If you are thinking about buying a cordless mower, there might be one question that is of more importance to you than any other.
How long do electric lawn mower batteries last per charge?
After all you don’t want to have to keep stopping to charge the battery up midway through cutting your lawn.
There isn’t a one-size fits all answer, but there are a few important things you should pay attention to.
We explore them all in this article.
So without further ado, let’s get started.
How Long Do Electric Lawn Mower Batteries Last Per Charge?
Electric lawn mower batteries come in all different capacities, and runtime is also affected by things like how thick and wet the grass is. To get an idea of how long your mower battery will last, multiply the battery’s Ah capacity by the voltage. This will give you the total watt-hours for the battery, the higher the better.
What is Important to Look for in Lawn Mower Batteries?
As much as I’d love to tell you exactly how long your lawn mower battery will last per charge, it just isn’t possible.
There are simply so many variables.
That said, if you are buying a battery-powered lawn mower there are a few things to look out for when it comes to the battery.
Perhaps the thing people get most confused about is they think the higher the voltage of a battery the longer it will last.
But that isn’t true.
To know the duration of a battery you must know its capacity.
The capacity is denoted by Ah on the specification, so for instance:
- The EGO Power+ LM2101 has a 65v, 5.0Ah battery.
- The WORX WG779 has a 40v, 4.0Ah battery.
- The Snapper XD has two 82v, 2.0Ah batteries.
The Ah is effectively the amount of charge that is stored in the battery, the higher the number the more charge it holds.
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So I would always suggest the first thing you should look at is the Ah capacity of the battery.
But voltage does play a role. When you multiply the Ah number of a battery by the voltage of a battery you get watt-hours, this is the energy the battery can provide.
And it is watt-hours (WH) that in reality gives the best indication of how long you can expect the battery to last.
So let’s work that out for the three mowers above:
- EGO Power+ LM2101: 5 x 65 = 325WH
- WORX WG779: 4 x 40 = 160WH
- Snapper XD: 2 x 2 x 82 = 328WH
As you can see, your eye might initially be caught by the 82v figure of the Snapper XD, but the actual power the battery provides is almost identical to the 65v EGO Power+ LM2101.
So as a reminder, if you are deciding which cordless lawn mower to buy and considering battery capacity, do the following calculation:
Ah x Volts (v) = Watt-hours (WH)
In an ideal world, you want a lawn mower battery that has a high Ah number, a high V number and a motor that is energy efficient.
If you find a mower with these qualities you will get a good run time per charge (although as a disclaimer it will probably be more expensive!).
Hope that clears that up.
What Else Affects the Run Time of a Lawn Mower Battery?
Regardless of what size battery your mower has there are also several other factors that will affect how long it runs for.
The motors of most lawn mowers will draw a variable amount of current depending on their usage.
So if your grass is particularly long, thick and wet it will require more power to cut and will run down your battery quicker.
If you mow your grass regularly and have a nice flat lawn, then the battery will not be depleted anywhere near as much.
That is why it is difficult to say exactly how long a lawn mower battery will last per charge.
But still I know some of you reading this article will be looking for some direct, first-hand experience.
So I’ve pasted below some comments from various users on their cordless mowers and how long the batteries last:
“My self-propelled Ryobi 40v, 6Ah cuts my acre-plus lawn, weed whacks it and blows it clear and still has a quarter to half of it charge left.”
“My WORX 2 x 20v, 4Ah cuts three-quarters of an acre easily.”
“I have a Greenworks 40v with a 4Ah and 2Ah battery. It is not enough to get through my 4k lawn unless it was bone dry, and I move quickly”
“I have a self-propelled Kobalt, it runs about 30 to 45 minutes depending on how high the grass is.”
“I have an EGO Power Plus LM2120 with a 7.5Ah battery. I am able to mow my 2,000 sq ft lawn around two to three times on a single charge.”
“My experience with my EGO Mower, is that I’ve never drained more than 40% of the 7.5Ah battery after mowing my 7,000 sq. ft lot for more than an hour.”
“I have an EGO POWER+ Select Cut 56-Volt Brushless 21-in Self-propelled mower with 7.5Ah battery and it has been excellent. It rarely even uses one bar of battery life cutting my 2,000 sq. ft yard.”
This is just a selection of feedback, but what it shows is the importance of the Ah capacity of a battery in conjunction with the voltage.
It also shows what we have already established, run time does depend on the conditions.
Getting the Most Out of Your Mower Battery
There are no two ways about it, lawn mower batteries are expensive.
So if you want to get the most out of your battery, both in terms of runtime and overall longevity, you need to look after it.
Following a few simple steps will mean it lasts longer and you won’t be shelling out your hard-earned cash to replace it as quickly.
I always try to avoid letting my mower battery fully discharge, as this can damage it.
If I find that the battery is down to about 20% I will stop and charge it up again, rather than trying to complete the job.
I also charge the battery after use, even if it isn’t empty. The charger that comes with your mower should shut off when it reaches a full charge.
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Like humans, batteries do not like extreme temperatures.
You should not leave the batteries in direct sunlight, as warm temperatures will degrade them, even more so if they have a full charge.
Store them in a cool, dark place such as a basement or shaded garden shed, where heat and rain can’t reach them.
If you are using your mower on a hot day be extra cautious and go slow to avoid overloads. Don’t charge your battery immediately after use on a warm day as charging will raise the temperature of the battery further.
At the other extreme batteries can also be damaged if they are too cold.
When the temperature drops below freezing store the battery indoors, and never in an airtight container like a plastic bag.
If you are storing your battery away for the winter, then follow the tips above about cold weather.
Make sure it is somewhere clean and dry and not too cold.
Also make sure the battery is somewhere between 50% and 75% charged when being put away for long-term storage.
Check the battery level regularly when it is in storage if the battery is over a couple of years old.
So the infographic above shows why it is so difficult to estimate how long an electric lawn mower battery will last.
Firstly, because batteries come in different capacities, and secondly because external conditions such as the weather and the length of the grass, etc, also play an important role.
The best way to get an idea of the ability of your battery mower is to look at the voltage and Ah of it. Multiply the two of them together and you will get the watt hours, the higher the figure the better the run time of your battery will be.
In other words don’t just pay attention to the voltage as an 82v mower with a 2Ah battery will provide 164 watt-hours, whereas a 40v mower with a 5Ah battery will provide 200 watt-hours.
If you find a battery-powered mower with a high Ah number and a high voltage, then you have the best of both worlds.
Hope this all makes sense!