Lithium batteries unlike the wet flooded lead-acid battery. You must make sure you regularly check the charge level of the battery and charge as required. When storing a Lithium-ion battery, disconnect the battery from the lawnmower and immediately charge the battery on a Lithium battery charger, the battery can then be happily stored for up to a year. When you wish to use the battery after storage, put the battery on charge so you have full power prior to use. Also keeping your battery and terminals clean and free of corrosion will prevent many problems from occurring. When cleaning your battery, terminals or the battery tray then using water and baking soda is a great solution.

Storing a Lawnmower Battery Over The Winter

Once you have finished using the your lawnmower for the season and it’s time to put it away for the winter, there are some things you want to do to make sure your lawnmower or lawn tractor is in the best possible condition for storage, this includes your battery. Firstly you’ll have wanted to thoroughly wash and dry your lawnmower / tractor removing any mud and grass. Next you will have to prepare for the winterisation and you may have your local dealer taking care of this for you, but if you’re doing it yourself then part of that process is preparing the battery and below we have some great tips to ensure you don’t have to purchase another battery for next season. When removing your battery from your lawnmower we would highly recommend carefully reading the owners manual, this will let you know the tools that you’ll need and the correct process they recommend as this may vary from model to model.

Frequently Asked Questions

There can be a few reasons why your battery may fail, but one of the most common is due to a lack of use. If you're not using your lawnmower or lawn tractor enough and it sits, perhaps in your garage for a period of time, the battery needs to be charged.

If the battery is not charged when the lawnmower is stored this can cause a chemical process called sulphation. When a battery is charged this chemical process cannot take place. However, when the battery’s voltage falls below 12.4 volts this process begins. The process causes sulphur crystals to form on the lead plates inside the battery, which in turn increases the battery’s electrical resistance. The longer this process is allowed to continue the worse the effect. Eventually the battery will become so electrically resistant, that you will be unable to charge the battery, let alone draw power from it.

If this process is caught early you may be able to salvage the battery using a battery charger with a pulse charge function. This will partially break down the sulphur crystals but the battery will never reach its full capacity again.

It is important to remember that if your battery fails due to sulphation this will not be covered under warranty. This kind of failure is classed as damage caused by the user through neglect.

Battery cables, the terminals on the end and the terminal connections to the battery, can all be susceptible to corrosion from the environment your lawnmower operates in. It is important to keep these free of dirt and corrosion but also to check the condition of the battery cable and terminals. If you find traces of corrosion on the cable and or terminals seek the advice of your local dealership, they can advise you if the cables or terminals need to be replaced.

Loose, dirty or corroded terminals can interrupt the power flow from the battery, causing it to be ineffective, leading to symptoms similar to a dead battery. Make sure the terminals are secure and connected correctly. Use a solution of water and baking soda to remove corrosion build-up.

By disconnecting the battery this will prevent excess discharge even when the engine is off, electronic equipment can continue to drain the battery, affecting the battery lifespan and it's ability to power the lawnmower or lawn tractor.

It is important to note that even with the battery disconnected, you will need to check the battery charge level and charge accordingly. A disconnected battery will discharge overtime naturally, however not at the same rate as if it were connected to your lawnmower or lawn tractor.

The exception to this is Lithium batteries, as they can be charged and disconnected from the machine and happily sit for twelve months before being used again, down to their chemical technology. If you were looking to use your Lithium battery for the first time in a few months we would always advise you charge your battery fully prior to use.

The simple answer is yes. If you start and stop your lawnmower engine frequently whilst typically mowing, then it would be good practice to make sure the battery is fully charged ready for the next time you wish to use it.

If you run your engine for long periods of time whilst mowing and also use your mower frequently then you will not need to charge your battery as frequently.

When preparing to store your lawnmower, always fully charge your battery prior to storage.

When you take your lawnmower out of storage for the first time (along with the usual checks you would undertake) you want to check and charge the battery fully, to make sure it is prime condition before heading to the lawns.

Manufacturers we stock